Chlorine is used by textile manufacturers to bleach cloth. excess chlorine is destroyed by its reaction with sodium thiosulfate, na2s2o3, as follows:
na2s2o3(aq) + 4cl2( g) + 5h2o right-arrow 2nahso4(aq) + 8hcl(aq)
1)how many moles of hcl can form from 0.21 mol of cl2?
2)how many moles of h2o are required for the reaction of 0.18 mol of cl2?
3)how many moles of h2o react if 0.50 mol hcl is formed?

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.)