In the extraction of aluminium from bauxite ore, several steps are involved. in one of these, sodium hydroxide (naoh) reacts with aluminium oxide (al2o3) to produce sodium aluminate (naalo2) and water. write down a balanced chemical equation showing this reaction. explain how you can test that your equation is balanced.

Modern pennies are composed of zinc coated with copper. a student determines the mass of a penny to be 2.482 g and then makes several scratches in the copper coaling (to expose the underlying zinc). the student puts the scratched penny in hydrochloric acid, where the following reaction occurs between the zinc and the hcl (the copper remains undissolved): zn(s) + 2 hcl(aq) → h2(g) + zncl(aq)the student collects the hydrogen produced over water at 25 °c. the collected gas occupies a volume of 0.899 l at a total pressure of 79 j mmhg. calculate the percent zinc (by mass) in the penny. (assume that all the zn in the penny dissolves.)

The valence of aluminum is +3, and the valence of the chlorine is -1. the formula fir the aluminum chloride is correctly written as

How does a large body of water, such as the ocean, influence climate?