Elements are made of atoms - AQA - GCSE Chemistry - Question 1 - 2017 - Paper 1
Question 1
Elements are made of atoms.
Table 1 shows the atomic numbers and mass numbers of three atoms.
Table 1
Atom Atomic number Mass number
1 12 24
2 ... show full transcript
Worked Solution & Example Answer:Elements are made of atoms - AQA - GCSE Chemistry - Question 1 - 2017 - Paper 1
Step 1
Suggest, in terms of the number of subatomic particles, why the atomic numbers of the three atoms are the same.
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Answer
The atomic numbers are the same because all three atoms have the same number of protons; specifically, they each have 12 protons.
Step 2
Explain, in terms of the number of subatomic particles, why the mass numbers of the three atoms are different.
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Answer
The mass number varies because it is the sum of protons and neutrons. Since all three atoms have 12 protons, the difference in mass numbers indicates different quantities of neutrons. For example, the first atom has 12 neutrons (mass number 24), the second has 13 neutrons (mass number 25), and the third has 14 neutrons (mass number 26).
Step 3
How many elements are in the formula H₂SO₄?
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The formula H₂SO₄ contains three different elements: hydrogen (H), sulfur (S), and oxygen (O).
Step 4
How many atoms are in the formula H₂SO₄?
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The total number of atoms in H₂SO₄ is 7. This comes from 2 hydrogen atoms, 1 sulfur atom, and 4 oxygen atoms (2 + 1 + 4 = 7).
Step 5
What is the mass of the products?
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Answer
The mass of the products is 319 g, which is the sum of the mass of copper sulfate (CuSO₄) and the mass of water (H₂O) produced.
Step 6
Describe and explain the changes seen during the reaction.
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Answer
During the reaction of sulfuric acid with copper carbonate, several observable changes occur. The solution initially is clear, but as the reaction proceeds, the solution may turn blue due to the formation of copper sulfate. The mass of the solution decreases as gas is released and solid carbonate disappears, leading to effervescence. Furthermore, the limewater turns milky due to the formation of calcium carbonate when carbon dioxide is produced.
