This question is about oxides - AQA - A-Level Chemistry - Question 2 - 2020 - Paper 3
Question 2
This question is about oxides.
Sodium oxide forms a solution with a higher pH than magnesium oxide when equal amounts, in moles, of each oxide are added separately ... show full transcript
Worked Solution & Example Answer:This question is about oxides - AQA - A-Level Chemistry - Question 2 - 2020 - Paper 3
Step 1
State why both oxides form alkaline solutions.
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Answer
Both sodium oxide and magnesium oxide react with water to produce hydroxide ions, which results in an alkaline solution. This is due to the dissolution of metal hydroxides that contribute to the increase in hydroxide ion concentration in the solution.
Step 2
Suggest why sodium oxide forms a solution with a higher pH than the solution formed from magnesium oxide.
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Answer
Sodium hydroxide is more soluble in water than magnesium hydroxide. Therefore, when sodium oxide dissolves, it produces more hydroxide ions, leading to a higher pH compared to the solution formed from magnesium oxide.
Step 3
Give an equation for the reaction between phosphorus(V) oxide and water.
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Answer
P_4O_{10} + 6H_2O
ightarrow 4H_3PO_4
Step 4
Give two equations to show how the vanadium(V) oxide acts as a catalyst in this process.
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