Chemistry – Atoms, elements and compounds - Elements, compounds and mixtures | e-Consult

The student can distinguish between copper sulfate (a compound) and pure copper (an element) by observing their chemical properties. Copper sulfate is a compound formed from copper and sulfate ions. Pure copper is an element and is characterized by its metallic properties.

Here's a procedure the student could follow:

1. Reaction with dilute acid: Copper sulfate will react with dilute acid (e.g., hydrochloric acid, HCl) to produce a blue solution and copper ions. The reaction is: CuSO₄(aq) + 2HCl(aq) → CuCl₂(aq) + H₂SO₄(aq). Pure copper will not react with dilute acid. If the student adds dilute acid to the copper, nothing will happen.
2. Electrical Conductivity: Copper is an excellent conductor of electricity, while copper sulfate in solution is not. The electrical conductivity test will clearly differentiate between the two. A wire of pure copper will conduct electricity, while a solution of copper sulfate will not.
3. Colour: Copper sulfate is a blue solid, while pure copper is a reddish-brown solid. This is a simple visual distinction.

Therefore, the student can conclude that the blue, reactive substance is copper sulfate, and the reddish-brown, non-reactive substance is pure copper.