How changing the concentration changes the rate of reaction.

How changing the concentration changes the rate of reaction.

Introduction

We are going to look at the following factors during this

investigation:

1 Why altering rate could be an advantage

2 Good ideas to control the rate of reactions

3 Briefly mention the factors that can change the rate of reaction

such as: -

Temperature

Surface Area

Catalyst

Concentration

I am going to find out if changing the concentration of nitric acid in

water and see if it has any effect on changing the rate of which

precipitate is formed when reacts with sodium thiosulphate.

Prediction

I think that a faster reaction will happen with a higher acid

concentration as there will be more successful collisions with sodium

thiosulphate, which will result in a faster reaction because the

product will be produced quicker.

Apparatus

1 Conical Flask

2 Beakers

3 Measuring Cylinders

Paper with a black cross on

Stopwatch

Nitric Acid

Sodium Thiosulphate

Water Safety Glasses

Method

For my experiment I will measure out 25cm³ of Sodium Thiosulphate and

put it in a conical flask. I will put the flask on top of a piece of

paper that has a black cross drawn on it. I will then measure 15cm³ of

Nitric Acid and add this to the Sodium Thiosulphate in the conical

flask. The two should react together to make a cloudy precipitate and

we are going to time how long it takes for the liquid to turn cloudy

until we can’t see the cross underneath the glass anymore. We are

going to carry this experiment out a number of times but each time we

will decrease the volume of Nitric Acid by 1cm³ and add 1cm³ of water.

Each time we will decrease the Nitric Acid and increase the volume of

water to see which one holds the fastest reaction. Our final amount of

Nitric Acid should be 5cm³ and 10cm³ of water. I will repeat the

experiment 3 times to make sure that my results are as accurate as

they can be. I will then record my results onto a graph so I can

compare them better and make a line of best-fit graph to show my

results even clearly.

How will I make it a fair test?

To make sure that my experiment is fair I will always use the same

amount of Sodium Thiosulphate and the only factor I will change will

be the volume of Nitric Acid and water but only to total 15cm³ so the

depth of the liquid will always be the same. Also, I will always use

the same conical flask and wash it out after every time I have used

it.

Evaluation

First of all we put our safety goggles on, and then we added 25cm3 of