The balanced chemical equation for the reaction of hydrogen and oxygen is shown below. 2H2 + O2 → 2H2O
The number of moles of hydrogen that is needed to produce 0.253 mol of water is
O smaller than 0.253 mol.
O much greater than 0.253 mol.
O slightly greater than 0.253 mol.
O equal to 0.253 mol.

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 .