gas distance travelled / cm ammonia 36 hydrogen chloride 24 The table records how far ammonia gas and hydrogen chloride gas each travelled along a tube befo...
Question 1 Report
| gas | distance travelled / cm |
|---|---|
| ammonia | 36 |
| hydrogen chloride | 24 |
The table records how far ammonia gas and hydrogen chloride gas each travelled along a tube before a white ring formed where they met. Which statement is best supported by these distance measurements?
Answer Details
Both gases set off at the same moment from opposite ends and stopped travelling at the same moment, when they met and formed the white ring. Since the times are equal, the distances directly compare their speeds.
The measurements show 36 cm travelled by ammonia against 24 cm by hydrogen chloride, so ammonia diffused faster, as it travelled the greater distance. The reason is its lower relative molecular mass, 17 against 36.5, which gives its molecules a higher average speed at the same temperature.
Claiming hydrogen chloride went further misreads the table, since 24 cm is the smaller value. Equal rates would have produced two equal distances of 30 cm each. And both gases plainly moved, otherwise no ring could have formed at all. Equal time is the hidden condition that makes distance a fair measure of rate.
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