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The table shows the names and formulae of three ions - Edexcel - GCSE Chemistry - Question 6 - 2012 - Paper 1
Question 6
The table shows the names and formulae of three ions. name of ion formula of ion calcium Ca²⁺ nitrate NO₃⁻ phosphate PO₄³⁻ What is the formula of calcium nitrate? ... show full transcript
Worked Solution & Example Answer:The table shows the names and formulae of three ions - Edexcel - GCSE Chemistry - Question 6 - 2012 - Paper 1
Step 1
What is the formula of calcium nitrate?
Answer
To find the formula for calcium nitrate, we need to combine the ions calcium (Ca²⁺) and nitrate (NO₃⁻). Calcium has a +2 charge and nitrate has a -1 charge, so it will take two nitrate ions to balance the charge of one calcium ion. Therefore, the formula for calcium nitrate is:
The correct choice is B: Ca(NO₃)₂.
Step 2
The number of oxygen atoms in the formula Ca₃(PO₄)₂ is
Answer
In the formula Ca₃(PO₄)₂, we can break it down as follows:
- Each phosphate (PO₄) has 4 oxygen atoms.
- The subscript 2 outside the parentheses means there are 2 phosphate ions.
Total oxygen atoms = 2 (PO₄) * 4 (O) = 8.
Thus, the correct choice is C: 8.