Oxidation and reductionIB MYP Chemistry: Mind map

Exam questions on Oxidation and reduction

1. A student in Athens burns a strip of magnesium ribbon in air. It burns with a bright white flame and leaves a white powder of magnesium oxide, MgO, as shown by the equation 2Mg + O₂ → 2MgO. Magnesium oxide is an ionic compound made of Mg²⁺ ions and O²⁻ ions.
   Write the half-equation for magnesium atoms forming Mg²⁺ ions and explain why this is oxidation.2 marks
2. A teacher heats black copper(II) oxide, CuO, in a stream of hydrogen gas. The black solid turns into a pink-brown solid, copper, and steam is formed: CuO + H₂ → Cu + H₂O.
   Explain why this is a redox reaction, in terms of oxygen.2 marks
3. Students at a school in Manila investigate the conditions needed for iron to rust. They set up three test tubes, each containing a clean iron nail. Tube A has boiled water with a layer of oil on top. Tube B has dry air and a drying agent, calcium chloride. Tube C has tap water and is open to the air. They leave the tubes for one week.
   State a hypothesis for this investigation, with a scientific reason.3 marks