Question

As per law of definite peropertion carbon and oxygen conbined in the oxygen in a ratio 3:8 calculate the mass of oxygen the required to react completely with 6gm of carbon

Answer 1

First you need to convert 6g of carbon to moles, using 12g/mol atomic mass of carbon.

$6g C\times\frac{1mol}{12g} = 0.5 mol C$

Since the elements react in the ratio 3:8 we find how much oxygen reacts with 0.5 mol C

$0.5 mol C\times\frac{8mol O_2}{3molC}= 1.333mol of O_2$

Then we use the number of moles and the molecular mass of oxygen 16g/mol to calculate mass of oxygen.

$1.33mol O_2\times\frac{32g}{mol}= 42.7g of oxygen$.