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Ionic compounds contain ions - Edexcel - GCSE Chemistry Combined Science - Question 3 - 2016 - Paper 1
Question 3
Ionic compounds contain ions. (a) The numbers of electrons, neutrons and protons in four particles, W, X, Y and Z, are shown in Figure 5. Explain which particle, W... show full transcript
Worked Solution & Example Answer:Ionic compounds contain ions - Edexcel - GCSE Chemistry Combined Science - Question 3 - 2016 - Paper 1
Step 1
Explain which particle, W, X, Y or Z, is a negative ion.
Answer
To determine which particle is a negative ion, we need to compare the number of electrons and protons for each particle. A negative ion has more electrons than protons. Reviewing the provided data:
- W: 9 electrons, 9 protons → Neutral
- X: 10 electrons, 12 protons → Neutral
- Y: 16 electrons, 16 protons → Neutral
- Z: 18 electrons, 18 protons → Neutral
None of the particles provided data indicating an excess of electrons compared to protons. Therefore, no particle is a negative ion based on the data presented.
Step 2
Calculate the relative formula mass of calcium nitrate, Ca(NO₃)₂.
Answer
To calculate the relative formula mass of calcium nitrate, we first need to find the contributions of each element in the formula:
- Calcium (Ca): The atomic mass is 40.
- Nitrogen (N): The atomic mass is 14 and there are 2 nitrogen atoms in Ca(NO₃)₂.
- Oxygen (O): The atomic mass is 16 and there are 6 oxygen atoms (3 for each nitrate ion, and 2 nitrate ions).
Now, we can calculate the total mass:
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Total mass of Calcium:
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Total mass of Nitrogen:
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Total mass of Oxygen:
Adding these together gives:
Thus, the relative formula mass of calcium nitrate, Ca(NO₃)₂, is 164.