Two Rates Experiment

Question 1

Magnesium and HCl react to produce H2 Gas!

Answer 1

Start by adding a set volume of dilute hydrochloric acid to a conical flask and carefully place on a mass balance.

Now add some Magnesium ribbon to the acid and quickly plug the flask with cotton wood

Start the stopwatch and record the mass on the balance. Take readings of the mass at regular intervals.

Plot results in a table and work out mass lost for each reading. Now plot a graph with time on the x-axis and loss of mass on y-axis.

Repeat with more concentrated acid solutions. - only changing the acid’s concentration. Keep the volume of acid and volume of magnesium ribbon the same to make your experiment a fair test.

Graph shows that a higher concentration of acid fives a faster rate of reaction.

Question 2

Sodium Thiosulfate and HCl produce a Cloudy precipitate!

Answer 2

Both chemicals are clear solutions. They react together to form a yellow precipitate of sulfur.

Start by adding a set volume of dilute sodium thiosuflate to a conical flask

Place flask on piece of paper with black cross drawn on it. Add some dilute HCl to the flask and start the stopwatch.

Now watch the black cross disappear through the cloudy sulfur and time how long it takes to go.

Reaction can be repeated with solutions of either reactant at different concentrations

The results should show the effect of increasing the concentration of HCl on the rate of reaction, when added to an excess of sodium thiosulfate

The higher the concentration, the quicker the reaction and therefore the less time it takes for the mark to disappear.