chemistry: solve (or indicate) for the equivalent weight of each ff. substances:?

Question

a) potassium hydroxide
b)sulfuric acid
c) silver nitrate
d) ammonium carbonate
e) ferric chloride
f) phosphoric acid
g) nitric acid
h) barium chloride
i)sodium hydroxide

Answer 1

I am not going to do the calculations. I'll just write the equivqlent weight (EW) with respect to the molecular weight (MW)

EW=MW/n where n is the number of equivalents per molecule.
For acids n is the number of H+ per molecule,for bases the number of OH-, for ions the charges, for oxidants/reductants the number of e gained or lost.

a) KOH base with 1 OH- ->EW=MW/1=MW
b) H2SO4 acid with 2 H+ -> EW= MW/2
c) AgNO3 salt. Look only at the cation. Ag+ ->charge +1, so EW=Mw/1=MW
d) (NH4)2CO3. Salt. NH4+ has 1 charge but you have 2 of them per molecule, thus you have n=1*2=2 and EW=MW/2
e) FeCl3 salt, Fe+3 -> EW=MW/3
f) H3PO4 acid with 3H+ -> EW=MW/3
g) HNO3. Now this is tricky. Usually you would treat is as acid with 1 H+, thus EW=MW/1. However HNO3 can act as an oxidant. Depending on the conditions it might gain 2 electrons and form NO2 (then EW=MW/2) or it might gain 4 e and form NO (then EW=MW/4)
h) BaCl2,salt, Ba+2 -> EW=MW/2
i) NaOH base 1OH- -> EW=MW/1=MW

Note that for the salts I chose the cation. That means that we find the equivalent weight for positive charges. You could have done the same using the anion and you would reach the same result (salts contain the same number of positive and negative charges). Choosing the anion or cation to determine the EW depends on the reaction. You choose the ion that is involved in the reaction you are interested in.