The chemical equation for a reaction between k2cr2o7 and hcl is shown. k2cr2o7 + 14hcl → 2crcl3 + 2kcl + 3cl2 + 7h2o
which of the following identifies the reactant that acts as an oxidizing agent in the reaction and explains the answer? 20 !

a. k2cr2o7, because the oxidation number of k changes from +6 to +3.
b. k2cr2o7, because the oxidation number of cr changes from +6 to +3.
c. hcl, because the oxidation number of h changes from −1 to 0.
d. hcl, because the oxidation number of cl changes from −1 to 0.

One way in which the useful metal copper is produced is by dissolving the mineral azurite, which contains copper(ii) carbonate, in concentrated sulfuric acid. the sulfuric acid reacts with the copper(ii) carbonate to produce a blue solution of copper(ii) sulfate. scrap iron is then added to this solution, and pure copper metal precipitates out because of the following chemical reaction: (s) (aq) (s) (aq) suppose an industrial quality-control chemist analyzes a sample from a copper processing plant in the following way. he adds powdered iron to a copper(ii) sulfate sample from the plant until no more copper will precipitate. he then washes, dries, and weighs the precipitate, and finds that it has a mass of .