5: Formulae, Equations and Amounts of Substance

Question 1

What are moles?

Answer 1

Units for measuring the amount of stuff

Question 2

Avagadro’s constant

Answer 2

6.02 * 10^23

Question 3

Equation for Mr

Answer 3

Mr = m / mol

Question 4

Empirical formula definition

Answer 4

The simplest ratio showing the different types of atom present in a substance

Question 5

Molecular formula definition

Answer 5

The actual numbers of each type of atom in a molecule of the substance

Question 6

Real gas law

Answer 6

PV = nRT

Question 7

Universal gas constant

Answer 7

8.314 J/(K + mol)

Question 8

Formula for concentration

Answer 8

C = mol / V

Question 9

Formula for moles of a gas

Answer 9

mol = V /24dm^3

Question 10

Formula for % error

Answer 10

%Error = (Apparatus uncertainty / Amount being measured) * 100

Question 11

How to reduce uncertainty

Answer 11

Increasing the amount being measured

Question 12

Equation for % yield

Answer 12

% Yield = (Mass of material produced / Theoretical maximum mass to be produced) * 100

Question 13

Equation for % Atom economy

Answer 13

% Atom economy = (Molar mass of useful product / Total molar mass of starting materials) * 100