How the Concentration of Sodium Thiosulphate Affects the Rate of Reaction with Hydrochloric Acid

How the Concentration of Sodium Thiosulphate Affects the Rate of Reaction with Hydrochloric Acid

Plan

We will set up a conical flask on top a cross. We will vary the

concentration of Sodium Thiosulphate by putting different amounts of

Sodium Thiosulphate and water bye keeping the same total volume of

50cm³. We will then add 5cm³ of hydrochloric acid. We will time how

long it takes for the cross to completely disappear from site after

the reaction has completely finished.

Constants

Variables

Temperature

Concentration of Sodium Thiosulphate

Total amount of Sodium Thiosulphate + Water

Size of conical flask

Amount of hydrochloric acid

Hydrochloric acid concentration

Same person seeing when the cross disappears completely

Experiment

Prediction

If the concentration of sodium Thiosulphate is change I predict that

the rate of reaction will change. The higher concentration of Sodium

Thiosulphate per cm³ the quicker the reaction will take place. This is

because the more Sodium Thiosulphate particles there are, the more

chance, and the more successful collisions with Hydrogen+ ions in the

Hydrochloric acid will be.

I predict that if the concentration is doubled the rate of reaction

will double. This is because they are directly proportional to each

other. Twice the concentration means twice the amount of Thiosulphate

particles there are. So collisions happen twice as often which means

all the Hydrochloric acid and Sodium Thiosulphate will react twice as

fast.

Sodium Thiosulphate + Hydrochloric acid →Sodium Chloride + Sulphur +

Sulphur dioxide + Water

Na2S2O3 (aq) + 2HCl (aq) → 2NaCl (aq) + S (s) + SO2 (g) + H2O (l)

Ionic Equation:

S2O3 (aq) + 2H (aq) → H2O (l) + S (s) + SO2 (g)

Results

Volume of Sodium Thiosulphate

(cm³)

Volume of Water

(cm³)

Time for Cross to disappear

(seconds)

1

Time

(sec )

Repeat time

(seconds)

Repeat 1