AS CPACS Flashcards
CPAC 1: Limitations & procedure of measuring molar volume of a gas
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
CPAC 2: Tips to make an accurate standard solution
- Wash to make sure all solid is transferred
- Invert to mix solution thoroughly
CPAC 3: Uses of pipette and burette in titrations
- Pipette used to accurately measure volume
- ## burette used to add small volumes of liquid
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
- 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
CPAC 5: Oxidation of ethanol
- Why is reflux equipment used
- Why is distillation equipment used
- Fully oxidise the aldehyde
- Stop further aldehyde oxidation
- ABG stop bubbling of liquid & allow smooth boiling
CPAC 5: Oxidation of ethanol
- Uses of reflux equipment
- Use of distillation for aldehydes
- Use of anti-bumping granules
- reflux equipment used to fully oxidise the aldehyde
- distil to stop further aldehyde oxidation
- ABG stop bubbling of liquid & allow smooth boiling
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
- 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
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
- 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