Topic 5 Calculations

Question 1

Reasons an experiment may not have 100% yield

Answer 1

• incomplete reactions
• side reactions
• impure reactants
• loss in transfer

Question 2

What’s an empirical formula?

Answer 2

The simplest whole number ratio of the number of atoms of each element in a compound

Question 3

What does anhydrous mean?

Answer 3

No water

Question 4

Mass =

Answer 4

Mr x moles

Question 5

How to find yield when there’s a limiting reagent?

Answer 5

Find reactant with lowest moles and multiply by product Mr

Question 6

What is the ideal gas equation?

Answer 6

pV = nRT

Question 7

What are units for pV=nRT

Answer 7

p = Pa
V = m3
n = moles
R = J/K/mol
T = Kelvins

Question 8

How to convert C to K?

Answer 8

+ 273

Question 9

What is 1 atm to Pa?

Answer 9

100,000Pa

Question 10

What is 1m3 in dm3 and cm3?

Answer 10

1m3=1000dm3=1,000,000cm3

Question 11

What colour is phenolphalein in acidic and alkali conditions?

Answer 11

Colourless in acidic
Pink in alkali

Question 12

What is a mole?

Answer 12

Unit of substance measurement.
One mole of a substance contains as many substance units as there are atoms in 12g of carbon-12

Question 13

What is a relative atomic mass?

Answer 13

weighted mean mass of all isotopes compared to 1/12 of mass of a C-12 atom

Question 14

what is a relative molecular mass?

Answer 14

sum of all relative atomic mass present in molecule

Question 15

what does Ar mean?

Answer 15

relative atomic mass

Question 16

what’s a molar mass?

Answer 16

mass per mole of a substance
g mol -1

Question 17

What must be included when asked to write half equations?

Answer 17

Electrons

Question 18

What is molar mass?

Answer 18

Volume occupied by one mole of gas at a specific temp

Question 19

What’s the unit for molar mass?

Answer 19

g mol-1