Question
(c) Electrolysis of hydrochloric acid can produce hydrogen and chlorine. The apparatus for the electrolysis is hydrochloric acid two carbon rods a suitable container for the electrolysis reaction a suitable source of electricity test tubes Describe how the apparatus can be used to electrolyse hydrochloric acid and how the gases produced can be tested to show that they are hydrogen and chlorine. You may use a diagram to help your answer.
Answer
4.1
(209 Votes)
Fletcher
Veteran · Tutor for 12 years
Answer
1. Set up the apparatus with hydrochloric acid, two carbon rods, a suitable container, a suitable source of electricity, and test tubes.2. Connect the power supply to the carbon rods (electrodes).3. During electrolysis, chlorine gas is produced at the anode and hydrogen gas at the cathode.4. Collect the gases in inverted test tubes.5. Test for hydrogen gas by bringing a lit splint close to the test tube; it will produce a 'pop' sound.6. Test for chlorine gas by bringing damp blue litmus paper close to the test tube; it will bleach the paper.
Explanation
## Step 1: Set up the apparatus for electrolysis.- Fill the suitable container with hydrochloric acid (
).- Insert two carbon rods (electrodes) into the hydrochloric acid. Ensure they are connected to a suitable source of electricity (battery or power supply).- Place inverted test tubes over each electrode to collect the gases produced during electrolysis.## Step 2: Connect the power supply.- Connect the positive terminal of the power supply to one carbon rod (anode) and the negative terminal to the other carbon rod (cathode).## Step 3: Electrolysis process.- When the power supply is turned on, electrolysis of hydrochloric acid occurs.- At the anode (positive electrode), chloride ions (
) are oxidized to produce chlorine gas (
).- At the cathode (negative electrode), hydrogen ions (
) are reduced to produce hydrogen gas (
).### **Oxidation reaction at the anode:**
### **Reduction reaction at the cathode:**
## Step 4: Collect the gases.- The chlorine gas (
) produced at the anode will be collected in the test tube placed over the anode.- The hydrogen gas (
) produced at the cathode will be collected in the test tube placed over the cathode.## Step 5: Test for hydrogen gas.- Remove the test tube containing the gas collected at the cathode.- Bring a lit splint close to the mouth of the test tube. If the gas is hydrogen, it will produce a 'pop' sound when it ignites.## Step 6: Test for chlorine gas.- Remove the test tube containing the gas collected at the anode.- Bring a piece of damp blue litmus paper close to the mouth of the test tube. If the gas is chlorine, the litmus paper will be bleached (turn white).