The effect of temperature on rates of reaction
The aim of this experiment is to find out if the reaction rate of
sodium thiosulphate solution and hydrochloric acid will be affected by
a temperature change.
I predict that as a result of increasing the temperature of the sodium
thiosulphate, the rate of reaction will be faster. Because of the
increase in temperature, the particles will gain more kinetic energy.
This will therefore cause them to move faster and produce more
successful collisions, causing the rate to increase.
Na S O + 2HCl S + SO + 2NaCl + H O
Before carrying out the experiment, I must first of all begin the
preliminary work. This part of the experiment will enable me to choose
an appropriate scale of temperatures, and to decide upon the amount of
sodium thiosulphate solution that will be used (the concentration).
After doing this, I will then begin to carry out the experiment. I
will firstly put a measured amount of sodium thiosulphate solution
into a glass bottle, measure the temperature, and then add the
hydrochloric acid. Immediately afterwards I will seal the lid and put
it on top of a black mark, then start the stopwatch. I will observe
from above and when the black mark is no longer visible, I will stop
the stopwatch, measure the temperature again and record these
results. I will repeat the experiment a further two times to ensure
reliable results and continue this method for each temperature.
To make certain that my experiment will not be dangerous, I will carry
out some basic safety precautions. I will firstly ensure that there is
a safe working area around me by clearing the desks and removing
stools. I will then make sure that I am wearing safety glasses at all
times and handling the chemicals with care.
To keep a fair test, I will use the same amounts of hydrochloric acid
and sodium thiosulphate each time, keeping the black mark the same and
being accurate with all timings and measurements. I will also make
sure the apparatus is thoroughly cleaned before repeating the
experiment. The only thing I will be changing for each reaction will
be the temperature.
Diluted 5/5 with water
For the experiment I will use:
* Sodium Thiosulphate solution
* Hydrochloric acid
* A test tube
* A beaker
* A hot plate
* A thermometer
* A stopwatch
* A glass bottle
From my preliminary results graph, I could determine how I needed to
change the scale and concentration of my experiment. Using 10cm of
sodium thiosulphate, I quickly discovered that at 45 C the reaction
was too fast to measure and so for my scale to reach above that, I
needed to dilute the sodium thoisulphate. When I accordingly changed
the concentration to 5cm distilled water and 5cm sodium
thoisulphate. I noticed that I would be able to conduct the experiment
until 50 C because at 55 C it was only just measurable and this may be
a source of error if I wasn’t able...