Photo AI
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
-
Higher Relative Strength: Kevlar ® has a relative strength of 5 compared to steel's relative strength of 1. This means Kevlar ® can withstand greater forces without failing, making it more effective for protective applications such as body armour.
-
Flexibility: Kevlar ® is characterized by high flexibility, allowing it to be comfortable when worn. In contrast, steel is low in flexibility and could be restrictive and heavier, making it less suitable for body armour.
Step 2
Calculate the surface area to volume ratio of this cube of silver.
Answer
To calculate the surface area and volume of the cube, use the following formulas:
- Surface Area (SA) = 6 × side²
- Volume (V) = side³
For a cube with a side length of 2 cm:
- SA = 6 × (2 cm)² = 6 × 4 cm² = 24 cm²
- V = (2 cm)³ = 8 cm³
Now, calculate the surface area to volume ratio:
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 have a significantly larger surface area compared to the same mass of material in powder form. This increased surface area allows more atoms to be available for reaction, which leads to a higher reaction rate. Additionally, nanoparticles can provide unique properties such as improved dispersion and the ability to enhance catalytic activity due to their quantum effects. As a result, using silver as nanoparticles makes it more effective as a catalyst by increasing the likelihood of interactions with reactants.