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AQA GCSE · Question 04.3 · Quantitative chemistry
Rings can be made from 22 carat gold. The ratio of the mass of gold in 22 carat gold compared to 9 carat gold is 22 : 9.
Calculate the mass of gold in a 22 carat gold ring of mass 5.0 g. Use Table 3.
Rings can be made from 22 carat gold. The ratio of the mass of gold in 22 carat gold compared to 9 carat gold is 22 : 9.
Calculate the mass of gold in a 22 carat gold ring of mass 5.0 g. Use Table 3.
How to approach this question
1. Find the mass of gold in the 9 carat ring of mass 5.0 g from Table 3 (it is 1.9 g).
2. Set up a proportion using the given ratio: (Mass in 22 carat ring) / (Mass in 9 carat ring) = 22 / 9.
3. Rearrange the equation to solve for the mass in the 22 carat ring.
4. Substitute the known mass of gold in the 9 carat ring (1.9 g) and calculate the result.
Full Answer
Mass of gold in 9 carat ring = 1.9 g
Ratio: (mass in 22 carat) / (mass in 9 carat) = 22 / 9
Mass in 22 carat = (22 / 9) × mass in 9 carat
Mass in 22 carat = (22 / 9) × 1.9 g
Mass in 22 carat = 4.644... g
Answer: 4.6 g
The question states the ratio of gold mass in a 22 carat piece to a 9 carat piece of the same total mass is 22:9.
From Table 3, we know a 5.0 g, 9 carat ring contains 1.9 g of gold.
Let 'x' be the mass of gold in a 5.0 g, 22 carat ring.
We can set up a proportion:
x / 1.9 g = 22 / 9
To find x, we multiply both sides by 1.9:
x = (22 / 9) × 1.9
x = 2.444... × 1.9
x = 4.644... g
Rounding to two significant figures gives 4.6 g.
Common mistakes
✗ Using the total mass of the ring (5.0 g) instead of the mass of gold (1.9 g) in the calculation.
✗ Inverting the ratio (9/22).
✗ Calculation errors.
Practice the full AQA GCSE Chemistry Foundation Tier Paper 2
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