Surface Area
The greater the surface area of the reactants the more particles there are available for a successful collision.
A Catalyst
A catalyst is a substance that changes the rate of a chemical reaction but remains chemically unchanged it self.
Concentration
Concentration effects the rate of a reaction because the higher the concentration of particles the greater the chance of a successful collision. The general trend for the concentration is the rate doubles as the concentration doubles (they’re directly proportionate).
Activation energy
What is Activation energy? It is the amount of energy required for the reactants to successfully react. The reactants need a certain amount of energy,
Any extra energy increases they’re chance of a successful collision.
Hypothesis
Prediction
I predict that as the molarity increases, the speed of the reaction will increase, therefore the magnesium will dissolve quicker. I believe this because most chemical reactions happen faster when the concentration of acid higher. At higher concentrations the molecules will dissolve quicker, which makes it easier for them to react together. Usually increases of 1molar will double the rate of reaction.
Chemical reactions take place by chance. Particles need to collide with enough velocity so that they react. As concentration is increased the particles react faster as they have more energy. This means that they are colliding more often and more of the collisions have enough velocity to cause a reaction. Since there are more collisions the chemical reaction takes place faster.
I am going to conduct the experiment using five different concentrations of acid, shown in this table:
The concentration of acid we were allowed to use was 10cm3 (2 Molar)
I am going to take three readings for each concentration, which will give me a fair set of results, and I will be able to work out an average set of results.
Apparatus
I have chosen to use two 10cm3 measuring cylinders, one to measure the volumes of acid and the other to measure the volumes of water, I decided to use a measuring cylinder and not a pipette because a measuring cylinder is more accurate than a pipette. I am going to use fifteen test tubes, all the same size as to keep the experiment fair, and I will use a stop clock to measure how long it takes for the magnesium ribbon to dissolve.
Safety
We will be using acid, so at all times we must be very careful and we must wear goggles. If any spills onto our hands it should be washed off immediately and reported to the teacher.
Plan
I am going to investigate how concentration strength affects the rate of reaction between magnesium ribbon and nitric acid. The procedure for the experiment is as follows:
- Using a measuring cylinder measure out the correct quantities of both nitric acid and water, as to make up the solutions.
- Place the solutions into the fifteen test tubes.
- Label the test tubes so that you no which solution is which
- Measure out and cut 1cm of magnesium ribbon.
- Get stop clock ready.
- Place the magnesium ribbon into the first solution (2 Molar), and time how long it takes to dissolve.
- Record the results in the table.
- Repeat the experiment with the same solution (2 Molar) two more times, for accuracy.
- Repeat the experiment for solutions, 1.6 Molar, 1.2 Molar, 0.8 Molar and 0.4 Molar
Variables
The variables in this experiment are:
-Temperature
-Concentrations used
-Size of test tubes
-Size of magnesium ribbon
If the temperature is to hot or to cold the reaction will either take place to quickly, or it wont happen, so to keep this fair I will conduct all experiments at room temperature.
The maximum amount of acid we are allowed to use is 10cm3, which is 2 Molar, and if there is no acid in the solution the magnesium ribbon will not dissolve at all, so there needs to be at least 2cm3 of acid in the concentrations.
I will use the same size test tubes throughout the experiment, if they are to big, the solution will not take up enough surface area, and will not cover the magnesium ribbon.
For the size of magnesium ribbon, I decide to use 1cm because this is not to big that the solution will not cover it, and it is not to small that we are not able to see it.
Method
After deciding how to approach all of the variables in the experiment I decided how to carry out my experiment. I decide to use different concentrations of nitric acid in 2 Molar, 1.6 Molar, 1.2 Molar, 0.8 Molar and 0.4 Molar (1 mole/dm). To obtain these solutions I mixed the nitric acid with water, the correct amounts are shown I this table:
I then put these solutions into test tubes and labelled them. I decided to start with the 2 molar solution, I placed the magnesium ribbon into the first of the “ molar test tubes, and timed how long it took to dissolve, I then recorded the results in the table. I did this three times for each of the concentrations.
Results
To obtain the best possible results I carried out each of the experiments on each of the solution 3 times, this gave me a set of fifteen results, and I was then able to work out an average result for each of the concentrations. These are my table of results:
Discussion
