What is the mass of 3.1*1022 molecules of NaCl?

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.)

Which of the following is the correct formula for copper (i) sulfate trihydrate? cuso4 · 3h2o cuso4(h2o)3 cu2so4(h2o)3 cu2so4 · 3h2o

The plant food contains nh4)3po4 what tests would you run to verify the presence of the nh4 ion and the po4 ion