The reaction rate is affected by:
Concentration of reactions,
Surface area, the marble chips are different sizes
Adding a catalyst,
Amount of reactants.
My aim is to find out how different concentrations of hydrochloric acid reacts with marble chips.
For this test I used 4 marble chips, 20ml of hydrochloric acid and a 100ml measuring tube full of water. My aim is to find out how long it takes gas to fill up the tube by timing it until all the water has gone from the tube. The gas is produced by 4 marble chips been put in the acid which produces gas.
This is a preview of the whole essay
Hydrochloric acid + calcium carbonate --> calcium chloride+ carbon dioxide.
Sceintific knowledge that will help with my prediction:
> When a reaction occurs the particles of two reations must collide.
> A much more conentrated solution has more particles per cm /ml.
> So, if there are more particles in both solutions and solid the particles will be able to collide more easily and so, making the reaction quicker.
> The particles must have a lot more energy so that they move fast and when they collide with each other they don't just brush past each other.
I predict that it will take longer for the gas to collect up in the tube as the acid becomes less concentrated because it would be reducing the amount of particles in the acid not making it able to make the reaction faster.
Step by step method:
* Set up the apparatus as shown in the diagram.
* Measure 20ml of hydrochloric acid in the tube and pour into the chronical flask.
* Then place the 4 marble chips in the acid and the bung on top.
* Fill the tube with water and place the conection tube under it so gas can collect in the tube.
* Time how long it takes the gas to collect up from 100ml to 50ml.
* Then record my results from doing the test twice and then work out my average from thr results
* Then I shall write a conclusion about what I have found ou and noticed.
8ML ACID, 2ML WATER
6ML ACID, 4 ML WATER
4ML ACID, 6ML WATER
2ML ACID, 8ML WATER
I have found out that my prediction was correct and that the more acid in there is the less amount of time it takes the water to go down. The pattern in my graph supports my prediction and that it is true as the line of best fit shows that the less concentrated the acid the more time it takes. This is because there are more particles in a concentrated solution and the particles are able to collide more easily, but the particles must have a lot of energy so they do not just tap each other when they collide. The particles help speed up the reaction. My results do back up my prediction because my prediction explains that of what my results show.
Here's what a teacher thought of this essay
** Planning The candidate has carried out an experiment to investigate the effect of changing concentration on rate of reaction. The experiment was planned with a stated hypothesis and a clear idea of how this was to be tested. The planned method was lacking in key scientific details and failed to ensure all the key variables were controlled. Carrying out The candidate carried out a reasonable number of repeats on an acceptable range of the independent variable but the recording of results was poor with lack of clear headings and units in the table. The graph was not included. Analysis and Evaluation The report's conclusion is limited and there was no evaluation used to look at the method used and to suggest improvements. The conclusion would be improved by linking it more closely to the aim of the experiment, stating the effect of concentration on rate of reaction.