Unit 6 Test Review CP

When  $Co_3O_4$  is heated with hydrogen, cobalt metal can be formed. How does this equation show that  $Co_3O_4$   is reduced? 

• it loses oxygen

• it gains oxygen

• oxygen does not change

• oxygen is doubled

Potassium manganate(VII) is produced from manganese(IV) oxide by an oxidation reaction. What is meant by the term oxidation?

• losing oxygen

• gaining oxygen

• oxygen being present

• oxygen staying the same

Nickel can be obtained from nickel(II) oxide by heating it with a mixture of carbon monoxide and hydrogen. How does this equation show that the nickel(II) oxide is reduced?

• it gains oxygen

• it has oxygen present

• oxygen remains the same

• it loses oxygen

The equations shown are all redox reactions. Which oxide is oxidized in these reactions?

• $Fe_2O_3$

• CO

• ZnO

• NO

Iron from a blast furnace contains carbon, sulfur, silicon and phosphorus as impurities. Iron is converted into steel in a basic oxygen converter. The impurities undergo oxidation. What is meant by the term oxidation?

• oxygen tripled

• lose of oxygen

• gain of oxygen

• oxygen remains the same

Magnesium cannot be produced by electrolysis of aqueous magnesium chloride using inert electrodes. Name the product formed at the negative electrode (cathode) during the electrolysis of aqueous magnesium chloride.

• magnesium

• chlorine

• oxygen

• hydrogen

Magnesium cannot be produced by electrolysis of aqueous magnesium chloride using inert electrodes. Suggest how magnesium can be produced from magnesium chloride by electrolysis.

• Make it solid before electrolysis

• Make molten before electrolysis

• Add more water to aqueous solution before electrolysis

• Switch the chloride for bromine before electolysis

Predict the product of the electrolysis of molten zinc iodide at the negative electrode.

• zinc

• iodine

• hydrogen

• oxygen

Predict the product of the electrolysis of molten zinc iodide at the positive electrode.

• zinc

• iodine

• hydrogen

• oxygen

Magnesium is manufactured by the electrolysis of molten magnesium chloride. What information in the diagram shows that molten magnesium is less dense than molten magnesium chloride?

• magnesium sank under the molten magnesium chloride

• magnesium floats on the molten magnesium chloride

• the magnesium and molten magnesium chloride mix

• the diagram does not give enough information