Two rates experiment

Question 1

MG and HCL practical step 1-3

Answer 1

1) add a set volume of dilute HCL to a conical flask and carefully place on mass balance
2) Now add some MG ribbon to the acid and quickly plug flask with cotton wool
3) Start the stop watch and record the mass on the balance . Take readings of mass at regular intervals

Question 2

MG and HCL practical step 4 -6

Answer 2

4) Plot results on table and work out mass lost for each reading .Plot a graph , time = x axis, loss of mass = y axis
5) repeat with more concentrated acid solutions, variables like amount of mg ribbon and volume of acid = kept same = fair test
6) 3 graphs show that high conc of acid = faster rate of reaction

Question 3

Sodium thiosulfate and HCL practical steps 1-4

Answer 3

1- both chemicals are clear solutions, they react to form yellow precipitate of sulphur.
2 - Add set volume of dilute sodium thiosulfate to conical flask

3 - place flask on piece of paper with a black cross drawn on it, add some dilute HCL to flash and start stopwatch.
4 - Now watch black cross disappear through cloudy sulphur and time how long it takes to go.

Question 4

Sodium thiosulfate and HCL practical steps 5-6

Answer 4

• The reaction can be repeated with solutions of either reactants at diff conc. The depth of the liquid must be kept the same.
• The result shows the effect of increasing conc of HCL on rate of reaction, when added to an excess of sodium thiosulfate

Question 5

Sodium thiosulfate and HCL practical steps 7-8

Answer 5

• high concentration = quicker reaction, less time for mark to disspear
• This reaction does not give a set of graphs but you get a set of readings