OCR A A Level CHEMISTRY PAPER 1
EXAM QUESTIONS & ANSWERS
Test for carbonates - ANSWERS- add dilute HCL
- it makes carbon dioxide
test for carbon dioxide by bubbling it through lime water
Test for ammonium ions - ANSWERS-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-) - ANSWERS- 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-) - ANSWERS- add nitric acid
- add silver nitrate
- precipitates will be formed
- Cl (white) , Br (cream) , I (yellow)
Why add dilute acids when testing for ions ? - ANSWERSit will get rid of any lurking anions that
may create false positives
Endothermic energy profile diagram - ANSWERSproducts are higher than reactants
EXAM QUESTIONS & ANSWERS
Test for carbonates - ANSWERS- add dilute HCL
- it makes carbon dioxide
test for carbon dioxide by bubbling it through lime water
Test for ammonium ions - ANSWERS-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-) - ANSWERS- 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-) - ANSWERS- add nitric acid
- add silver nitrate
- precipitates will be formed
- Cl (white) , Br (cream) , I (yellow)
Why add dilute acids when testing for ions ? - ANSWERSit will get rid of any lurking anions that
may create false positives
Endothermic energy profile diagram - ANSWERSproducts are higher than reactants
