making salts exam questions Flashcards
(12 cards)
Why is excess copper carbonate or copper(II) oxide added during the salt-making practical?
To ensure all the acid is neutralised and no acid remains.
How do you separate the unreacted base from the salt solution?
By filtration using filter paper and a funnel.
Why is the salt solution heated after filtration?
To evaporate water and allow the salt to crystallise.
Why is a water bath sometimes used instead of direct heating?
To gently heat the solution and reduce the risk of splashing or boiling over.
Write the balanced symbol equation for the reaction between copper(II) oxide and sulfuric acid.
H₂SO₄(aq) + CuO(s) → CuSO₄(aq) + H₂O(l)
What salt is formed when copper(II) oxide reacts with sulfuric acid?
Copper(II) sulfate.
Describe how to make a pure, dry sample of copper sulfate from copper(II) oxide and sulfuric acid.
Add excess CuO to warm H₂SO₄, filter to remove excess, evaporate water, let crystals form, then dry them.
Why is the mixture heated until the mass does not change?
To ensure all the water has evaporated, leaving only dry salt.
How does a student calculate the mass of salt after heating?
Subtract the mass of the empty evaporating dish from the mass of the dish with dry salt.
What is observed when copper(II) oxide is added to sulfuric acid?
The black solid disappears and a blue solution forms until no more reacts.
