Investigating Rates of Reaction

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Investigating Rates of Reaction

HCL(aq)+Na2S203(aq) = 2NaCl(aq)+SO2(g)+S(s)+H2O(l)

Effects

To investigate the concentration of sodium thiosulphate solution we need to look at the factors affecting rate of reaction.

Temperature

When the temperature is increased the rate of reaction speeds up.

When the temperature decreases the rate of reaction slows down.

Concentration

When the concentration increases the rate of reaction increases.

When the concentration decreases the rate of reaction decreases.

Light Intensity

When the light intensity increases the rate of reaction increases.

When the light intensity decreases the rate of reaction decreases.

But light intensity only affects rate or reaction in photosensitive reactions; this reaction is not so therefore light intensity is not a factor we have to consider.

Catalyst

This provides a different route with a lower activation energy. But in this experiment there is no known catalyst, so we don't need to consider this factor,

Surface Area

When the surface area increases, the rate of reaction also increases, as there are more particles. But this is only in solids so this also is not a factor we need to consider, as neither reactants are solids.

Pressure

Neither reactants are gases, so pressure has no effect.

?Both solutions are colourless and water is also colourless so we can't measure colour change.

?SO2 is soluble in water, so we can't measure that.

?Sulphur appears as a yellow precipitate.

?The only thing we can do is time it for how long it will take for a marker to disappear.

Safety

HCL is corrosive so we must take care when using it. If it spills we must wash are hands if it came in contact and clear away immediately the surface.

Sodium Salt has minimal hazards, but it is harmful if ingested in quantity,

Sodium Dioxide is toxic, corrosive and poisonous so great care must be taken when using it.

Lab coats, lab coats and long hair must be tied back when using any of these substances.

Preliminary Experiment

We must find the best temperature and the volume and concentration of hydrochloric acid and sodium thiosulphate we need to use to carry out are investigation.

Heating acids is dangerous so we must not exceed 60oC
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We will use 1M HCL

1M Na2S203

M HCL 1M Na2S203 (both at 20 oC) time

20 cm3 20 cm3 12.0

too shallow, doesn't cover the cross

00 cm3 100 cm3 --------

too deep, can't see the cross at start

50 cm3 50 cm3 perfect 7.04

So to make results more accurate we must take more than 1 result and take an average. I will take 2 results. Also the same person must do all the experiments to keep them the same reaction time.

At any temperature higher ...

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