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This question is about properties of materials - Edexcel - GCSE Chemistry Combined Science - Question 7 - 2016 - Paper 1
Question 7
This question is about properties of materials. (a) Figure 6 shows some properties of steel and Kevlar®: | property | steel | Kevlar® | |-----------------... show full transcript
Worked Solution & Example Answer:This question is about properties of materials - Edexcel - GCSE Chemistry Combined Science - Question 7 - 2016 - Paper 1
Step 1
Calculate the surface area to volume ratio of this cube of silver.
Answer
To calculate the surface area to volume ratio of a cube, we first need to find both the surface area and the volume.
For a cube with side length , the surface area (SA) can be calculated using the formula: For a cube of silver with each side measuring 2 cm:
Next, we calculate the volume (V) using the formula: Thus:
Now we can find the surface area to volume ratio using the formula:
Step 2
Suggest an explanation of why a given mass of silver is more effective as a catalyst when used as nanoparticles rather than in a powder form.
Answer
Using silver in nanoparticle form increases its effectiveness as a catalyst for several reasons:
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Increased Surface Area: Nanoparticles have a much larger surface area relative to their volume compared to larger materials. This increased surface area allows for more active sites where reactions can occur.
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Enhanced Reactivity: The larger surface area facilitates more interactions between catalyst and reactants, significantly enhancing the rate of the catalytic reactions on the surface of the nanoparticles.
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Lower Activation Energy: The smaller size of nanoparticles can affect the energy landscape of reactions, potentially lowering the activation energy required for the reactions to proceed.
Therefore, when silver is used in nanoparticle form, more of it is available to react with the substances it is catalyzing, thereby increasing its overall catalytic activity.