I need to keep the volume of solution of acid the same because there will be more of the acid to continue reaction even though the concentrations are the same, so it will be unfair if one of the tests had more solution to dissolve the magnesium. I will keep this the same by using same volumes of solution.
I need to keep the temperature of the solution and the surroundings the same because the higher the temperature the quicker the particles of acid can move and collide with the magnesium ribbon and therefore increase rate of reaction, so it will be unfair if one of the tests had a different temperature as it can decrease or increase the rate of reaction according to the increase or decrease of temperature.
I need to keep the same acid for the solution because different acids have different strengths; it will be unfair if I used a stronger acid because that will increase the rate of reaction. To keep this factor the same I will use hydrochloric acid only.
I am going to change the concentrations of the acid by mixing it with water. By using 2M hydrochloric acid I will take 40 ml of it to create a 2M concentration.
30ml of hydrochloric acid and 10ml of water to create a 1.5M concentration.
20ml of hydrochloric acid and 20ml of water to create a 1M concentration.
10ml of hydrochloric acid and 30ml of water to create a 0.5M concentration.
EQUIPMENT
2M Hydrochloric acid
Tap water
Measuring cylinder
12 beakers
Magnesium strip
Scissors
Ruler
Timer
PLANNED METHOD
- Collect all the equipment
- Measure out 10cm of magnesium ribbon and cut it. Collect 8 pieces of 10cm magnesium ribbon
- Measure out 40ml of hydrochloric acid in a measuring cylinder
- Pour it into a beaker
- Put the magnesium ribbon into the acid solution and time how long it takes for the magnesium ribbon to completely disappear
- Record
- Repeat steps 3-6 with concentrations of 1.5M hydrochloric acid, 1M hydrochloric acid, 0.5M hydrochloric acid. Collect 3 of each for an average
ACTUAL METHOD
1. Collect all the equipment
2. Measure out 2cm of magnesium ribbon and cut it. Collect 8 pieces of 10cm magnesium ribbon
3. Measure out 40ml of hydrochloric acid in a measuring cylinder
4. Pour it into a beaker
5. Put the magnesium ribbon into the acid solution and time how long it takes for the magnesium ribbon to completely disappear
6. Record
7. Repeat steps 3-6 with concentrations of 1.5M hydrochloric acid, 1M hydrochloric acid, and 0.5M hydrochloric acid. Collect 3 of each for an average
There were little changes I made from my planned method. The only thing I changed was reducing the 10cm piece of magnesium ribbon to 2cm. This is because 2cm of magnesium ribbon will be faster for the limited time I have to be dissolved.
TABLE OF RESULTS
GRAPH
CONCLUSION
By looking at my graph and table of results I can clearly see that the rate of reaction increases at the concentration of acid increases. This is because where there is less time needed for the same reaction to take place the faster the rate of reaction. This agrees with my hypothesis. I have found out that the as the concentration of acid increases so does the rate of reaction. This is because in a stronger concentration, there are more acid particles within the same amount of solution and therefore the more frequent the collisions with the reactant’s surface area.
EVALUATION
By looking at my graphs and results I can see generally the trends of results are very good with a very low error range. However, I do have a single rogue result that I have taken out of the average to create a more accurate graph. My method was generally good, nothing went wrong and all went as planned. Although the drop of time needed to dissolve the magnesium ribbon was more dramatic from 0.5M to 1M, I can still clearly see that a strong negative correlation is in place.
There were some errors in this investigation. The strip of magnesium may have been uneven and even if I had cut it perfectly to 2cm, the masses may still be different; this could have caused inaccurate results.
Moreover, it is difficult to judge when the magnesium is completely dissolved. This could have caused a few seconds of inaccuracy as it is hard to determine when to stop timing.
To take this experiment further, I can use the syringe and find the gas loss of the reaction between the hydrochloric acid and magnesium. I could record the gas loss within a certain amount of time. This will be a much more accurate way of measuring this data.