practical

Question 1

purification of solid product by recrystallisation

Answer 1

• dissolve in MINIMUM amount of HOT solvent
• cool
• filter (reduced pressure= buchner flask, or fluted fiilter paper)
• leave to dry

Question 2

potential risks

Answer 2

-flammable reagents = keep away from flame
-toxic reagents = fume cupboard/ gloves

Question 3

ensuring all of something has reacted

Answer 3

-measure till fixed mass
-pass inert gas through to prevent further reaction
-using excess

Question 4

initial rate (clock reactions)

Answer 4

-measuring initial rate of reaction with different concentrations of one reagent
-initial rate proportional to 1/t
-time is measured when reaction has not progressed much as it is approximation

Question 5

continuous method

Answer 5

-measuring some change over time e.g gas evolved or colorimeter change
-measurements taken in increments
-usually if more than one reactant one is in large excess so reaction has order 0 wrt that reactant

Question 6

prep standard sol

Answer 6

Dissolve solid in (distilled) water (less than 250 cm3) in
beaker
Transfer (solution) to volumetric flask
Transfer washings (from beaker) to flask
Make up to mark/up to 250 cm3 with (distilled) water
Invert flask (several times to ensure mixing)

Question 7

procedure using pH probe

Answer 7

• wash with distilled water in between uses
  -calibrate with solutions of known pH
  -record readings