Fe3O4(s) + 4H2(g)3Fe(s) + 4H2O(g) Using standard thermodynamic data at 298K, calculate the entropy change for the surroundings when 1.79 moles of Fe3O4(s) react at standard conditions. S°surroundings = J/K

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.)

Identify the correct mole ratio for each substance. sodium chloride (nacl) na: cl = 1: ammonium nitrate (nhno) h: o = 4:

What can happen to an atoms electrons when an electric current is passed through the atom?