JAMB UTME - Chemistry - 2024

When the subsidiary quantum numbers (l) equals 1, the shape of the orbital is 

Answer Details

The subsidiary quantum number, often referred to as the azimuthal quantum number or angular momentum quantum number, is denoted by l. This quantum number defines the shape of the atomic orbital. The value of l determines the type of orbital as follows:

• l = 0: This corresponds to an s orbital, which has a spherical shape.
• l = 1: This describes a p orbital, which has a dumb-bell shape.
• l = 2: This corresponds to a d orbital, which has a more complex shape, often described as a cloverleaf.
• l = 3: This describes an f orbital, which has an even more complex structure.

For l = 1, the atomic orbital is a p orbital, which is characterized by its dumb-bell shape. This means that the electron density is concentrated in two lobes on opposite sides of the nucleus, resembling a dumb-bell.

The principle which states that no two electrons in the same orbitals of an atom have same value for all four quantum numbers is the

Answer Details

The principle that states that no two electrons in the same orbitals of an atom can have the same value for all four quantum numbers is the Pauli Exclusion Principle.

To understand this principle, it's important to know a bit about the structure of an atom and what quantum numbers are:

Quantum Numbers:
1. **Principal Quantum Number (n):** This describes the energy level or shell of the electron.
2. **Angular Momentum Quantum Number (l):** This describes the subshell or shape of the orbital (s, p, d, f...).
3. **Magnetic Quantum Number (m_l):** This describes the specific orbital within a subshell where the electron is located.
4. **Spin Quantum Number (m_s):** This describes the spin direction of the electron, which can be either +1/2 or -1/2.

The Pauli Exclusion Principle asserts that each electron in an atom has a unique set of these four quantum numbers. While electrons can share the first three quantum numbers if they are in the same orbital (meaning they share the same energy level, the same subshell, and the same specific orbital within that subshell), they must have different Spin Quantum Numbers. This means that in any given orbital, one electron can have a spin of +1/2 and the other must have a spin of -1/2. This principle is fundamental in explaining the electronic structure of atoms and, consequently, the behavior and properties of elements.

An example of highly unsaturated hydrocarbon is

Answer Details

To determine a highly unsaturated hydrocarbon, we must first understand the concept of saturation in hydrocarbons. **Saturated hydrocarbons** are compounds that contain the maximum possible number of hydrogen atoms, single-bonded to carbon atoms, and they are alkanes. **Unsaturated hydrocarbons** have one or more double or triple bonds between carbon atoms, which reduces the number of hydrogen atoms that can be bonded.

Examining the given options:

• C₂H₂ - also known as ethyne (or acetylene), has one carbon-carbon triple bond. A triple bond means it is highly unsaturated because it reduces the number of hydrogen atoms per carbon.
• CH₄ - known as methane, is a saturated hydrocarbon with single bonds only.
• C₂H₄ - known as ethene (or ethylene), has one carbon-carbon double bond, making it unsaturated.
• C₄H₁₀ - known as butane or isobutane, is another saturated hydrocarbon with single bonds only.

Based on this analysis, **C₂H₂** (ethyne) is a highly unsaturated hydrocarbon due to the presence of a **triple bond**. The triple bond signifies a greater level of unsaturation compared to double bonds in hydrocarbons like ethene (C₂H₄).

Strong acids can be distinguished from weak acids by any of the following methods, EXCEPT

Answer Details

To distinguish between strong acids and weak acids, we can employ several methods based on their chemical properties:

Conductivity Measurement: Strong acids dissociate completely in water, releasing more ions. Because ion concentration is directly related to electrical conductivity, strong acids exhibit higher conductivity than weak acids, which only partially dissociate.

Litmus Paper: This method helps determine if a solution is acidic or basic but does not provide detailed information about the strength (strong or weak) of an acid. Both strong and weak acids turn blue litmus red. Therefore, **litmus paper cannot effectively distinguish between a strong and a weak acid.**

Measurement of pH: Strong acids have a lower pH because they fully dissociate to release more hydrogen ions (H+), whereas weak acids have a relatively higher pH as they do not dissociate completely. Thus, pH measurement can distinguish the extent of acidity.

Measurement of Heat of Reaction: The heat of reaction can give insights into the strength of an acid because it involves the degree of ionization and the energetics associated with it. A strong acid will exhibit a different calorimetric response compared to a weak acid.

In summary, **litmus paper is not suitable for distinguishing between a strong and a weak acid**, as it only indicates acidity but does not reveal the strength of the acid.

What is the vapour density of 560cm3 ${}^3$ of a gas that weighs 0.4g at s.t.p?

[Molar Volume of gas at s.t.p = 22.4 dm3 ${}^3$ ]

Answer Details

To find the vapour density of a gas, you can use the formula:

Vapour density = (Molar mass of gas) / 2

However, first, we need to determine the molar mass of the gas. One can find the molar mass using the given data:

We know that at standard temperature and pressure (s.t.p.), 1 mole of any gas occupies 22.4 dm³. We need to convert the volume from cm³ to dm³ because the molar volume is given in dm³:

560 cm³ = 0.560 dm³

Now, let's find the number of moles in 0.560 dm³:

The number of moles (n) = Volume of gas (dm³) / Molar volume at s.t.p. (dm³/mol)

n = 0.560 dm³ / 22.4 dm³/mol

n = 0.025 moles

Given that the mass of the gas is 0.4 grams, we can find the molar mass by using the relation:

Molar Mass = Mass / Number of Moles

Molar Mass = 0.4 g / 0.025 moles

Molar Mass = 16 g/mol

Now that we have the molar mass, we can find the vapour density:

Vapour density = Molar mass / 2

Vapour density = 16 g/mol / 2

Vapour density = 8.0

Hence, the vapour density of the gas is 8.0.

Esterification reaction is analogous to

Answer Details

The **esterification reaction** is analogous to a **condensation reaction**. In chemistry, a **condensation reaction** is a type of chemical reaction where two molecules or functional groups combine to form a larger molecule, with the simultaneous loss of a small molecule, usually water. **Esterification** specifically involves the reaction between an acid (often a carboxylic acid) and an alcohol, resulting in the formation of an **ester** and the release of a molecule of water.

To explain this further, in an esterification reaction:

• An **alcohol** provides one part of the ester, containing the oxygen and part of the carbon chain.
• A **carboxylic acid** provides the other part, which includes the carbon double-bonded to an oxygen atom (the carbonyl group).
• The reaction produces the **ester** and water (**H₂O**) as byproducts.

Conversely, the other types of reactions you've mentioned have different mechanisms:

• An **oxidation reaction** involves the losing of electrons by a molecule, atom, or ion.
• A **neutralization reaction** involves the reaction of an acid and a base to form salt and water.
• A **hydrolysis reaction** essentially does the reverse of esterification, breaking an ester down into its constituent acid and alcohol with the addition of water.

Therefore, given the nature of how molecules join and release water, it's clear that the **esterification reaction** is analogous to a **condensation reaction**.

Hydrochloric acid is regarded as a strong acid because it

Answer Details

Hydrochloric acid (HCl) is regarded as a strong acid because it ionizes completely in water. This means that when HCl is dissolved in water, it breaks down entirely into hydrogen ions (H⁺) and chloride ions (Cl^-). In a solution, there are no molecules of HCl left; only its ions are present.

This complete ionization results in a high concentration of hydrogen ions, which is a key characteristic of strong acids. Because there are more hydrogen ions available, hydrochloric acid can readily participate in chemical reactions, particularly those involving proton transfers, like neutralization reactions with bases.

In summary, the reason HCl is considered strong is due to its ability to consistently and completely ionize in an aqueous solution, not because of its physical state, source, or reactive nature with bases. Therefore, the property that defines it as a strong acid is that it ionizes completely.

At a given temperature and pressure, a gas X diffuses twice as fast as gas Y. It follows that

Answer Details

To solve the problem, we can use **Graham's law of effusion**. This law states that the rate of effusion (or diffusion) of a gas is inversely proportional to the square root of its molar mass. Mathematically, this is represented as:

Rate of diffusion of Gas X / Rate of diffusion of Gas Y = sqrt(Molar mass of Gas Y / Molar mass of Gas X)

According to the given information, gas X diffuses **twice as fast** as gas Y. This implies:

2 = sqrt(Molar mass of Gas Y / Molar mass of Gas X)

To eliminate the square root, square both sides of the equation:

(2)^2 = Molar mass of Gas Y / Molar mass of Gas X

This simplifies to:

4 = Molar mass of Gas Y / Molar mass of Gas X

Rearranging the equation, we find:

Molar mass of Gas Y = 4 * Molar mass of Gas X

This means that **Gas Y is four times as heavy as Gas X**. Therefore, the correct statement is:

• **Gas Y is four times as heavy as Gas X**

In a chemical reaction, surface area of reactants can affect

Answer Details

The surface area of reactants affects the rate of a reaction between limestone and hydrochloric acid because it increases the number of collisions between the particles of the reactants. For example, if you have a large marble chip of calcium carbonate and hydrochloric acid, the acid can't reach all the calcium carbonate in the middle of the chip. If you break the marble chip into smaller pieces, you'll have a larger surface area for the acid to react with, and the reaction will happen faster. 

What would be the order of the electrolytic cell in an industry intending the production of silver plated spoons?

Answer Details

In the process of silver plating a spoon using an electrolytic cell, the correct configuration involves the following:

Cathode: The object to be plated, which in this case is the spoon. In an electrolytic cell, the cathode is where the reduction reaction occurs, and it is the surface on which the metal ions are deposited.

Anode: A rod made of silver. The anode is where oxidation occurs, meaning the silver rod will dissolve into the solution in the form of silver ions. These ions then move towards the cathode to be deposited as a thin layer on the spoon.

Electrolyte: A solution that contains a soluble silver salt (such as silver nitrate, AgNO₃). The silver ions from this salt help in the process of transferring the silver from the anode to the cathode.

Thus, the proper order for silver plating a spoon in an electrolytic cell for industrial production is: "Cathode is the spoon; anode is a silver rod; electrolyte is a soluble silver salt."

127g of sodium chloride was dissolved in 1.0dm3 ${}^3$ of distilled water at 250 ${}^0$C . Determine the solubility in moldm−3 ${}^{-3}$ of sodium chloride at that temperature. [Na = 23, Cl = 35.5] 

Answer Details

To determine the solubility of sodium chloride (NaCl) in mol/dm³ at the given temperature, you need to first calculate the number of moles of NaCl dissolved.

Step 1: Calculate the molar mass of NaCl.

The molar mass of a compound is found by adding the atomic masses of its constituent elements:

- Sodium (Na) has an atomic mass of 23.

- Chlorine (Cl) has an atomic mass of 35.5.

Thus, the molar mass of NaCl = 23 + 35.5 = 58.5 g/mol.

Step 2: Calculate the number of moles of NaCl.

The formula to calculate moles is:

Number of moles = Mass (g) / Molar mass (g/mol)

Given mass of NaCl = 127 g,

Number of moles = 127 g / 58.5 g/mol ≈ 2.17 mol

Step 3: Calculate the solubility in mol/dm³.

Since the sodium chloride is dissolved in 1.0 dm³ of water, the solubility is the same as the number of moles, since the volume is already 1.0 dm³.

Therefore, the solubility of sodium chloride at that temperature is 2.17 mol/dm³.

Rounded to the options given, 2.17 mol/dm³ is approximately equal to 2.2 mol/dm³.

How much of 5g of radioactive element whose half life is 50days remains after 200days?

Answer Details

To determine how much of a radioactive element remains after a certain period, we use the concept of half-life. The half-life of a substance is the time it takes for half of the initial amount of a radioactive element to decay. In this example, the half-life is given as 50 days.

We want to know how much of a 5g sample remains after 200 days. First, calculate how many half-lives occur in 200 days:

Number of half-lives = Total time elapsed / Half-life
                      = 200 days / 50 days
                      = 4 half-lives

Next, we calculate the remaining amount after each half-life period:

• Initial amount: 5g
• After first half-life (50 days): 5g / 2 = 2.5g
• After second half-life (100 days): 2.5g / 2 = 1.25g
• After third half-life (150 days): 1.25g / 2 = 0.625g
• After fourth half-life (200 days): 0.625g / 2 = 0.3125g

After 200 days, 0.31g of the radioactive element remains.

Which of these is the most preferred separation technique for the isolation of solutes where the purity of the constituent is of utmost importance?

Answer Details

When the **purity of solutes** is of utmost importance, the most preferred separation technique is **recrystallization**. This method is widely used in chemistry for purifying solid compounds.

Here's a simple explanation of **recrystallization**:

1. **Dissolving the Impure Compound**: The impure solid is dissolved in a suitable hot solvent. The choice of solvent is crucial; it should dissolve the compound well at high temperatures but poorly at low temperatures.

2. **Cooling the Solution**: The solution is slowly cooled. As it cools, the solubility of the compound in the solvent decreases, causing the pure compound to form crystals and precipitate out of the solution.

3. **Collection and Drying of Crystals**: The pure crystals are collected through filtration and then allowed to dry, separating them from any remaining impurities that stay dissolved in the solvent.

The **advantage** of recrystallization is that it allows for the **removal of impurities** that are either more soluble than the desired compound at low temperatures or less soluble at high temperatures, resulting in a more purified product. Therefore, when achieving high purity is a priority, **recrystallization** is often the method of choice.

A radioactive element of mass 1g has half-life of 2 minutes, what fraction of the substance would have disintegrated after 10 minutes?

Answer Details

Originalmass2n
  =   Residual mass

Where n = number of activity =  exposuretimehalflife

Given: 

Original mass = 1g, exposure time = 10 minutes , half life = 2 minutes, Residual mass = ?

Substituting all the given parameters appropriately, we have

                     n = 102 $\frac{\mathrm{<br>}}{}$

                     n = 5

Originalmass2n $\frac{\mathrm{<br>}}{}$ =   Residual mass

125
5  =   Residual mass

132 $\frac{\mathrm{<br>}}{}$     =   Residual mass

Residual mass =  132
 or 0.03125g

In the conductance of aqueous CuSO4 ${}_4$ solution, the current carriers are the

Answer Details

In the conductance of aqueous CuSO₄ solution, the current carriers are the hydrated ions.

Here's why:

• CuSO₄ in Water: When copper sulfate (CuSO₄) is dissolved in water, it dissociates into copper ions (Cu²⁺) and sulfate ions (SO₄^2-).
• Role of Water: In an aqueous solution, these ions become surrounded by water molecules. This surrounding by water is known as "hydration."
• Conductivity: The movement of these hydrated copper ions and sulfate ions through the solution constitutes the current in the solution. They are the mobile charge carriers that allow electric current to flow.

The other options can be understood as follows:

• Mobile Electrons: These are the primary current carriers in metallic conductors, not in ionic solutions like CuSO₄.
• Metallic Ions: This term generally refers to ions in a metallic lattice. In an aqueous solution, the relevant ions are hydrated, not metallic.
• Hydrated Electrons: This is not a correct term for describing the charge carriers in an aqueous CuSO₄ solution.

The correct answer is therefore hydrated ions because they enable the conduction of electricity through the aqueous solution.

The percentage of carbon(IV) oxide in air is

Answer Details

The air we breathe is made up of a mixture of gases. The most abundant gases in the atmosphere are nitrogen and oxygen, but there are other gases present in smaller amounts, one of which is carbon dioxide, chemically known as carbon(IV) oxide.

Carbon dioxide makes up approximately 0.03% of the Earth's atmosphere by volume. This value can also be expressed in different terms, such as 300 parts per million (ppm). Even though it is a small percentage, carbon dioxide plays a significant role in maintaining the Earth's temperature through the greenhouse effect.

In summary, the percentage of carbon(IV) oxide in air is 0.03%.

Solubility curve is a plot of solubility against 

Answer Details

A solubility curve is a plot of solubility against temperature. Let me explain in a simple way:

Solubility refers to the amount of a substance (solute) that can dissolve in a given quantity of solvent to form a homogeneous solution at a specified condition. The most common factor that affects solubility is the temperature.

Here's why a solubility curve typically involves temperature:

• For most solid solutes, as the temperature increases, the solubility also increases. This means that more solute can dissolve in the solvent at higher temperatures.
• This behaviour is because higher temperature generally provides more energy to the solute and solvent molecules, allowing them to interact more effectively and dissolve.
• Temperature can have different effects on the solubility of gases in liquids, where an increase in temperature usually results in decreased solubility.

Therefore, plotting solubility against temperature in a solubility curve allows us to visualize and understand how solubility changes with variations in temperature.

An organic compound with general formula RCOR' is an

Answer Details

The general formula RCOR' represents a class of organic compounds known as ketones. In this formula, R and R' are alkyl groups, which are chains of carbon and hydrogen atoms. The CO in the middle is a carbonyl group, which consists of a carbon atom double-bonded to an oxygen atom. Therefore, with the presence of two alkyl groups on either side of the carbonyl group, the compound is categorized as a ketone, scientifically referred to as an alkanone.

Here is a simple breakdown of the terms:

• Alkanone: A term used to describe ketones, which have the general formula RCOR'.
• Alkanal: Represents aldehydes, which contain the functional group RCHO with at least one hydrogen attached to the carbon atom of the carbonyl group.
• Alkanoate: Typically refers to esters, which have the general form RCOOR'.
• Alkanoic acid: Refers to carboxylic acids, which are denoted by the functional group RCOOH.

Hence, by looking at the general formula RCOR', the organic compound in question is undoubtedly an alkanone.

The reaction between alkanoic acids and alkanols in the presence of an acid catalyst is known as

Answer Details

The reaction between alkanoic acids and alkanols in the presence of an acid catalyst is known as esterification.

An alkanoic acid, also known as a carboxylic acid, is a type of organic acid that contains a carboxyl group (-COOH). An alkanol, commonly referred to as an alcohol, contains a hydroxyl group (-OH).

When an alkanoic acid reacts with an alkanol in the presence of an acid catalyst (commonly sulfuric acid), they combine to form an ester and water. This particular reaction is termed esterification. The acid catalyst speeds up the reaction by donating protons, which helps in breaking and forming new bonds.

Here's a simplified view of the reaction:

1. Alkanoic Acid (R-COOH) + Alkanol (R'-OH) -> Ester (R-COOR') + Water (H2O)

The key characteristics of esterification are:

• Combination: It involves combining two different types of organic molecules, an acid, and an alcohol.
• Production of Water: Water is produced as a by-product of the reaction.
• Aromaticity: Esters often have a pleasant aroma, which is why many artificial flavors and fragrances are esters.

Therefore, in summary, the process described is esterification.

23892 ${}_{92}^{238}$U  + 10 ${}_0^1$n → 23992 ${}_{92}^{239}$U 

The process above produces 

Answer Details

The process described appears to depict a nuclear reaction involving a nuclear transmutation. Let's break down the process:

1. The starting element is initially denoted as "23892", which represents Uranium-238. In nuclear notation, "23892" indicates an atomic mass number of 238 and an atomic number of 92.

2. The next step so happens with the element "238"; however, the numbers remain: "92" indicates that the atomic number is unchanged, suggesting no change in the element. This often means a step in between of hypothetical notation.

3. Then there's the occurrence of adding a "U + 10", which again leaves the original atomic number "92".

4. In subsequent steps, it seems that the number "n" transitions to become "23992". The mass number has increased by one unit, turning the initial isotope into "23992", which represents Uranium-239.

The key point here is the transition from Uranium-238 to Uranium-239, which typically happens through the process of a neutron absorption in which a neutron is added, resulting in a change of the mass number. Such a process often leads to the creation of a radioactive isotope.

Therefore, the process described is indicative of producing a radioactive isotope, specifically Uranium-239.

Which of the following is an air pollutant?

Answer Details

An air pollutant is any substance in the air, introduced by natural or human activity, that causes harm or discomfort to living organisms, or damages the environment. Let's analyze the substances mentioned:

1. O₂ (Oxygen)
Oxygen is the gas we need to breathe. It's not considered an air pollutant because it is essential for human and animal life, as well as many natural processes.

2. CO (Carbon Monoxide)
Carbon Monoxide is a colorless, odorless gas that is produced by burning fuel (like in cars and factories). This gas can be very dangerous if there is a lot of it, as it can prevent oxygen from entering the bloodstream. Because of its harmful effects, it is considered an air pollutant.

3. H₂ (Hydrogen)
Hydrogen, while a flammable gas, is generally not harmful to the air or to organisms when it is released into the environment. Therefore, it is not considered an air pollutant.

4. O₃ (Ozone)
Ozone is a bit tricky because it is both good and bad. Higher up in the atmosphere, it forms a layer that protects us from the sun’s UV radiation. However, at ground level, it is a harmful air pollutant. Ground-level ozone can cause health problems such as respiratory difficulties, so in this context, it is considered an air pollutant.

In conclusion, the substances that are considered air pollutants in this context are Carbon Monoxide (CO) and ground-level Ozone (O₃).

The number of geometrical isomers of butene are 

Answer Details

To understand the geometrical isomers of butene, we need to explore its structure. Butene has four carbon atoms, and there are various structural forms that butene can take. These structural forms include linear or branched chains, with a double bond present between carbon atoms.

Geometric isomerism is a type of stereoisomerism. It occurs due to restricted rotation around the double bond, leading to different spatial arrangements of groups attached to the carbons forming the double bond. The geometric isomerism primarily occurs in alkenes like butene where the positions of substituents can vary.

Let's consider the different types of butene, focusing on the possibility of geometrical isomerism:

• 1-butene: This is a straight-chain isomer with the double bond starting at the first carbon. It doesn't show geometrical isomerism because the double bond is at the end of the chain, so there are no different spatial arrangements of groups possible.
• 2-butene: Here the double bond is between the second and third carbon. In this case, geometrical isomerism is possible because different groups (or atoms) attached to the carbon atoms can have different spatial arrangements. Specifically:
  • cis-2-butene: Both methyl groups (CH₃) are on the same side of the double bond.
  • trans-2-butene: The methyl groups are on opposite sides of the double bond.
• Isobutene (or 2-methylpropene): This is a branched isomer, and it does not have geometric isomers because the substituents around the double bond do not allow for different spatial configurations on either side of the double bond.

In conclusion, for butene, only 2-butene has geometrical isomers (cis and trans). Therefore, the number of geometric isomers is 2.

An example of a substance that does not change directly from solid to gas when heated is

Answer Details

When discussing the process of substances changing states, some substances can transition directly from a solid to a gas without passing through a liquid state. This process is called sublimation. However, not all substances exhibit this behavior. Let's examine the substances provided:

• Ammonium chloride (NH₄Cl): This substance can sublimate, meaning it can go directly from a solid state to a gaseous state when heated.
• Iodine (I₂): Iodine is known for sublimating as well. When iodine crystals are heated, they turn directly into a violet gas without becoming a liquid.
• Calcium carbonate (CaCO₃): This substance does not sublimate. Instead, when heated, it decomposes, releasing carbon dioxide gas and leaving calcium oxide as a residue. Therefore, it does not directly transition from a solid to a gas.
• Sulfur (S₈): This substance melts into a liquid before it evaporates, so it doesn't sublimate.

In conclusion, calcium carbonate (CaCO₃) is the substance that does not change directly from a solid to a gas when heated, as it undergoes a decomposition process instead.

In the extraction of Aluminium, the silica impurity is removed by 

Answer Details

Aluminum is extracted from bauxite by electrolysis. The extraction proceeds in two stages;

1. Purification of the Bauxite: The impure bauxite is heated with sodium hydroxide solution to form soluble sodium tetrahydroxy aluminate (iii). The impurities in the ore which are iron (iii) oxide and trioxosilicate (iv) compounds are not soluble in the alkali. They are therefore filtered off as a sludge. 

Aluminum hydroxide crystals is then added to filtrate, NaAl(OH)4 ${}_4$ solution to induce the precipitation of Aluminum hydroxide.

2. The electrolysis of the pure alumina

The quantity of electricity required to deposit 180g of Ag from a molten silver trioxonitrate(V) is

[Ag = 108]

Answer Details

To determine the quantity of electricity required to deposit 180g of Ag (silver) from molten silver trioxonitrate(V), we need to understand the concept of electrolysis. During electrolysis, a metal can be deposited according to Faraday's laws of electrolysis.

The equivalent weight of a substance is calculated by dividing the atomic mass by the valency. For silver (Ag), the atomic mass is given as 108 and the valency of silver in AgNO₃ is 1. This makes the equivalent weight of Ag 108 g/equivalent.

According to Faraday's first law of electrolysis:

Mass of substance deposited = (Equivalent weight × Quantity of electricity (in coulombs) ) / Faraday's constant (96500 C/mol)

Let's calculate the number of equivalents of silver deposited:

Number of equivalents of Ag = Mass of Ag / Equivalent weight = 180 g / 108 g/equivalent = 5/3 equivalents

The quantity of electricity required to deposit 1 equivalent of a substance is 1 Faraday (F) = 96500 C.

Therefore, the total quantity of electricity required:

Quantity of electricity = Number of equivalents × Faraday's constant

Quantity of electricity = (5/3 equivalents) × 1 F = 5/3 F = 1.67 F

Therefore, 1.67 Faraday is required to deposit 180g of Ag from a molten silver trioxonitrate(V).

The percentage of hydrogen in the sixth member of the class of the aliphatic alkanes is  [H =1, C =12 ]

Answer Details

To determine the percentage of hydrogen in the sixth member of aliphatic alkanes, we first need to understand the general formula for alkanes. Aliphatic alkanes are a class of hydrocarbons with the general formula C_nH_2n+2, where 'n' is the number of carbon atoms.

The sixth member of this series will have n = 6. Therefore, the molecular formula for the sixth member is C₆H₁₄.

To find the percentage of hydrogen, we first calculate the molar mass of C₆H₁₄:

• Molar mass of 1 carbon atom = 12
• Molar mass of 6 carbon atoms = 6 × 12 = 72
• Molar mass of 1 hydrogen atom = 1
• Molar mass of 14 hydrogen atoms = 14 × 1 = 14

Total molar mass of C₆H₁₄ = 72 + 14 = 86

Next, we calculate the percentage of hydrogen:

Percentage of hydrogen = (Molar mass of hydrogen atoms / Total molar mass) × 100

Percentage of hydrogen = (14 / 86) × 100 = 16.28%

Therefore, the percentage of hydrogen in the sixth member of the aliphatic alkanes is 16.28%.

The molecular formular of a hydrocarbon with an empirical formula of CH3 ${}_3$  and a molar mass of 30 is 

Answer Details

To find the molecular formula of a hydrocarbon given its empirical formula and molar mass, you need to compare the empirical formula mass with the given molar mass.

The empirical formula given is CH₃. The molar mass of the empirical formula is calculated as follows:

• Carbon (C): 1 atom × 12 g/mol = 12 g/mol
• Hydrogen (H): 3 atoms × 1 g/mol = 3 g/mol

Total empirical formula mass = 12 + 3 = 15 g/mol

The provided molar mass of the compound is 30 g/mol. To determine how many empirical units are in the molecular formula, divide the molecular mass (given) by the empirical formula mass:

Number of empirical units = 30 g/mol / 15 g/mol = 2

Therefore, the molecular formula is twice the empirical formula:

Empirical formula: CH₃

Molecular formula: (CH₃)₂ = C₂H₆

The correct molecular formula is C₂H₆.

Scandium is not regarded as a transition metal because its ion has 

Answer Details

Scandium is not regarded as a transition metal because its ion has no electron in the d-orbital.

To understand this, let's first define a transition metal. A transition metal is defined as an element that has an incomplete d-subshell in either its elemental form or in any of its common oxidation states.

When Scandium (Sc) loses electrons to form its most common ion (Sc³⁺), it loses three electrons. These electrons are removed from the 4s and 3d orbitals. The electron configuration for Scandium is [Ar] 3d¹ 4s². Upon losing three electrons to form Sc³⁺, the resulting electron configuration is [Ar], which means there are:

• No electrons in the 3d sublevel
• No electrons in the 4s sublevel

As a result, there are no electrons in the d-orbital of the Scandium ion, which does not meet the criteria for a transition metal.

The highest isotope of hydrogen is

Answer Details

Hydrogen has three naturally occurring isotopes, and each of them contains the same number of protons but different numbers of neutrons. Let's briefly differentiate them:

• Protium: This is the most common isotope of hydrogen, which has one proton and no neutrons. It's simply referred to as hydrogen.
• Deuterium: This isotope of hydrogen has one proton and one neutron. It is heavier than protium because of the additional neutron.
• Tritium: This is the heaviest naturally occurring isotope of hydrogen, consisting of one proton and two neutrons.

The highest isotope of hydrogen is tritium because it has the most neutrons and, therefore, the greatest atomic mass compared to the other isotopes. It is also noteworthy that tritium is radioactive, while the other hydrogen isotopes are stable.

Determine the half-life of a first order reaction with constant 4.5 x 10−3 ${}^{-3}$ sec−1 ${}^{-1}$.

Answer Details

To determine the half-life of a first-order reaction, you can use the formula:

Half-life (\(t_{1/2}\)) = \(\frac{0.693}{k}\)

where \(k\) is the rate constant of the reaction. For the given problem, the rate constant (\(k\)) is 4.5 x 10^-3 s^-1.

Substituting the value of \(k\) into the formula, we have:

\(t_{1/2} = \frac{0.693}{4.5 \times 10^{-3}}\)

Perform the division:

\(t_{1/2} = \frac{0.693}{4.5 \times 10^{-3}} \approx 154\) s

Therefore, the half-life of the reaction is 154 seconds.

The law which states that a pure chemical compound, no matter how it is made, will be made up of the same elements contained in the same proportion by mass is

Answer Details

The law that states a pure chemical compound, no matter how it is made, will be made up of the same elements contained in the same proportion by mass is the law of definite proportion.

To explain this simply, let's consider water as an example. Water is made up of hydrogen and oxygen. According to the law of definite proportion, a sample of pure water taken from anywhere in the world will always contain the same ratio of hydrogen to oxygen by mass. Specifically, water will always have approximately 88.8% oxygen and 11.2% hydrogen by mass.

This is because a chemical compound has a fixed composition, regardless of the process used to create it or the source from which it is derived. The law of definite proportion, also known as the law of constant composition, is fundamental in chemistry because it supports the idea that chemical compounds are composed of elements in specific and fixed ratios. This does not change regardless of how the compound is prepared or where it is found.

Boyle's law can be expressed mathematically as

Answer Details

Boyle's Law describes the relationship between the volume and pressure of a given amount of gas held at a constant temperature. It states that the pressure of a gas is inversely proportional to its volume. In simpler terms, if you decrease the volume of a gas, its pressure increases, provided the temperature remains constant, and vice versa.

The mathematical expression of Boyle's Law is PV = K, where:

• P represents the pressure of the gas.
• V represents the volume of the gas.
• K is a constant value when the temperature and the amount of gas are kept constant.

This relationship implies that if you multiply the pressure by the volume, the result will always be the same constant as long as no other variables are changed. This is the classic formulation of Boyle's Law, illustrating the inverse relationship between pressure and volume for a gas at constant temperature.

The term that is not associated with petroleum industry is ?

Answer Details

Cracking, saponification and polymerization are all terminologies associated with the petroleum industry but fermentation is associated with the brewery industry.

Cracking is a chemical process that breaks down heavy hydrocarbon molecules into lighter, more useful ones.

Saponification is a chemical reaction that converts fats and oils into soap. It's not directly involved in petroleum, but it can be used to analyze petroleum products.

Polymerization is a process in the petroleum industry that converts light olefin gases into higher molecular weight hydrocarbons.

Fermentation is the process in which a substance breaks down into a simpler substance. Microorganisms like yeast and bacteria usually play a role in the fermentation process, creating beer, wine, bread,yogurt and other foods.

The scientist that performed the experiment on discharged tubes that led to the discovery of the cathode rays as a sub-atomic particle is 

Answer Details

The **scientist who performed the experiment on discharge tubes that led to the discovery of cathode rays as a sub-atomic particle** is J.J. Thomson.

In the late 19th century, J.J. Thomson conducted experiments using a cathode ray tube. This device involved an evacuated glass tube with electrodes at each end, through which an electric current was passed. **When a high voltage was applied, Thomson observed a stream of particles traveling from the negative electrode (cathode) to the positive electrode (anode).** These streams of particles were what he called "cathode rays."

Through his experiments, J.J. Thomson discovered that these cathode rays were composed of negatively charged particles. **He concluded that these particles were much smaller than atoms, and named them "electrons," which are now known to be sub-atomic particles.** His work was fundamental in advancing the atomic model and in understanding the structure of the atom.

Thomson's discovery was pivotal because it provided the first evidence that atoms are not indivisible, but rather consist of smaller subatomic particles. This **challenged the then-prevailing notion of atoms as indivisible units**, thus marking the birth of modern particle physics.

If 11.0g of a gas occupies 5.6 dm3 ${}^3$ at s.t.p., calculate its vapour density (1 mole of a gas occupies 22.4 dm3 ${}^3$).

Answer Details

The problem requires calculating the **vapor density** of the gas. Vapor density is defined as the mass of a certain volume of a gas compared to the mass of an equal volume of hydrogen, where the hydrogen standard is 2 g/mol (as the molecular weight of hydrogen gas, H₂, is 2).

Here's a step-by-step explanation:

1. Molar Volume: At standard temperature and pressure (s.t.p.), 1 mole of any gas occupies a volume of 22.4 dm³.
2. Volume of Gas Provided: The given gas occupies a volume of 5.6 dm³.
3. Find Moles of Gas: Using the proportion of the molar volume:
   • Moles of Gas = Volume of Gas Provided / Molar Volume
   • Moles of Gas = 5.6 dm³ / 22.4 dm³/mole = 0.25 moles
4. Calculate Molecular Weight: Molecular weight (M) can be calculated using the relation:
   • M = Mass of Gas / Moles of Gas
   • M = 11.0 g / 0.25 moles = 44 g/mol
5. Vapor Density: Vapor density is half of the molecular weight of the gas.
   • Vapor Density = M / 2
   • Vapor Density = 44 g/mol / 2 = **22**

The calculated vapor density of the gas is 22.

An organic compound contains 53.1% Carbon, 6.2% Hydrogen, 12.4% Nitrogen, and 28.3% Oxygen by mass. What is the molecular formula of the compound if its vapour density is 56.5?   [ C =12, H = 1, N = 14, O = 16]. 

Answer Details

To find the molecular formula of the compound, follow these steps:

1. Determine the Empirical Formula:

Start by assuming you have 100 grams of the compound. This means you have:

• 53.1 grams of Carbon
• 6.2 grams of Hydrogen
• 12.4 grams of Nitrogen
• 28.3 grams of Oxygen

Now, convert these masses to moles using their atomic masses (C = 12, H = 1, N = 14, O = 16):

• Moles of Carbon = 53.1 g / 12 g/mol = 4.425 moles
• Moles of Hydrogen = 6.2 g / 1 g/mol = 6.2 moles
• Moles of Nitrogen = 12.4 g / 14 g/mol = 0.886 moles
• Moles of Oxygen = 28.3 g / 16 g/mol = 1.769 moles

Next, divide each by the smallest number of moles to get the simplest ratio:

• Carbon: 4.425 / 0.886 ≈ 5
• Hydrogen: 6.2 / 0.886 ≈ 7
• Nitrogen: 0.886 / 0.886 = 1
• Oxygen: 1.769 / 0.886 ≈ 2

This gives us the empirical formula: C₅H₇NO₂.

2. Determine the Molecular Formula:

The molecular formula is a multiple of the empirical formula. To determine this multiple, we need to find the empirical formula mass and compare it with the molar mass derived from the given vapor density.

Calculate the empirical formula mass:

• 5(C) + 7(H) + 1(N) + 2(O) = 5(12) + 7(1) + 1(14) + 2(16) = 101 g/mol

The molar mass can be calculated from the vapor density:

• Molar Mass = Vapor Density × 2 = 56.5 × 2 = 113 g/mol

Now, find the ratio of the molar mass to the empirical formula mass:

• Ratio = 113 / 101 ≈ 1.12

This ratio is approximately 1, indicating the molecular formula is the same as the empirical formula. Since empirical formulas typically should perfectly match the atomic proportions we derive from experiments, our calculations regarding the assumptions on the vapour and empirical formula mass remains our best match.

Therefore, the molecular formula is C₅H₇NO₂.

When a specie undergoes oxidation, its

Answer Details

When a species undergoes oxidation, it experiences an increase in its oxidation number. Oxidation is a chemical process where a species loses electrons. In terms of oxidation number, electrons have a negative charge, so losing them results in an increase in charge. Thus, the oxidation number of the species becomes more positive or less negative.

To help understand, consider sodium (Na) reacting with chlorine (Cl₂) to form sodium chloride (NaCl):

• Initially, the oxidation number of Na is 0 (it's in a pure element form).
• In NaCl, sodium now has an oxidation number of +1 (because it loses an electron).

This change clearly shows that when sodium is oxidized, its oxidation number increases.

Therefore, the correct explanation is: a species undergoing oxidation will have its oxidation number increase.

The number of molecules of helium gas contained in 11.5g of the gas is

Answer Details

To find the number of molecules of helium gas in a given mass, we can use Avogadro's number and the molar mass of helium.

Step 1: Determine the molar mass of helium.

Helium is a noble gas with an atomic mass of approximately 4 grams per mole (g/mol).

Step 2: Calculate the number of moles in 11.5 grams of helium.

The formula to find the number of moles is:

Number of moles = Mass (g) / Molar Mass (g/mol)

So for helium:

Number of moles = 11.5 g / 4 g/mol = 2.875 moles

Step 3: Use Avogadro's number to find the number of molecules.

Avogadro's number is 6.022 x 10²³ molecules per mole.

The formula to find the number of molecules is:

Number of molecules = Number of moles x Avogadro's Number

Number of molecules = 2.875 moles x 6.022 x 10²³ molecules/mole

Number of molecules ≈ 1.73 x 10²⁴ molecules

Therefore, the number of molecules of helium gas in 11.5g of helium is approximately 1.73 x 10²⁴.

How many isomers has the organic compound represented by the formula C3 ${}_3$H8 ${}_8$O ?

Answer Details

The molecular formula C₃H₈O represents organic compounds that contain 3 carbon atoms, 8 hydrogen atoms, and 1 oxygen atom. Let's elucidate the possible isomers, which are molecules with the same molecular formula but different structural arrangements.

1. Alcohols: One class of compounds that can form isomers for this formula are alcohols, which include a functional group -OH.

a. Propan-1-ol: This is a straight-chain alcohol where the -OH group is on the first carbon. The structure is as follows:

CH₃-CH₂-CH₂-OH

b. Propan-2-ol: This is another alcohol where the -OH group is on the second carbon, giving it a different structure and properties:

CH₃-CH(OH)-CH₃

2. Ethers: This is another class of possible isomers, where the oxygen atom is bonded to two alkyl groups.

c. Methoxyethane: Also known as ethyl methyl ether, it has a structure where the oxygen is in a bridge position between a methyl group and an ethyl group:

CH₃-O-CH₂-CH₃

These are the possible structural isomers for this molecular formula. Therefore, the compound C₃H₈O has three isomers overall:

• Propan-1-ol
• Propan-2-ol
• Methoxyethane

Thus, the answer is three distinct isomers.

The empirical formula of an organic liquid hydrocarbon is XY. If the relative molar masses of X and Y are 72 and 6 respectively, it's vapour density is likely to be

Answer Details

To determine the vapor density of the organic liquid hydrocarbon with the empirical formula XY, we first need to determine the **molecular formula** of the compound, which represents the actual number of atoms of each element in a molecule.

The **relative molar masses** of X and Y are given as 72 and 6, respectively. To find the molar mass of XY, we can add these values together:

Molar mass of XY = Molar mass of X + Molar mass of Y = 72 + 6 = 78 g/mol

Vapor density is defined as half of the molar mass of the compound, since vapor density is often compared to hydrogen, where hydrogen is taken as the standard with a molar mass of 2 g/mol. Therefore, vapor density can be calculated using the formula:

Vapor Density = (Molar Mass of the Compound) / 2

Substituting the molar mass of XY:

Vapor Density of XY = 78 / 2 = 39

Therefore, the vapor density of the hydrocarbon with the empirical formula XY is **39**.