Question

Vanadium (V) and oxygen (O) can combine to form several different compounds. The composition of two of them are:

Compound I: 1.112 g of O for every 3.541 g of V

Compound II: 3.326 g of O for every 4.236 g of V

If compound I is VO, then compound II is:

the answer is V2O5

how?!

Answer 1

COMPOUND 1:

we have mass of each elements as:

V: 3.54 g

O: 1.11 g

Divide by molar mass to get number of moles of each:

V: 3.54/50.94 = 0.07

O: 1.11/16.0 = 0.07

Divide by smallest to get simplest whole number ratio:

V: 0.07/0.07 = 1

O: 0.07/0.07 = 1

So formula is:

VO

COMPOUND 2:

we have mass of each elements as:

V: 4.24 g

O: 3.33 g

Divide by molar mass to get number of moles of each:

V: 4.24/50.94 = 0.08

O: 3.33/16.0 = 0.21

Divide by smallest to get simplest whole number ratio:

V: 0.08/0.08 = 1

O: 0.21/0.08 = 2.5

multiply by 2 to get whole number:

V : 1*2 = 2

O : 2.5*2 = 5

So formula is:

V2O5