Chemical Reactions

Year 11 Science

Aim: To determine how the concentration of Hydrochloric acid affects the time taken for magnesium ribbon to disappear

Independent variable (What we are changing): Concentration of Hydrochloric Acid (HCl) Range: 100%, 80%, 60%, 40%, 20% of 2.0 M

Dependent variable (What we measure to record for results): Time take in seconds for magnesium ribbon to disappear.

Controlled variables (What will remain the same)

• Temperature of acid

• Volume of concentration

• Size of magnesium strip

• Same person timing

Equipment: • 5 Test tubes• 10 mL Test tube stand• 10 mL Measuring cylinder • Magnesium Ribbon• 50 mL beaker• Hydrochloric Acid 2.0 M• Water• Stop watch• Thermometer

Method: 1. Collect 5 Test tubes, Test tube stand, 50 mL Beaker, Thermometer, Measuring

cylinder, Stop watch and Bottle of hydrochloric acid (2.0 M)

2. Collect 10 pieces of magnesium ribbon, making sure they are exactly the same size.

3. Fill your beaker with tap water

4. Measure 5 mL of 2.0 M HCl using a measuring cylinder. Place in water bath to keep temperature constant.

5. Add Magnesium and record the time it takes to disappear. Start recording from the time you add the Mg to test tube and stop when it disappears (This is when the chemical reaction has finished)

6. Record Results in table.

7. Do steps 4,5 and 6 again to test for reliability

8. Test 80% concentration. Place 4 mL of 2.0 M HCl in a test tube and 1 mL of water. Place test tube in water bath.

9. Place Mg in Test tube and record from when you place it in the test tube until it has disappeared. - Record results

10. Repeat steps 8,9,10 again to test for reliability

11. Repeat steps 8,9,10 and 11 for 60% concentration, 40% Concentration and 20% concentration.

Milliliters of 2.0 Mol Hydrochloric

Acid

Milliliters of Water

Concentration of 2.0 M Hydrochloric acid in

Percentage (%)

5 mL 0 mL 100%

4 mL 1 mL 80%

3 mL 2 mL 60%

2 mL 3 mL 40%

1 mL 4 mL 20%

Concentration Table:

Results Table:

Time taken for Magnesium strip to

disappear (seconds)

Concentration of 2.0 M HCl

Test 1 Test 2 Test 3 Average

100%

80%

60%

40%

20%

Graph Results:

Time taken for Magnesium to dissapear in different concentrations of 2.0 M HCl

0

20

40

60

80

100

120

100% 80% 60% 40% 20%

Percentage Concentration of 2.0 M Hydrochloric Acid

Tim

e (S

econ

ds)

Time

Conclusion: Needs to state what happened in the results and how we know that it happened

Example: These results show the higher the concentration of 2.0 Mol Hydrochloric Acid the faster the magnesium ribbon disappeared and therefore the faster the rate of reaction. The results show this clearly with the magnesium ribbon disappearing in _____seconds at the 100% concentration of 2.0 M Hydrochloric acid compared to the magnesium ribbon disappearing in ____ seconds at the 20% concentration of 2.0 M Hydrochloric acid.

Justification: Explanation of why you did what you did during the method

• I used 5 different concentrations of Hydrochloric acid so that I can have accuracy in my data as the more tests I complete the more data I have to review

• 1 only had one reaction going at a time to ensure that I correctly timed the reaction

• I used the same equipment to ensure their were no differences in the measuring

• I was the only one doing the experiment to keep the measuring and timing of the experiment the same.

• I measured the magnesium so that they were all the same size so that the size of Mg was not a factor in the investigation.

• We used a water bath to keep the temperature of the reaction the same

Collision THEORY

Discussion – Relate the finding from your investigation to the particle collision theory of reaction:

The higher the concentration of Hydrochloric acid the more particles there are in the 5 milliliters of concentrate to collide with the magnesium, this means the chance of collision is greater which mean higher change o f effective collision. The higher the chance of collision between the Hydrochloric acid and the magnesium, the faster the reaction will be completed