The Effect of Concentration on the Rate of Reaction Between Hydrochloric Acid and Sodium Thiosulphate

The Effect of Concentration on the Rate of Reaction Between Hydrochloric Acid and Sodium Thiosulphate

Introduction

In this experiment we are going to react Hydrochloric Acid with Sodium

Thiosulphate. We are going to see what effect the concentration of

Hydrochloric Acid has on the rate of reaction. We are going to keep

the concentration of the Sodium Thiosulphate constant. We are going to

vary the concentration of the Hydrochloric acid. The total volumes of

the two solutions will remain constant therefore keeping the overall

volume constant.

[IMAGE]Na2S2O3 + 2Hcl S + SO2 + 2NaCl + H2O

Scientific Knowledge

Particles, such as molecules, atoms or ions, must collide before a

chemical reaction can take place. This diagram shows this:

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Low Concentration

High Concentration

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[IMAGE][IMAGE]So the increase in concentration means increase in rate

of reaction. If you doubled the concentration you would also double

the amount of the product that is produced.

This is explained in our textbook Longmans GCSE chemistry:

"If you increase the concentration of the reactants, the reaction

becomes faster. Increasing the concentration increases the chances of

particles hitting each other"

[IMAGE]Prediction

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As the concentration increases the rate of reaction increases because

of the scientific knowledge shown above.

Safety

* Lab coats are to be warn as spillages may occur

* Safety glasses must be worn as we are using acid

* If any glass is broken tell the teacher immediately

* Wipe up any spillages and then wash your hands.

Preliminary Work

We are going to have to do some preliminary work so that we can decide

what ranges we are going to do and if there is anything we can do to

improve the method to make it more accurate.

Preliminary Method

1. Measure out the Sodium Thiosulphate using a measuring cylinder.

2.