a) (i) Define the term Avogadro's number.
(ii) If 2.30 g of an oxide of nitrogen, x, contains 3.01 x 1022
molecules, calculate the molar mass of x.
(iii) Deduce the formula of x. N, =6.02 x 10", N =14.0, O = 16.0]
(b)(i) Describe briefly what happens when each of the following substances are added to water:
(I) CCI4
; (II) SiCI4
,
(ii) Explain briefly why the reactions in (a)(i), (b)(i), (I) and (b)(ii) (II) are different Study the diagram below and answer the questions that follow.
(c) Study the diagram below and answer the questions that follow.
(i) What is the set up used for?
a)
(i) Avogadro's number is the number of particles (atoms, molecules, ions, etc.) present in one mole of a substance. It is approximately equal to 6.02 × 1023 particles per mole.
(ii) First, we need to calculate the number of moles of x in the given sample:
Number of moles = Number of particles / Avogadro's number
Number of moles = 3.01 × 1022 / 6.02 × 1023
Number of moles = 0.05 mol
Molar mass of x = Mass of x / Number of moles
Molar mass of x = 2.30 g / 0.05 mol
Molar mass of x = 46 g/mol
(iii) The empirical formula of x can be determined by finding the ratio of the atoms present in it. Since the molar mass of x is 46 g/mol and it contains nitrogen and oxygen, we can assume that the formula is NxOy. The ratio of N to O can be determined using the atomic masses of N and O and the given molar mass:
Molar mass of NxOy = (N × 14.0) + (y × 16.0) = 46
N + y = 3.29
Since N and y must be integers, the closest possible ratio is N:O = 1:2. Therefore, the formula of x is N2O.
(b)
(i) When CCl4 is added to water, it does not dissolve as it is a nonpolar substance and water is a polar solvent. When SiCl4 is added to water, it reacts with water to form HCl and SiO2, which precipitates as a white solid.
(ii) The reactions in (a)(i), (b)(i), (I), and (b)(ii) are different because they involve different substances and chemical reactions with water. In (a)(i), an oxide of nitrogen is being analyzed for its molar mass and formula. In (b)(i), two substances that are insoluble or react with water are being added to it. In (I), Pb(NO3)2 is being added to NaCl solution to precipitate PbCl2. In (b)(ii), SiCl4 is reacting with water to form HCl and SiO2.
(c)
(i) The setup is a simple distillation apparatus. It is used to separate a mixture of liquids with different boiling points by heating the mixture and collecting the condensed vapors. The mixture is heated in a distillation flask, and the vapors travel up the fractionating column, which contains several trays or packing material. The vapor with the lower boiling point condenses on the trays or packing, and the vapor with the higher boiling point continues to the condenser, where it is cooled and collected as a liquid. This allows for the separation of the components of the mixture based on their boiling points.
a)
(i) Avogadro's number is the number of particles (atoms, molecules, ions, etc.) present in one mole of a substance. It is approximately equal to 6.02 × 1023 particles per mole.
(ii) First, we need to calculate the number of moles of x in the given sample:
Number of moles = Number of particles / Avogadro's number
Number of moles = 3.01 × 1022 / 6.02 × 1023
Number of moles = 0.05 mol
Molar mass of x = Mass of x / Number of moles
Molar mass of x = 2.30 g / 0.05 mol
Molar mass of x = 46 g/mol
(iii) The empirical formula of x can be determined by finding the ratio of the atoms present in it. Since the molar mass of x is 46 g/mol and it contains nitrogen and oxygen, we can assume that the formula is NxOy. The ratio of N to O can be determined using the atomic masses of N and O and the given molar mass:
Molar mass of NxOy = (N × 14.0) + (y × 16.0) = 46
N + y = 3.29
Since N and y must be integers, the closest possible ratio is N:O = 1:2. Therefore, the formula of x is N2O.
(b)
(i) When CCl4 is added to water, it does not dissolve as it is a nonpolar substance and water is a polar solvent. When SiCl4 is added to water, it reacts with water to form HCl and SiO2, which precipitates as a white solid.
(ii) The reactions in (a)(i), (b)(i), (I), and (b)(ii) are different because they involve different substances and chemical reactions with water. In (a)(i), an oxide of nitrogen is being analyzed for its molar mass and formula. In (b)(i), two substances that are insoluble or react with water are being added to it. In (I), Pb(NO3)2 is being added to NaCl solution to precipitate PbCl2. In (b)(ii), SiCl4 is reacting with water to form HCl and SiO2.
(c)
(i) The setup is a simple distillation apparatus. It is used to separate a mixture of liquids with different boiling points by heating the mixture and collecting the condensed vapors. The mixture is heated in a distillation flask, and the vapors travel up the fractionating column, which contains several trays or packing material. The vapor with the lower boiling point condenses on the trays or packing, and the vapor with the higher boiling point continues to the condenser, where it is cooled and collected as a liquid. This allows for the separation of the components of the mixture based on their boiling points.
