Question

What is the mass of H2O obtained when 30g of C2H6 completely reacts with 500 g of O2 (C=12, H=1, O=16)?

options
a) 36.6g b)6g c)54g d) 18g

Answer 1

The balanced equation is `2C_2H_6 + 7O_2 -> 4CO_2 + 6H_2O`

Molar mass of
`C_2H_6 -> 30g`
`O_2->32g`
`CO_2->44g`
`H_2O->18g`

2 moles of `C_2H_6` is `30*2=60g`
7 moles of `O_2` is `32*7=224g`
produces,
4 moles of `CO_2` is `44*4=176g`
6 moles of `H_2O` is `18*6=108g`.

So according to the question, `30g` of `C_2H_6` should be reacting with `112g` of `O_2` to produce, `88g` of `CO_2` and `54g` of `H_2O`.

p.s . `500-112=388g` of `O_2` remains unreacted as `C_2H_6` is a limiting reagent and gets over before `O_2`.