The rate of reaction is how quickly the chemical reaction takes place. During a reaction, we can measure how much of the reaction is taking place at different times. We can use graphs to show this.
The gradient of the line in a graph tells us how quickly the reaction is taking place. The steeper the slope, the faster the reaction.
Main Experiment
Aim: To find out about the aspects that affect the rates of reaction. I have chosen to vary the temperature because I think it will increase the reaction the higher and lower the temperature gets.
Theory:
- Temperature
- Surface
- Pressure
- Concentration
- Catalyst
Collision Theory:
A reaction occurs when particles collide. This process is based on random particle movement. So, therefore, the more particles you have in a space, the more likely they are to collide. Therefore making the reaction accelerate. This theory can be proved if you compare the rates of reaction with marble in hydrochloric acid. 'If the acid is of a higher concentration, the reaction will be quicker.'
The above factors affect the number of collisions of reactant particles, and this, in turn, affects the rate of the reaction. If the number of collisions per second increases then the rate of the reaction will increase. If a solution is made more concentrated, then there are more reactant particles per set volume. This makes collisions between the reactant particles more likely. Therefore there will be more collisions per second and as a consequence, more particles reacting per second. In other words, the rate of the reaction is increased.
Prediction: I predict that the higher the temperature, the more reaction there will be because the higher temperature will make the particles collide more frequently within the 60 seconds we are doing each experiment in.
We also want to see how a low temperature would affect our reaction. I predict this would be a slow reaction as the particles would have less energy to collide, therefore giving us a weak reaction.
Equipment:
- Eye goggles
- Gas syringe
- Marble chips (approx 2 grams per experiment)
- Hydrochloric acid - 10cm³ (2 Molar)
- Water
- Conical flask
- Bung and tube
- Stand
- Measuring cylinder
- Bunsen burner
- Gauze
- Heat proof mat
- Thermometer
- Boiling tube
Method: (See prelim method 2) I am going to experiment to find out the effect that temperature has on the reaction between hydrochloric acid and marble chips. I will do this by placing (+/- 0.05g) 2 grams of marble chips and some hydrochloric acid into a conical flask connected to a gas syringe through a bung and a tube. I will measure the amount of gas in the syringe every 10 seconds. I will heat up the acid with a water bath above a Bunsen burner and a thermometer to get the correct temperature. I will do 3 of each experiment of the following temperatures: 0, 10, 20, 30, 40, 50. We chose this range as it is the best range for the gas syringes we are using.
We will try and make this as fair test as we possibly can by keeping everything the same except the temperature. Hopefully, by keeping the concentration of the acid, mass and surface area as similar as possible in all our experiments, the accuracy and reliability of our results should be high.
Results:
Averages:
Conclusion:
In this experiment, the marble chips with the higher temperature acid reacted the quickest. The heaviest chips generally were also the quickest. This shows that the higher mass of marble chips and higher temperature of hydrochloric acid, the faster the reaction will take place.
Evaluation:
I think I could have improved this experiment by making it more of a fair test by having the exact mass of marble chips and exact surface area for each experiment. Some of the chips were slightly crushed which increases the surface area and speeds up the reaction making a huge difference. Apart from this, I think the experiment went fairly well.
