2.2 - Amount of substance

Question 1

What is avogadro’s constant

Value + Definiton

Answer 1

6.02 x 10^23 g mol-1
the number of particles equivalent to the relative atomic, molecular or formula mass of a substance

Question 2

moles =

Answer 2

Mass/ Molar Mass

Question 3

What is the molar gas volume occupied by one mole of any gas at RTP

Answer 3

24 DM3

Question 4

What is Molecular formula

Answer 4

the number and type of each atom in a molecule

Question 5

What is Empirical formula

Answer 5

the simplest whole number ratio of the elements present in one molecule of the compound

Question 6

What is water of crystallisation

Answer 6

when some compounds can form crystals which have water as part of their structure

Question 7

What is a compound which contains water of crystallization known as

Answer 7

A hydrated compound

Question 7

What is a compound which contains water of crystallization known as

Answer 7

A hydrated compound

Question 8

what is A compound which doesn’t contain water of crystallisation known as

Answer 8

an Anhydrous compound

Question 9

How can you convert from anhydrous to hydrated compounds

Answer 9

Heating a hydrated salt

Question 10

define concentration

Answer 10

the amount of solute dissolved in a solvent to make 1 dm3 of solution

Question 11

Concentration =

Answer 11

Moles/Volume

Question 12

What do equal volumes of gases contain

Answer 12

the same number of molecules

Question 13

Volume of gas (dm3) =

Answer 13

moles of gas * 24dm^3

Question 14

What 5 assumptions does the kinetic theory of gases state

Answer 14

• That gas molecules are moving very fast and randomly
• That molecules hardly have any volume
• That gas molecules do not attract or repel each other (no intermolecular forces)
• No kinetic energy is lost when the gas molecules collide with each other (elastic collisions)
• The temperature of the gas is related to the average kinetic energy of the molecules

Question 15

What is the kinetic theory of gases

Answer 15

Molecules in gases are constantly moving

Question 16

What are ideal gases

Answer 16

Gases that follow the kinetic theory of gases

Question 17

What are real gases

Answer 17

gases in reality which come close to ideal gases

Question 18

What 2 things does the volume of an ideal gas depend on

Answer 18

pressure
Temperature

Question 19

Volume is directly proportional to what

Answer 19

temperature when pressure is constant

Question 20

limitations of ideal gases

Answer 20

At low temperatures and high pressures real gases don’t obey kinetic theory

Question 21

What is the ideal gas equation

Answer 21

PV = nRT

Question 22

what are the units for the ideal gas equation

Answer 22

P = pressure (pascals, Pa)

V = volume (m3)

n = number of moles of gas (mol)

R = gas constant (8.31 J K-1 mol-1)

T = temperature (kelvin, K)

Question 23

What are the 3 reasons why not all reactants react to form products

Answer 23

Other reactions take place simultaneously
The reaction does not go to completion
Products are lost during separation and purification

Question 24

Percentage yield =

Answer 24

actual yield/theoretical yield

Question 25

atom economy =

Answer 25

molecular mass of desired product/sum of molecular masses of all reactants