How to find the amount in mol

Ca atoms in 60.0 grams calcium
NH3 molecules in 22g of ammonia
H2O molecules in 20.0g of CuSO4.5H20
Cl- ions in 34g of FeCl3

To find the number of moles of any substance, we use the formula: n = m/m.m, where n is the number of moles, m is the mass being measured, and m.m is the molar mass of the substance.

1) Ca has m.m of 40.08g

n = m/m.m
= 60/40.08
n = 1.497 mol (4sf)

2) NH3 has m.m of 17.034g

n = m/m.m
= 22/17.034
= 1.292 mol (4sf)

3) H2O has m.m of 18.016g
CuSO4.5H2O has m.m of 249.69g

n(CuSO4.5H2O) = m/m.m
= 20/249.69
= 0.0801 mol (4sf)

m(H2O) = n x m.m
= 0.0801 x 18.016
= 1.443g (exact)

4) FeCl3 has m.m of 162.2g
Cl3 has m.m of 106.35g

n(FeCl3) = m/m.m
= 34/162.2
= 0.2096 (4sf)

m(Cl3) = 0.2096 x 106.35
= 22.29g (exact)

Yes my answers to 3) and 4) are wrong. Sorry about that!

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Mass of substance/its molecular mass