Chemical Reactions and Equations | Activity 1.7 with Solution

Activity 1.7


  • Take a plastic mug. Drill two holes at its base and fit rubber stoppers in these holes. Insert carbon electrodes in these rubber stoppers as shown in Fig. 1.6.
  • Connect these electrodes to a 6 volt battery.
  • Fill the mug with water such that the electrodes are immersed. Add a few drops of dilute sulphuric acid to the water.
  • Take two test tubes filled with water and invert them over the two carbon electrodes.
  • Switch on the current and leave the apparatus undisturbed for some time.
  • You will observe the formation of bubbles at both the electrodes. These bubbles displace water in the test tubes.
  • Is the volume of the gas collected the same in both the test tubes? (No)
  • Once the test tubes are filled with the respective gases, remove them carefully.
  • Test these gases one by one by bringing a burning candle close to the mouth of the test tubes.
  • What happens in each case?
  • Which gas is present in each test tube?

Answer:

When we bring a burning candle to the gas at cathode, it burns immediately. But gas at anode does not burn.

At
cathode (-ve electrode), hydrogen gas is collected. At anode (+ve electrode), oxygen is collected.

At cathode, double amount of gas is collected as compared to anode because during the break down of water, 2H molecule is released with 1 oxygen molecule.
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