大象传媒

Apparatus and chemicals

  • 200 cm3 of 2 mol/dm3 hydrochloric acid and deionised water
  • 10 x 3 cm strips of magnesium
  • 100 cm3 beaker, 250 cm3 beaker, watch glass, measuring cylinder (25 cm3)
  • Stop clock

Method

  1. Carefully collect 200 cm3 of hydrochloric acid using the 250cm3 beaker, and 10 strips of magnesium using a watch glass.
  2. Using the measuring cylinder, measure out 25 cm3 of hydrochloric acid and add to the small beaker. Remember to use the measuring cylinder accurately.
  3. Drop the piece of magnesium ribbon into the beaker and start the stop watch, swirl once to ensure the magnesium is fully coated in the acid. Stop the watch when all the magnesium disappears.
  4. Repeat the experiment to ensure reliability of results.
  5. Repeat steps 2-4 except using a total of five different volumes of acid and water to ensure different concentrations of acid. The proportions you need to use are given in the results table:
Volume of hydrochloric acid / cm3Volume of deionised water / cm3Time taken for magnesium to disappear / sTime taken for magnesium to disappear / sTime taken for magnesium to disappear / s
鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌12Average
250鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌
205鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌
1510鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌
1015鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌
520鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌
Volume of hydrochloric acid / cm3鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌
Volume of deionised water / cm3鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌
Time taken for magnesium to disappear / s1
Time taken for magnesium to disappear / s2
Time taken for magnesium to disappear / sAverage
Volume of hydrochloric acid / cm325
Volume of deionised water / cm30
Time taken for magnesium to disappear / s鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌
Time taken for magnesium to disappear / s鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌
Time taken for magnesium to disappear / s鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌
Volume of hydrochloric acid / cm320
Volume of deionised water / cm35
Time taken for magnesium to disappear / s鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌
Time taken for magnesium to disappear / s鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌
Time taken for magnesium to disappear / s鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌
Volume of hydrochloric acid / cm315
Volume of deionised water / cm310
Time taken for magnesium to disappear / s鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌
Time taken for magnesium to disappear / s鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌
Time taken for magnesium to disappear / s鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌
Volume of hydrochloric acid / cm310
Volume of deionised water / cm315
Time taken for magnesium to disappear / s鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌
Time taken for magnesium to disappear / s鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌
Time taken for magnesium to disappear / s鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌
Volume of hydrochloric acid / cm35
Volume of deionised water / cm320
Time taken for magnesium to disappear / s鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌
Time taken for magnesium to disappear / s鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌
Time taken for magnesium to disappear / s鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌

Analysis of results

In this experiment we can use the times to calculate an approximate value for the rate of each reaction by using the formula:-

\(Rate~= \frac {1}{time}\)

Using your average times calculate the rate of reaction for each experiment:-

Average time / sRate / s-1
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鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌
鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌
鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌
鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌
Average time / s鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌
Rate / s-1鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌
Average time / s鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌
Rate / s-1鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌
Average time / s鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌
Rate / s-1鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌
Average time / s鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌
Rate / s-1鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌
Average time / s鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌
Rate / s-1鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌鉅赌

We can also calculate the percentage of acid used, or, since we know the original concentration of the acid is 2 mol/dm3, we can calculate the concentrate for each experiment:-

Volume of acid / cm3Percentage acidConcentration /mol/ dm3
251002.0
20801.6
15601.2
10400.8
5200.4
Volume of acid / cm325
Percentage acid100
Concentration /mol/ dm32.0
Volume of acid / cm320
Percentage acid80
Concentration /mol/ dm31.6
Volume of acid / cm315
Percentage acid60
Concentration /mol/ dm31.2
Volume of acid / cm310
Percentage acid40
Concentration /mol/ dm30.8
Volume of acid / cm35
Percentage acid20
Concentration /mol/ dm30.4

Finally, we can plot a graph of our Independent Variable (x-axis) against our Dependent Variable (y-axis). Your Independent Variable will be either % Acid, or Concentration. Your Dependent Variable will either be time or rate. Your teacher will instruct you on which to use.