Calculation of reacting masses, gas volumes and mole concentrations

Question 1

Mass: n (mol) =

Answer 1

m (g) / Mr (gmol-1)

Question 2

Gas volume: n (mol) =

Answer 2

volume (dm3) / 24 molar gas vol

Question 3

Concentration: n (mol) =

Answer 3

conc. (moldm3) x vol (dm3)

* For mass concentration, multiply mol. concentration by Mr.

Question 4

Standard solution

Answer 4

• A solution of known concentration.

- Prepared by dissolving an exact mass of the solute in a solvent and making up the solution to an exact volume.

Question 5

Molar gas volume

Answer 5

• The volume per mole of gas molecules at a stated temperature and pressure.
• At RTP molar gas vol. is 24 dm3 mol-1

Question 6

Ideal gas equation

Answer 6

pV = nRT
p is Pa
V is volume in M3
n is moles
R is the ideal gas constant 8.31
T is temperature in K so +273

Question 7

Assumptions for the molecules making up an ideal gas

Answer 7

• Random motion
• Elastic collisions
• Negligible size
• No intermolecular forces

Question 8

Conversions

Answer 8

• cm3 to m3 = x10^-6

- dm3 to m3 = x10^-3

Question 9

Stoichiometry

Answer 9

• The ratio of the amount, in moles, of each substance, given by the balancing numbers in a balanced equation.