Question

using the equation 2H2+O2-->2H2O if 19g of oxygen reacts completely, how many grams of hydrogen must react with it

Answer 1

Answer: 2.4 grams

Explanation:

To calculate the moles, we use the equation:

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

For $O_2$

Given mass = 19 g

Molar mass of  $O_2$ = 32 g/mol

Putting values in above equation, we get:

$\text{Moles of}O_2=\frac{19}{32}=0.60moles$

$2H_2+O_2\rightarrow 2H_2O$

1 mole of $O_2$ reacts with 2 moles of $H_2$

0.60 moles of $O_2$ wil react with =$\frac{2}{1}\times 0.60=1.20$ moles of $H_2$

mass of $H_2=moles\times {\text {molar mass}}=1.20moles\times 2g/mol=2.4g$

Thus 2.4 grams of hydrogen will react completely with 19 g of oxygen.

Answer 2

Hello!

For this reaction: 2H₂ + O₂ → 2H₂O

If 19 g of oxygen reacts completely, you'll need 2,39 g of H₂

To calculate that, you need to use the following conversion factor, applying molar equivalences, reaction coefficients, and molar masses, to go from grams of Oxygen to grams of Hydrogen:

$H_{2} Mass=19g O_{2}* \frac{1 mol O_{2}}{31,9988gO_{2}}* \frac{2 mol H_{2}}{1 mol O_{2}}* \frac{2,01588 gH_{2}}{1 mol H_{2}} =2,39gH_{2}$