Investigating the factors that affect the rate of reaction.

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Chemistry Coursework 2003

Investigating the Factors that Affect the Rate of Reaction

By Chantelle Wright 11S

I, Chantelle Wright, declare that the work I

 have completed for assessment has been produced without

external assistance (apart from that which is acceptable under the scheme of assessment)

PLANING

Before actually planning the experiment, I will do some research to find out about the rates of reactions, and matters related to it, so that I can make predictions. And figure out a way to make this investigation fair and safe.

Planning ahead would help me find out how to do what and when, which should lead me to good results at the end of the experiment.

Aim

My aim is to investigate the factors that affect the rate of reaction. I will be seeing how the concentration of the hydrochloric acid affects the rate of reaction with magnesium ribbon. I have a limit of 30m of magnesium ribbon and 600cm3 of acid that can be used in my experiment.

Background Knowledge

The Collision Theory: A chemical reaction can only occur between particles
when they collide (hit each other). Particles may be atoms, ions or molecules.

There is a minimum amount of energy which colliding particles need in order to react with each other. If the colliding particles have less than this minimum energy, then they just bounce off each other and no reaction occurs. This minimum energy is called the energy. The faster the particles are going, the more energy they have. Fast moving particles are more likely to react when they collide. You can make particles move more quickly by heating them up (raising the temperature).

Changing the Rate of a Reaction: There are 5 ways to increase the rate of a chemical reaction. They are all understood in terms of Collision Theory (above)

The rate of a chemical reaction may be increased by
1)
.
2)
 (in solution).
3)
 (in gases).
4)
 of a solid.
5) Use a
.

The opposite of 1, 2, 3 and 4 will decrease the rate of reaction. A catalyst (strictly speaking) will change the rate of reaction. A catalyst can make a reaction go faster or slower. In practice, a catalyst is mainly used to make a reaction go faster.

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Variables: 

To create a fair test certain aspects of the experiment will have to be kept the same whilst one key variable is changed.  I have chosen to vary the concentration of the hydrochloric acid. This will give me a varied set of results from which I hope to make a decent conclusion.  If any of the non-variables below were not kept constant it would mean it would not be a fair test.  For instance if the magnesium ribbon was 1cm longer, the surface area of the ribbon would be larger and therefore the reaction with the hydrochloric acid would take longer. The variables of the experiment are as followed:

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  • For the purpose of my experiment I am going to do all the experiments at room temperature to make sure it is a fair test so that I will get accurate results. 
  • I will use exactly 2cms of magnesium ribbon each time to make sure that the surface area stays constant.
  • The volume of the solution will be kept fair by using 70cm3 each time.
  • The same strength acid of 1 unit will be used for each experiment.
  • I will take readings at equal intervals and keep the same duration for each experiment to make sure they all ...

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