This question is about metals and alloys - AQA - GCSE Chemistry - Question 3 - 2015 - Paper 2
Question 3
This question is about metals and alloys.
3(a) Explain how electricity is conducted in a metal.
To gain full marks you must include a description of the structure a... show full transcript
Worked Solution & Example Answer:This question is about metals and alloys - AQA - GCSE Chemistry - Question 3 - 2015 - Paper 2
Step 1
Explain how electricity is conducted in a metal.
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Answer
Electricity is conducted in metals due to the presence of a giant crystalline structure composed of positive ions. In this structure, there are layers of atoms which can slide over one another. The electrons in the outer shell of these metal atoms are delocalized, meaning they are not bound to any single atom. This allows them to move freely throughout the metal, leading to the flow of electric current when a voltage is applied.
Step 2
Describe how the structure of an alloy is different from the structure of a pure metal.
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Answer
An alloy consists of a mixture of different types of atoms, which can include various metals or elements. This results in a structure that has distorted layers due to the different sizes of the constituent atoms. In contrast, a pure metal has a regular arrangement of identical atoms, allowing layers to slide easily over one another.
Step 3
Why is Nitinol used in dental braces?
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Answer
Nitinol is used in dental braces because it is a shape memory alloy, which means it can return to its original shape when heated. This property allows braces to apply consistent pressure to teeth over time, facilitating their movement.
Step 4
Suggest one reason why coins are not made of pure copper.
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Answer
One reason coins are not made of pure copper is that pure copper is too soft, making it unsuitable for coins that require durability.
Step 5
Complete the sentence: Aluminium is manufactured by the electrolysis of a molten mixture of cryolite and ....
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Answer
aluminium oxide (Al₂O₃).
Step 6
How can the same reaction produce two different products?
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Answer
The same reaction can produce different products due to variations in reaction conditions, such as temperature, pressure, or the presence of different catalysts.
Step 7
Give two reasons why instrumental methods of analysis are used to detect impurities in metals.
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Answer
Instrumental methods of analysis are used to detect impurities in metals because they are accurate and sensitive, allowing for precise detection of small amounts of impurities.
