"Complex" prac - Year 12

[kjf]

Hey everyone,

 

I have to figure out what prac I'm going to do as the big assessment for this year.

The text books we use have many pracs, but the teacher says we must go further than what's asked from the textbook.

 

So, flipping through the pages I see rates of reaction.

I get an idea.

 

What I want to do, is a prac which incorporates two main ideas:

 

How concentration affects rate of reaction

How temperature..

 

So, I would compare the two.

 

(have many test tubes) But essentially:

 

Have a test tube with high concentration and low temperature (lets say room temp). Have another test tube with the opposite: low concentration and high temperature.

 

The aim of the experiment would be to find a sort of ratio between concentration and temp.

 

As M increases, T decreases

 

eg: for 1M, T must decrease by 20 degrees.

 

To obtain the same rate of reaction, as the concentration increases, temperature must decrease.

 

 

 

So, I have two questions for you guys.

 

1. Do you think this is a good idea? It sort of combines two experiments from the text, AND goes further.

 

2. WOULD IT WORK? Would i be able to find a definite ratio?

 

Any help/info would be appreciated.

 

Thanks in advance

 

KJF

[hermanntrude]

there IS a relationship between concentration and rate, AND there is another relationship between temperature and rate.

 

Your experiment design involves changing both factors at once. perhaps you should be investigating the effect of temperature separately from the effect of concentration. I figure you'll need much more than 2 test-tubes

[thedarkshade]

How concentration affects rate of reaction

How temperature..

They both have the same effect. The speed up the reaction:

 

[math]v=[a]^n\times ^n[/math]

 

v - reaction speed

a & b - represent reactants

[]- represent concentration

n - represent the coefficient

[hermanntrude]

They both have the same effect. The speed up the reaction:

 

[math]v=[a]^n\times ^n[/math]

 

v - reaction speed

a & b - represent reactants

[]- represent concentration

n - represent the coefficient

 

not entirely true.

 

Some reactions are independant of the reactant's concentrations.

 

Temperature is also a slightly cloudy issue. All reactions are equilibria, but some equilibria lie so far shifted to the products that we consider them to be one-way reactions. The equilibrium constant is dependant upon temperature. Look up the Arrhenius equation.

[CaptainPanic]

I agree with Hermanntrude:

 

First do a set of experiments with identical concentration, but different temperatures.

Then a set with identical temperature, but different temperatures.

 

This way you learn about the individual parameters.