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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 look for a particle where the number of electrons exceeds the number of protons. In the provided data:
- Particle W has 9 electrons and 9 protons (neutral).
- Particle X has 10 electrons and 12 protons (positive, because 10 < 12).
- Particle Y has 16 electrons and 16 protons (neutral).
- Particle Z has 18 electrons and 16 protons (negative, because 18 > 16).
Therefore, particle Z is the negative ion.
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 identify the composition of the compound:
- Calcium (Ca): 1 atom × 40 = 40
- Nitrogen (N): 2 atoms × 14 = 28
- Oxygen (O): 6 atoms × 16 = 96
Now, we sum these values:
Thus, the relative formula mass of calcium nitrate, Ca(NO3)2, is 164.