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This question is about properties of materials - Edexcel - GCSE Chemistry - 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 - Question 7 - 2016 - Paper 1
Step 1
Explain two reasons why Kevlar® is preferred to steel as the material for body armour.
Answer
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Higher Relative Strength: Kevlar® has a relative strength of 5 compared to steel's relative strength of 1. This means that for a given weight, Kevlar® can withstand greater forces, making it more effective in protecting against impacts.
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Flexibility: Kevlar® is noted for its high flexibility compared to the low flexibility of steel. This property allows for better mobility and comfort in body armour, essential for the wearer’s movement and agility.
Step 2
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 the formulas for surface area and volume.
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Surface Area (SA) of a cube = 6 × (side length)². For a side length of 2 cm:
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Volume (V) of a cube = (side length)³. For a side length of 2 cm:
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Surface Area to Volume Ratio (SA/V):
Step 3
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
Nanoparticles of silver have a significantly larger surface area relative to their volume compared to larger powder forms. This increase in surface area allows for more active sites where reactions can occur, enhancing the effectiveness as a catalyst. Moreover, the unique properties of nanoparticles, such as increased reactivity and the ability to interact with reactants more efficiently, contribute to their superior catalytic performance. Thus, a given mass of silver in nanoparticle form can lead to more successful collisions between particles, resulting in faster reaction rates.