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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, a combustion reaction occurs. This reaction will produce water vapor and release energy in the form of heat and light. The reaction can be represented by the equation: This indicates that two volumes of hydrogen will react with one volume of oxygen to produce water.
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 the relationship between the volume of hydrogen and the volume of oxygen produced during the electrolysis of water. At the start of the experiment, no gases are produced at time 0.
- At 2 minutes, 4 cm³ of hydrogen is produced along with 2 cm³ of oxygen.
- By 4 minutes, the volume of hydrogen increases to 8 cm³, while the oxygen volume doubles to 4 cm³.
- At 6 minutes, the hydrogen volume reaches 12 cm³ and the oxygen volume is at 6 cm³.
- Finally, at 8 minutes, the volume of hydrogen decreases to 6 cm³, and the oxygen volume is 8 cm³.
These results indicate a consistent ratio of hydrogen to oxygen production, demonstrating that for every 2 volumes of hydrogen produced, there is 1 volume of oxygen, reflecting the 2:1 ratio of hydrogen to oxygen in water. This supports the observation that hydrogen is produced at a rate double that of oxygen.