OCR A Level CHEMISTRY PAPER 1 exam
with solutions
Test for carbonates - correct answer ✔- add dilute HCL
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- it makes carbon dioxide
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test for carbon dioxide by bubbling it through lime water
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Test for ammonium ions - correct answer ✔-add sodium hydroxide
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-warm the mixture | | |
-hover damp red litmus paper over it , if it turns blue the ions are present
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Test for sulphate ionz (SO4 2-) - correct answer ✔- add dilute HCL
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- then add BaCl2
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- BaSO4 is made which is insoluble in water so a white precipitate will be
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|formed
Test for Halides (Cl-, Br-, I-) - correct answer ✔- add nitric acid
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- add silver nitrate
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- precipitates will be formed
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- Cl (white) , Br (cream) , I (yellow)
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Why add dilute acids when testing for ions ? - correct answer ✔it will get rid of
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any lurking anions that may create false positives
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, Endothermic energy profile diagram - correct answer ✔products are higher
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than reactants
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Exothermic energy profile diagram - correct answer ✔reactants are higher than
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products
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What are standard conditions? - correct answer ✔298K and 100kPa
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Enthalpy change of reaction - correct answer ✔the enthalpy change when the
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reaction occurs in molar quantities shown in the chemical equation under
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standard conditions
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Enthalpy change of formation - correct answer ✔the enthalpy change when 1
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mole of compound is formed from it's elements in their standard states under
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standard conditions
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Enthalpy change of combustion - correct answer ✔the enthalpy change when 1
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mole of a substance is burned completely in oxygen under standard conditions
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Enthalpy change of neutralisation - correct answer ✔the enthalpy change when
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an acid and alkali react under standard conditions to form 1 mole of water
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Bond dissociation enthalpy - correct answer ✔The enthalpy change required to
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break a covalent bond with all species in the gaseous state
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with solutions
Test for carbonates - correct answer ✔- add dilute HCL
| | | | | | | | |
- it makes carbon dioxide
| | | | |
test for carbon dioxide by bubbling it through lime water
| | | | | | | | |
Test for ammonium ions - correct 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-) - correct 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-) - correct 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 ? - correct answer ✔it will get rid of
| | | | | | | | | | | | | | | |
any lurking anions that may create false positives
| | | | | | | |
, Endothermic energy profile diagram - correct answer ✔products are higher
| | | | | | | | |
than reactants
| |
Exothermic energy profile diagram - correct answer ✔reactants are higher than
| | | | | | | | | |
products
|
What are standard conditions? - correct answer ✔298K and 100kPa
| | | | | | | | |
Enthalpy change of reaction - correct answer ✔the enthalpy change when the
| | | | | | | | | | |
reaction occurs in molar quantities shown in the chemical equation under
| | | | | | | | | | |
standard conditions
| |
Enthalpy change of formation - correct 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 - correct answer ✔the enthalpy change when 1
| | | | | | | | | | |
mole of a substance is burned completely in oxygen under standard conditions
| | | | | | | | | | | |
Enthalpy change of neutralisation - correct answer ✔the enthalpy change when
| | | | | | | | | |
an acid and alkali react under standard conditions to form 1 mole of water
| | | | | | | | | | | | | |
Bond dissociation enthalpy - correct answer ✔The enthalpy change required to
| | | | | | | | | |
break a covalent bond with all species in the gaseous state
| | | | | | | | | | |
