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Water, acidified with sulfuric acid, is decomposed by electrolysis - Edexcel - GCSE Chemistry Combined Science - Question 2 - 2019 - Paper 1
Question 2
Water, acidified with sulfuric acid, is decomposed by electrolysis. The water is decomposed to produce hydrogen and oxygen. (i) A sample of hydrogen is mixed with a... show full transcript
Worked Solution & Example Answer:Water, acidified with sulfuric acid, is decomposed by electrolysis - Edexcel - GCSE Chemistry Combined Science - Question 2 - 2019 - Paper 1
Step 1
State what would happen.
Answer
When a sample of hydrogen is mixed with air and ignited, it will react explosively with oxygen in the air to produce water vapor. This reaction is highly exothermic, and the combustion generates a significant amount of heat and light, producing a loud pop sound.
Step 2
Describe, using the data in Figure 2, what the results show about the volumes of hydrogen and of oxygen produced in this experiment.
Answer
The data in Figure 2 shows a consistent relationship between the volumes of hydrogen and oxygen produced during electrolysis. As hydrogen gas is collected, the volume of oxygen produced is half that of hydrogen, indicating a 2:1 ratio between hydrogen and oxygen. For example, at 0 minutes, both volumes are 0; at 2 minutes, 4 cm³ of hydrogen corresponds to 2 cm³ of oxygen; and this pattern continues throughout the experiment. This confirms that hydrogen is produced at twice the volume of oxygen, reinforcing the underlying chemical principle that in the decomposition of water, two volumes of hydrogen gas are generated for every volume of oxygen.