Question

10g of hydrogen and 64g of oxygen were filled in a steel vessel and exploded. Amount of water produced in this reaction will be......?(a)2 mol (b)3 mol (c)4 mol (d)1 mol

Answer 1

first we see reaction by which form water
2H2+ O2--->2H2O
here we see 2mole hydrogen react with 1mole Oxygen form two mole water

we have
10gm hydrogen =5mole hydrogen
64gm Oxygen =2mol mole oxygen

we know according to above reaction
4gm hydrogen react with 32gm oxygen
so,
10gm hydrogen react with 80gm oxygen
but we have given amount of oxygen only 64 gm it means Oxygen is here limiting reagent .
now
all oxygen reat then 8gm hydrogen react and form 4mole of water .
hence option(c) is correct

Answer 2

The required equation is :-

2H2+ O2------2H20

2. :1. : 2(molar ratio)

This implies that 2 moles of hydrogen requires 1 mole of oxygen to obtain 2 moles of water .

Here v have 10 g of H2 which is = 5 moles

So v need 2.5 moles of O2 according to the molar ratio

2.5 moles of O2= 80 g

But v just have 64 g of O2(2 moles) that means O2 is the limiting reagent.

This implies 2 moles will O2 will form 4 moles of water.