2.1.3 Amount of substance

Question 1

Define (one) mole

Answer 1

Amount of substance that contains 6.02x1023 particles

Question 2

Avogadro constant

Answer 2

The number of particles per mole, 6.02x1023 mol-1

Question 3

Molar mass

Answer 3

Mass per mole of a substance (units= g mol-1)

Question 4

Molar gas volume

Answer 4

Gas volume per mole
(units= dm3 mol-1)

The volume occupied by one mole of any gas (24 dm³ or 24000 cm³ at room temperature and pressure).

Question 5

Empirical formula

Answer 5

Simplest whole number ratio of atoms of each element
present in a compound

Question 6

Molecular formula

Answer 6

Number and type of
atoms of each element in a molecule

Question 7

Anhydrous

Answer 7

Contains no water of crytsallisation

Question 8

Hydrated

Answer 8

The solid crystals contain water of crystallisation

Question 9

Water of crystallisation

Answer 9

Water that is chemically bonded into a crystal structure

Question 10

Recall calculation involving mass

Answer 10

n = m / Mr

Question 11

Recall calculation involving gas volume

Answer 11

Volume = n × molar volume

Question 12

Recall calculation involving solution volume and concentration

Answer 12

n = conc. x volume

Question 13

Recall Ideal gas equation

Answer 13

pV=nRT

p=pressure (Pa)
V=volume (m3)
n=No. of mol
R=gas constant
(8.31) (JK-1 mol-1)
T=temperature (K) (+273)

Question 14

Pressure at room temperature

Answer 14

1 atmosphere = 101 kPa
1kPa = 1,000 Pa
1 bar = 100,000 Pa

Question 15

Room temperature

Answer 15

20 degrees celsius = 293 K

Question 16

Standard temperature

Answer 16

25 degrees celsius = 298 K

Question 17

Recall equation for percentage yield

Answer 17

Yield (%) =
Yield / Maximum theoretical yield x100

Question 18

Atom economy

Answer 18

Tells us what percentage of the mass of the reactant atoms ends up in the desired product

Question 19

Recall equation for atom economy

Answer 19

Atom economy (%) =
Molecular mass of desired product / Sum of molecular masses of all reactants x100

(large numbers in chemical equation count for atom economy)

Question 20

Benefits for sustainability of chemical processes with a high atom economy

Answer 20

-reactions with high atom economy are more sustainable than those with low atom economy because less of the mass of reactants ends up in the waste products
-waste product of 1 reaction may be used by a chemical producer as starting material for a different reaction >increases overall sustainability
-reactions with large input of energy are less sustainable