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The formula of an aluminium ion is Al$^{3+}$ - Edexcel - GCSE Chemistry - Question 2 - 2017 - Paper 1
Question 2
The formula of an aluminium ion is Al$^{3+}$. The formula of a sulfate ion is SO$_4^{2-}$. (i) Which of the following is the correct formula of aluminium sulfate?... show full transcript
Worked Solution & Example Answer:The formula of an aluminium ion is Al$^{3+}$ - Edexcel - GCSE Chemistry - Question 2 - 2017 - Paper 1
Step 1
Step 2
To test for the presence of sulfate ions in a solid, the solid is first dissolved in water and then two solutions are added.
Answer
The two solutions that are commonly added to test for sulfate ions are:
- Barium chloride (BaCl)
- Hydrochloric acid (HCl) When barium chloride is added to a solution containing sulfate ions, a white precipitate of barium sulfate (BaSO) forms.
Step 3
Step 4
Describe, in terms of their electronic configurations, how calcium and oxygen atoms react to form calcium and oxide ions.
Answer
Calcium (Ca) has an electronic configuration of 2.8.2 and loses 2 electrons to achieve a stable octet, forming Ca ions with an electronic configuration of 2.8. Oxygen (O) has an electronic configuration of 2.6 and gains 2 electrons to complete its outer shell, forming O ions with an electronic configuration of 2.8. The resulting ionic compound, CaO, forms through the electrostatic attraction between the Ca and O ions.