paper 3

Question 1

calibration curve procedure

Answer 1

prepare standard solutions of compound under investigation
obtain gas chromatogram for each standard solution and measure area under curve
plot calibration curve (peak area against concentration)
compare area under curve for compound under investigation with calibration curve

Question 2

calculating enthalpy change of neutralisation

Answer 2

enthalpy change per mole of water formed

Question 3

high temperature favours:

Answer 3

endo

Question 4

% component gas chromatography

Answer 4

area of peak/ area of all peaks

Question 5

1st ie

Answer 5

increases along
decreases down

Question 6

what are fcv

Answer 6

vehicles that use hydrogen-rich fuels in fuel cell eg methanol and methane
by
methanol converted to hydrogen on board vehicle in reformer (methanol combined with water) h2 fed into fuel cell
or
vehicle uses methanol directly

Question 7

advantage to methanol vs h2 as fuel

Answer 7

methanol is liquid- easier to store and trasnport

Question 8

advantage of methanol fuel cell to petrerol

Answer 8

less co2 from methanol fuel cell vs petrol
methanol is renewable
conventional fossil fuel engines 20% efficient vs fuel cells are 40-60% efficient

Question 9

disadavntages of hydrogen fuel cells

Answer 9

h2 gas very difficult to transport
h2 difficult to store (liquid under pressure at very low temp or adsorb onto surface of solid material or absorbed within a solid material)
adsorbers and absorbers need to be replaced often and disposed of
fuel cells have limited lifespan
fuel cells use toxic chemicals in their production
no hydrogen infrasturcture

Question 10

how does a fuel cell work

Answer 10

fuel and oxygen flow into the fuel cell and a voltage is created via an electrochemical reaction
different to storage cells as fuel supplied to cell with electrolyte inside, storage cells have all components stored within the cell

Question 11

reactivity of halogen down group

Answer 11

decreases

Question 12

test for carbonate and hydrogen carbonate ions

Answer 12

add acid to gas e.g nitric acid
everfessence
bubble gas through limewater (solution of calcium hydroxide)
CO2 + Ca(OH)2 > CaCO3(s) + H2O
calcium carbonate- cloudy- formed
nitric acid best acid as we can then go to test for sulphate and hallide after

Question 13

test for sulphate ionic eq

Answer 13

Ba2+ + SO4 2- > BaSO4 (S)
WHITE PPT

Question 14

test for hallides ionic

Answer 14

Ag+ + X- > AgX