Q5 — Conservation of mass (5 marks)

A student burns 2.4 g of magnesium ribbon in a crucible with a loose lid. After heating, the white solid weighs 4.0 g.

(a) Write a balanced symbol equation, with state symbols, for the reaction. (2) (b) Explain, with reference to the law of conservation of mass, why the product weighs more than the original ribbon. (2) (c) State one reason why the measured product mass might be less than the true theoretical mass. (1)