OCR CHEMISTRY A PAPER H432 01 MARK SCHEME SET 1 EXAM SCRIPT 2026 FULL SOLUTIONS AND CORRECT ANSWERS GRADED A+

OCR CHEMISTRY A PAPER H432 01 MARK
SCHEME SET 1 EXAM SCRIPT 2026 FULL
SOLUTIONS AND CORRECT ANSWERS
GRADED A+

⩥ Test for ammonium ions. Answer: -add sodium hydroxide
-warm the mixture
-hover damp red litmus paper over it , if it turns blue the ions are present


⩥ Test for sulphate ionz (SO4 2-). Answer: - add dilute HCL
- then add BaCl2
- BaSO4 is made which is insoluble in water so a white precipitate will
be formed


⩥ Test for Halides (Cl-, Br-, I-). Answer: - add nitric acid
- add silver nitrate
- precipitates will be formed
- Cl (white) , Br (cream) , I (yellow)


⩥ Why add dilute acids when testing for ions ?. Answer: it will get rid of
any lurking anions that may create false positives

, ⩥ Endothermic energy profile diagram. Answer: products are higher
than reactants


⩥ Exothermic energy profile diagram. Answer: reactants are higher than
products


⩥ What are standard conditions?. Answer: 298K and 100kPa


⩥ Enthalpy change of reaction. Answer: the enthalpy change when the
reaction occurs in molar quantities shown in the chemical equation
under standard conditions


⩥ Enthalpy change of formation. Answer: the enthalpy change when 1
mole of compound is formed from it's elements in their standard states
under standard conditions


⩥ Enthalpy change of combustion. Answer: the enthalpy change when 1
mole of a substance is burned completely in oxygen under standard
conditions


⩥ Enthalpy change of neutralisation. Answer: the enthalpy change when
an acid and alkali react under standard conditions to form 1 mole of
water