Topic 9 + 10 Kinetics + Equilibrium

Question 1

How to find molar volume of a gas practical technique

Answer 1

Use a gas syringe or use a measuring cylinder full of water

Question 2

Sources of error when finding molar volume of gas

Answer 2

Rate of reaction is fastest at beggining so gas is lost with no gas syringe attached
CO2 can dissolve in water

Question 3

How to prevent effects of fast initial RoR and CO2 dissolving in water for molar volume practical

Answer 3

Saturate solution by adding CO2 beforehand.
Use a smaller container and seal and then tip inside.

Question 4

What is a standard solution

Answer 4

a solution with a known concentration of a substance in it

Question 5

Method for preparing standard solution

Answer 5

1. Weigh by difference when adding acid salt
2. Add 50 cm3 water to solid and stir with a glass rod
3. Use a funnel to pour solution into a volumetric flask. Wash everything 3 times with distilled water
4. Avoid parralax error by keeping at eye level up to 250 cm3
5. invert 7 times.

Question 6

How to reduce error when preparing standard solution

Answer 6

Use something with a high Mr so % error is less
Use a pure sample
Use a non air sensitive sample

Question 7

What is a concordant result

Answer 7

Within 0.2 cm3

Question 8

What can we read a burette to

Answer 8

0.05 cm3

Question 9

Methyl orange change

Answer 9

Red acid, orange neutral, yellow alkali

Question 10

Phenolpylein change

Answer 10

Colorless acid, pink alkali

Question 11

Why might phenolphthalein turn colorless

Answer 11

Reacts with air

Question 12

Sources of error and mitigating when investigating rates of hydrolysis

Answer 12

Using a water bath to control temperature
Using lower temperature to produce a lower uncertainty

Question 13

What apparatus do we use to oxidise ethanol to ethanal

Answer 13

Distillation with addition

Question 14

What apparatus do we use to oxidise ethanol to ethanoic acid

Answer 14

Heating under reflux

Question 15

Why do we use anti bumping granules

Answer 15

To prevent the formation of large gas molecules that cause violent boiling

Question 16

What color change of what occurs when ethanol is oxidised

Answer 16

Pottasium dichromate goes from orange to green

Question 17

Technique for chlorination of tertiary alcohol

Answer 17

1. Add together with HCL in flask and swirl
2. Release bung every 20 seconds to release pressure
3. Add anhydrous CaCl2 and shake to produce 2 distinct layers
4. Organic layer it upper layer
5. Add NaHCO3 to remove unreacted HCl
6. Invert and release pressure
7. Seperating funnel to separate
8. Add drying agent, Na2SO4
9. Decant or filter liquid
10. Distill to purify

Question 18

Why can enthalpy change of decomposition sometimes not be measured directly

Answer 18

Cannot distinguish between heat we are adding and heat given off in reaction

Question 19

How to improve the polystyrene cup apparatus for calculating enthalpy change

Answer 19

Lid, stirring, insulating material

Question 20

Source of error when calculating enthalpy change

Answer 20

Using specific heat capacity of water when new solution is different