What is the charge on a sulfate ion?

Study for the IGCSE Edexcel Chemistry Test. Access flashcards and multiple choice questions with hints and explanations. Get ready for your exam!

Multiple Choice

What is the charge on a sulfate ion?

Explanation:
For a polyatomic ion, the overall charge comes from summing the oxidation states of all the atoms inside it. In sulfate, there are four oxygen atoms, each with an oxidation state of -2, contributing -8 in total. The sulfur must then have an oxidation state that makes the whole ion carry a -2 charge, so sulfur is +6. Adding them up gives +6 + (-8) = -2. Therefore, the sulfate ion has a charge of -2. This means it can balance with a +2 cation, like in magnesium sulfate, where MgSO4 is formed.

For a polyatomic ion, the overall charge comes from summing the oxidation states of all the atoms inside it. In sulfate, there are four oxygen atoms, each with an oxidation state of -2, contributing -8 in total. The sulfur must then have an oxidation state that makes the whole ion carry a -2 charge, so sulfur is +6. Adding them up gives +6 + (-8) = -2. Therefore, the sulfate ion has a charge of -2. This means it can balance with a +2 cation, like in magnesium sulfate, where MgSO4 is formed.

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