Question

4 gms. of hydrogen are ignited with 4 gms of
oxygen. The weight of water formed is :
(1) 0.5 gm
(2) 3.5 gm
(3) 4.5 gm
(4) 2.5 gm​

Answer 1

Answer:

4.5 grams

\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}

\text{Number of moles of hydrogen}=\frac{4g}{2g/mol}=2moles

\text{Number of moles of oxygen}=\frac{4g}{32g/mol}=0.125moles

For the given balanced chemical equation:

2H_2+O_2\rightarrow 2H_2O

By Stoichiometry:

1 mole of oxygen reacts with 2 mole of hydrogen

So, 0.125 moles of oxygen react with =\frac{2}{1}\times 0.125=0.25mole of hydrogen

Oxygen is considered as a limiting reagent because it limits the formation of product.

1 mole of oxygen produce 2 moles of water.

0.125 moles of oxygen produce=\frac{2}{1}\times 0.125=0.25moles of water.

Mass of water=moles\times {\text {molar mass}}=0.25\times 18=4.5g

Answer 2

Answer:[3]

Explanation:

In this reaction O2 is limiting reagent so

Moles of O2 is 4÷32 = 1÷8

Formation moles of h2o is

2÷8=x÷18

X=4.5g

Where x is formation of water mass