Chem question about percent yield?

Question

Many metals need to be purified after mining. One example is vanadium which is commonly found in its natural form, vanadium oxide (V2O5), when extracted from the Earth. One step in the production of pure vanadium metal uses the reaction of vanadium oxide with an excess of aluminum metal at high temperature to give pure vanadium metal and aluminum oxide. In a test run, 36.1 kg of pure vanadium metal is isolated when 76.2 kg of V2O5 reacts. Calculate the percent yield of vanadium.

Answer 1

Dont have my atomic weights handy, so here is how to do it. Find the mol weight of the pentoxide. Find the weight of 2 g-atoms of V. Form the following operation

g-atom wt of 2 V/ mole wt V2O5 x 76.2 kg.
This will give you the theoretical yield from your ore. The percent yield = 100 x 36.1/theoretical yield

Answer 2

The equation is

3V2O5 +10 Al >>5 Al2O3 +6 V

atomic mass V = 50.942 g / mol

36100 g / 50.942 = 708.6 moles V

the ratio between V2O5 and V is 3 : 6

moles V2O5 = 354

molecular mass V2O5 = 149.88 g/mol

mass V2O5 = 149.88 g/mol x 354 = 53058.9 g = 53.06 Kg

53.06 : 76.2. = x : 100

x = 69.6 %