A student used the apparatus in Figure 7 to investigate the rate of the reaction between a metal and dilute hydrochloric acid - Edexcel - GCSE Chemistry Combined Science - Question 5 - 2022 - Paper 1
Question 5
A student used the apparatus in Figure 7 to investigate the rate of the reaction between a metal and dilute hydrochloric acid.
Pieces of the metal were placed in di... show full transcript
Worked Solution & Example Answer:A student used the apparatus in Figure 7 to investigate the rate of the reaction between a metal and dilute hydrochloric acid - Edexcel - GCSE Chemistry Combined Science - Question 5 - 2022 - Paper 1
Step 1
Name a piece of apparatus that would be better to measure the volume of gas produced, instead of the 250 cm³ measuring cylinder.
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Answer
A more suitable piece of apparatus is a gas syringe. It provides a more accurate measurement due to smaller graduations and a higher resolution, allowing for more precise readings of the gas volume.
Step 2
Calculate the mean rate of production of hydrogen over the first 90 seconds, in cm³ per second.
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Answer
To find the mean rate, we first determine the volume of gas produced at 90 seconds, which is approximately 29 cm³. The mean rate of production can be calculated using the formula:
extrate=time (seconds)total volume=9029≈0.322cm3per second
Step 3
State why the measurements could have been stopped at 9 minutes.
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Answer
The measurements could have been stopped at 9 minutes because the volume of gas produced would have reached a plateau or leveled off, indicating that the reaction had slowed or stopped.
Step 4
Explain why the rate of reaction increases when the concentration of acid is increased.
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Answer
When the concentration of acid increases, there are more acid particles in a given volume. This leads to more frequent collisions between the acid particles and the metal, resulting in a higher frequency of successful reactions, thereby increasing the rate of reaction.
Step 5
Which one is correct?
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Answer
The correct option is D: use the same metal but in a powdered form. Powdered materials have a larger surface area that allows for more collisions with the acid, thus increasing the reaction rate.
Step 6
Describe how the student can make small and medium sized marble chips from large chips.
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Answer
The student can crush the large chips using a pestle and mortar to break them down into smaller pieces. Sifting the crushed marble through a sieve can help separate the smaller sized chips from the larger ones. For medium chips, the student can adjust the crushing time or repeat the process to get the desired sizes.
