Investigation to find out how the rate of reaction between sodium thiosulphate and hydrochloric acid is affected by changing the concentration.

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Investigation to find out how the rate of reaction between sodium thiosulphate and hydrochloric acid

Investigation to find out how the rate of reaction between sodium thiosulphate and hydrochloric acid is affected by changing the concentration

Introduction

In this experiment I am going to find out how the rate of reaction between sodium thiosulphate and hydrochloric acid is affected by changing the concentration.

The equation to this is as follows:

Sodium +Hydrochloric À Sodium +Sulphur +Sulphur +water

Thiosulphate Acid Chloride Dioxide

Na₂S₂O₃ (aq) +2HCL (aq) À2NaCl(aq)+ S(s) +SO₂(g) + H₂o(l)

This reaction usually produces a yellow precipitate.

We place the reaction micture on a paper with a black cross drawn on it. When the cross is completely obscured, the reaction will have finished. The time taken for this to happen is the measure of the rate of reation. We must do this several times, and change the concentration of sodium thiosulphate.

The rate of reaction is a measure of the change which happens during a reaction in a single unit of time. The things that affect the rate of reation are as follows:

· Surface area of the reactants

· Concentration of the reactants

· The temperature at which the reaction is carried out

· Light

· Use of a catalyst

Rate of reaction = I/T

The factor which we are using is Concentration of the reactants.

Plan

Apparatus

· Conical flask

· Sodium thiosulphate (different concentrations)

· Hydrochloric acid (same concentration each time)

· Water (different concentrations)

· Stop watch

· Paper with black cross on it

· Small memiscus'

· A large memiscus

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Method

Firstly, we drew a black cross on a white piece of paper. Then, we put 10 cm₃ of hydrochloric acid in a conical flask (measuring the HCL with a small memiscus), and then put the conical flask on the black cross on the paper. We then added 50 cm₃ of sodium thiosulphate to the hydrochloric acid, and at this time we do not need to add any water. Immediately, we started the stopwatch.

We then waited for the black cross to be completely obscured by the mixture. When this happened we stopped the stopwatch. By this time the mixture ...

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