In recent years the concentration of co2 in the atmosphere has increased to approximately 350 ppm based on mass content. given the approximate composition of air: o2 – 20.36% wt co2 – 0.035% wt n2 – 76.595% wt ar – 0.01% wt h2o – 3.0% wt a) determine the average molecular weight of air. b) determine the composition of air in mol %. c) determine the ppm of co2 based on mole content.

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.)