AP Problem of the Day

In part (i), coefficients should be in terms of lowest whole numbers. Assume that solutions are aqueous unless otherwise indicated. Represent substances in solutions as ions if the substances are extensively ionized. Omit formulas for any ions or molecules that are unchanged by the reaction.

1) Magnesium metal is strongly heated in oxygen gas.
(i) Balanced equation:

(ii) What is the oxidation number of magnesium before the reaction occurs, and what is the oxidation
number of magnesium after the reaction is complete?
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2) A solution of nickel(II) chloride is added to a solution of sodium hydroxide, forming a precipitate.
(i) Balanced equation:

(ii) If equal volumes of 1.0 M nickel(II) chloride and 1.0 M sodium hydroxide are used, what ion is
present in the solution in the highest concentration after the precipitate forms?