Reaction Between Sodium Thiosulphate And Hydrochloric Acid Lab Report

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A kinetic study of the reaction between aqueous sodium thiosulphate and hydrochloric acid

Aim: To carry out a complete kinetic study of the reaction between aqueous sodium thiosulphate and hydrochloric acid:

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

PART A

To deduce the order of the reaction with respect to the concentrations of sodium thiosulphate and hydrochloric acid the experiment will be carried out at constant temperature and the time interval between the addition of HCl and the obscuring of the ink cross on white paper by the solid yellow sulphur precipitate will be measured for a constant volume of solution that uses 3 varying concentrations of Na2S2O3(aq) while maintaining the concentration of HCl(aq) …show more content…

This is given by the equation: Rate = Amount of sulphur

Time

The amount of sulphur needed to obscure the cross is assumed to be the same in each reaction so therefore,

Rate = 1

Time

Then, the data will be placed in a table to determine the effect of concentration on the rate of reaction and hence the order of both reactants can be formed. Adding up both orders of the reactants gives the overall order of the reaction.

PART B

To find out the effect of temperature on the rate of the reaction the time interval between the addition of HCl and the obscuring of the ink cross on white paper by the solid yellow sulphur precipitate at five different temperatures must be recorded. A graph showing time taken vs. temperature will produce a curve showing the effect of varying temperature on the rate of reaction.

The Arrhenius equation ln k = ln A – (Ea / RT) can be shown graphically by plotting a graph of ln (t) against ln (1/T). The gradient of this graph = - (Ea / RT) which can be used to calculate activation energy. The y-intercept of the line = ln A where A is the
Arrhenius constant for the …show more content…

Many factors affect the rate of a reaction, one of which is concentration. For any reaction to happen, the reactant particles must first collide. This is true whether both particles are in solution, or whether one is in solution and the other is a solid. If the concentration is higher, there are more particles in the same volume so the chances of collision are greater therefore the rate of reaction increases. However, this is not always the case because the rates of most reactions can be related to the concentrations of individual reactants by the rate law: Rate = k[X]n (where ‘n’ gives the order of the reaction). This expression can only be determined experimentally and cannot be predicted from the balanced equation or in any other way. So if the concentration of one of the reactants is doubled and the rate also doubles, the order of reaction (with respect to that reactant) is 1, because it shows that rate is proportional to concentration to the power 1. If the concentration of one of the reactants in doubled and the rate is four times greater, the order

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