WTM 31-1-19

Question 1

what is a use of fractional distillation

Answer 1

• separate fractions of crude oil
• make alcoholic drinks
• separate the gases in the air (after being cooled)

Question 2

how does fractional distillation compare to simple distillation

Answer 2

fractional distillation can be used to separate mixtures into several parts or fractions based on BP

Question 3

state what the atomic number for each element tells you about each atom

Answer 3

number of protons

Question 4

state what the mass number tells you about each atom

Answer 4

number of protons and neutrons

Question 5

define what an isotope is

Answer 5

same number of protons but a different number of neutrons

Question 6

how do we test for hydrogen

Answer 6

lit splint will go squeaky pop

Question 7

what is produced during the electrolysis of water

Answer 7

hydrogen and oxygen

Question 8

calculate the Mr of sodium chloride and calcium chloride, show your working

Answer 8

Na = 23 Cl = 35.5
1 x23 =23
1 x35.5 = 35.5
35.5 + 23 = 58.5

Question 9

show how to calculate the empirical formula of lithium carbonate if a sample contains 2.8g of lithium, 2.4g of carbon and 9.6g of oxygen

Answer 9

Li = 7 C=12 O = 16
divide 2.8 by 7 = 0.4
divide 2.4 by 12 = 0.2
divide 9.6 by 16 = 0.6

identify the smallest answer = 0.2
divide all by the smallest 
0.4/0.2 = 2
0.2/0.2 = 1
0.6/0.2 = 3

so you have 2 lithium, 1 carbon and 3 oxygen
Li2CO3

Question 10

what is the formula triangle for mass, moles and mr/ar

Answer 10

mass = moles x mr/ar

Question 11

where do most metals originate

Answer 11

earth’s crust in their ore

Question 12

why is copper used for electrical wires

Answer 12

conducts electricity

Question 13

list advantages of recycling metals rather than extracting more from their ore

Answer 13

• preserve natural ores
• need to mine ores is reduced
• less pollution from mining
• less waste metal in landfill

Question 14

give 1 use for each fraction of crude oil

Answer 14

gases - domestic heating and cooking
petrol - fuel for cars
kerosene - fuel for aircraft
diesel oil - fuel for some cars and trains
fuel oil - fuel for large ships and in some power stations
bitumen - surface roads and roofs

Question 15

what happens to the boiling point of the fractions of crude oil as they get longer

Answer 15

increases