AS CPACS Flashcards

1
Q

CPAC 1: Limitations & procedure of measuring molar volume of a gas

A

Procedure:
- reaction ethanoic acid and CaCO3
- measure CO2 with gas syringe
- repeat for increasing masses of CaCO3
Limitations:
- Gas escapes before bung put on
- some CO2 will dissolve in the water

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2
Q

CPAC 2: Tips to make an accurate standard solution

A
  • Wash to make sure all solid is transferred
  • Invert to mix solution thoroughly
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3
Q

CPAC 3: Uses of pipette and burette in titrations

A
  • Pipette used to accurately measure volume
  • ## burette used to add small volumes of liquid
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4
Q

CPAC 4: Rate of hydrolysis of haloalkanes
- Why are test tubes left in the water bath
- Why is nitric acid added
- How to measure the rate of hydrolysis

A
  • Test tubes left in water bath to make sure they are all the same temperature
  • nitric acid to remove carbonates
  • time taken for X to disappear / time for ppte to appear
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5
Q

CPAC 5: Oxidation of ethanol
- Why is reflux equipment used
- Why is distillation equipment used

A
  • Fully oxidise the aldehyde
  • Stop further aldehyde oxidation
  • ABG stop bubbling of liquid & allow smooth boiling
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5
Q

CPAC 5: Oxidation of ethanol
- Uses of reflux equipment
- Use of distillation for aldehydes
- Use of anti-bumping granules

A
  • reflux equipment used to fully oxidise the aldehyde
  • distil to stop further aldehyde oxidation
  • ABG stop bubbling of liquid & allow smooth boiling
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6
Q

CPAC 6: Chlorination
- Reactants
- Why is anhydrous CaCl2 used
- Separating aqueous and organic layers
- Removing unreacted acid
- Drying agent for organic layer
- Reason for distillation

A
  • HCl & 2-methylpropan-2-ol
  • Ensure any unreacted alcohol is in the aqueous layer
  • separating funnel used to separate organic and aq layer by draining
  • NaHCO3 solution removes unreacted HCl
  • Na2SO4 used to remove water from organic layer
  • Distil to purify product
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7
Q

CPAC 8: Hess Law enthalpy change
- How to reduce uncertainty
- Why can enthalpy change not be measured directly
- Suggest reasons for differences in experimental and theoretical enthalpy values
- How to get a more accurate experimental value

A
  • larger mass used & greater resolution equipment
  • thermal energy needed to start reaction
  • Heat loss, incomplete combustion, non standard conditions, water evaporation
  • insulate to avoid heat loss and use a digital thermometer
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