Adrinking water at ph 7.2 contains 8 x 10^-4 m tot ca and has an alkalinity of 80 mg/l as caco3, provided entirely by species of the carbonate group. it is desired to adjust the ph of this water to cause calcite to be slightly supersaturated for the purposes of corrosion control. how much lime must be added to achieve a saturation index of 0.2? what would the ph of the water be?

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.)