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2 (a) Salts of metals can be prepared by reacting the metal with an acid to produce the salt and hydrogen - Edexcel - GCSE Chemistry - Question 2 - 2018 - Paper 1
Question 2
2 (a) Salts of metals can be prepared by reacting the metal with an acid to produce the salt and hydrogen. i) Describe the test to show the gas is hydrogen. ii) Ni... show full transcript
Worked Solution & Example Answer:2 (a) Salts of metals can be prepared by reacting the metal with an acid to produce the salt and hydrogen - Edexcel - GCSE Chemistry - Question 2 - 2018 - Paper 1
Step 1
Describe the test to show the gas is hydrogen.
Answer
To test for hydrogen gas, carry out the following steps:
- Take a lit splint.
- Bring the lit splint close to the mouth of the test tube where the gas is being collected.
- If hydrogen is present, it will combust with a 'pop' sound, signaling that the gas is hydrogen.
Step 2
Explain how the structure of a nickel atom, Ni, changes when it forms a nickel ion, Ni²⁺.
Answer
When a nickel atom (Ni) forms a nickel ion (Ni²⁺), it undergoes a loss of two electrons. The atomic structure changes as follows:
- Nickel has an atomic number of 28, which indicates it has 28 protons and, in a neutral state, also 28 electrons.
- When it loses two electrons to form Ni²⁺, the new electron configuration becomes similar to that of argon, having only 26 electrons.
- This loss results in a positively charged ion, affecting its chemical properties and reactivity.
Step 3
Calculate the concentration of the solution in g dm⁻³.
Answer
To calculate the concentration of the solution in g dm⁻³, follow these steps:
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The mass of nickel sulfate used is 23.5 g.
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The volume of the solution is 250 cm³, which can be converted to dm³:
250 cm³ = 0.25 dm³.
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The concentration can be calculated using the formula:
C = rac{mass (g)}{volume (dm³)} = rac{23.5 g}{0.25 dm³} = 94 g dm⁻³.
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Therefore, the concentration of the nickel sulfate solution is 94 g dm⁻³.