Chemistry - 0620 CIE

The Mole And The Avogadro Constant

Gbogbo ọrọ náà

How do chemists count something as small and as numerous as atoms? You cannot tip them onto a balance one at a time, yet reactions happen atom by atom. The answer is the mole, a counting unit so large that it lets us weigh out exact numbers of particles, and the Avogadro constant that pins down just how many a mole contains.

In this lesson you will learn what a mole is, use the link between mass, moles and molar mass, and work with the molar gas volume of 24 dm3 at room temperature and pressure. You will calculate reacting masses, gas volumes, concentrations, empirical and molecular formulae, percentage yield and percentage purity: the quantitative heart of chemistry.

Ebumnobi

  1. State that concentration can be measured in g / dm3 or mol / dm3.
  2. [Supplement] State that the mole, mol, is the unit of amount of substance and that one mole contains 6.02 × 1023 particles, e.g. atoms, ions, molecules; this number is the Avogadro constant.
  3. [Supplement] Use the relationship amount of substance (mol) = mass (g) / molar mass (g / mol) to calculate: (a) amount of substance (b) mass (c) molar mass (d) relative atomic mass or relative molecular / formula mass (e) number of particles, using the value of the Avogadro constant.
  4. [Supplement] Use the molar gas volume, taken as 24 dm3 at room temperature and pressure, r.t.p., in calculations involving gases.
  5. [Supplement] Calculate stoichiometric reacting masses, limiting reactants, volumes of gases at r.t.p., volumes of solutions and concentrations of solutions expressed in g / dm3 and mol / dm3, including conversion between cm3 and dm3.
  6. [Supplement] Use experimental data from a titration to calculate the moles of solute, or the concentration or volume of a solution.
  7. [Supplement] Calculate empirical formulae and molecular formulae, given appropriate data.
  8. [Supplement] Calculate percentage yield, percentage composition by mass and percentage purity, given appropriate data.

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Maapụ uche

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Mee omume kaadị ndị a na ngwa

Akwụkwọ Ọmụmụ

Quantitative chemistry is what turns a recipe into a science. The mole lets you predict exactly how much product a reaction will give, how much reactant you need, and how pure your sample is. Industry, medicine and research all depend on these calculations, and they are some of the most heavily marked questions in the whole course.

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Nnyocha Ọmụmụ

Ekele diri gi maka imecha ihe karịrị na The Mole And The Avogadro Constant. Ugbu a na ị na-enyochakwa isi echiche na echiche ndị dị mkpa, ọ bụ oge iji nwalee ihe ị ma. Ngwa a na-enye ụdị ajụjụ ọmụmụ dị iche iche emebere iji kwado nghọta gị wee nyere gị aka ịmata otú ị ghọtara ihe ndị a kụziri.

Ị ga-ahụ ngwakọta nke ụdị ajụjụ dị iche iche, gụnyere ajụjụ chọrọ ịhọrọ otu n’ime ọtụtụ azịza, ajụjụ chọrọ mkpirisi azịza, na ajụjụ ede ede. A na-arụpụta ajụjụ ọ bụla nke ọma iji nwalee akụkụ dị iche iche nke ihe ọmụma gị na nkà nke ịtụgharị uche.

Jiri akụkụ a nke nyocha ka ohere iji kụziere ihe ị matara banyere isiokwu ahụ ma chọpụta ebe ọ bụla ị nwere ike ịchọ ọmụmụ ihe ọzọ. Ekwela ka nsogbu ọ bụla ị na-eche ihu mee ka ị daa mba; kama, lee ha anya dị ka ohere maka ịzụlite onwe gị na imeziwanye.

  1. How many particles are there in one mole of a substance? A. 6.02 x 10^23 B. 6.02 x 10^-23 C. 1000 D. 24 Answer: A
  2. What is the molar gas volume at room temperature and pressure? A. 12 dm3 B. 22.4 dm3 C. 24 dm3 D. 100 dm3 Answer: C
  3. How many moles are in 40 g of calcium? (Ar Ca = 40) A. 0.5 mol B. 1 mol C. 2 mol D. 40 mol Answer: B
  4. A compound has 0.4 mol C and 0.8 mol H. Its empirical formula is: A. CH B. CH2 C. C2H D. CH4 Answer: B
  5. A reaction gives 9 g of product from a maximum possible 12 g. The percentage yield is: A. 25% B. 75% C. 133% D. 3% Answer: B

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