This question is about the metal gold - Edexcel - GCSE Chemistry - Question 7 - 2021 - Paper 1
Question 7
This question is about the metal gold.
(i) Gold can be hammered into shape.
State the name of this property.
(ii) Gold alloys can be used to repair teeth.
One reaso... show full transcript
Worked Solution & Example Answer:This question is about the metal gold - Edexcel - GCSE Chemistry - Question 7 - 2021 - Paper 1
Step 1
State the name of this property.
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Answer
The property of gold that allows it to be hammered into shape is known as malleability.
Step 2
Give one other reason why gold alloys are used to repair teeth.
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Answer
Gold alloys are used in dental applications because they are non-reactive and do not corrode in the mouth.
Step 3
Calculate the mass of gold in 2.00 kg of this alloy.
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Answer
To find the mass of gold in a gold alloy that contains 78% gold by mass, first convert 2.00 kg to grams: 2.00 kg = 2000 g.
Next, calculate the mass of gold:
ext{Mass of gold} = 2000 ext{ g} imes rac{78}{100} = 1560 ext{ g}
Step 4
Draw one straight line from each hazard symbol to its meaning.
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Answer
Corrosive - (hazard symbol for corrosive)
Flammable - (hazard symbol for flammable)
Hazardous to the environment - (hazard symbol for hazardous to the environment)
Oxidising - (hazard symbol for oxidising)
Step 5
Explain the observations and give reasons why the masses after heating are less than expected.
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Answer
The observations can be explained by the loss of mass due to the reaction of copper with oxygen. When heating the copper, some of it reacts to form copper oxide, resulting in a mass increase in one container, while the other contains unreacted copper. However, if there is insufficient oxygen or the copper is not fully oxidized, the expected increase in mass may not occur. This accounts for the masses being less than expected, possibly due to the loss of gases during the reaction.
