contestada

2H2 +O2 → 2H2O

What mass of water forms when 1.45 × 10-3 g O2 react completely? (Molar mass of O2 = 32.00 g/mol; molar mass of H2O = 18.02 g/mol)

1.63 × 10-3 g

8.16 × 10-4 g

1.29 × 10-3 g

Respuesta :

1.63 x 10 ^3 g is the correct answer 

Answer : The correct option is, [tex]1.63\times 10^{-3}g[/tex]

Explanation : Given,

Mass of oxygen gas = [tex]1.45\times 10^{-3}g[/tex]

Molar mass of oxygen gas = 32 g/mole

Molar mass of water = 18.02 g/mole

First we have to calculate the moles of [tex]O_2[/tex].

[tex]\text{Moles of }O_2=\frac{\text{Mass of }O_2}{\text{Molar mass of }O_2}=\frac{1.45\times 10^{-3}g}{32g/mole}=4.53\times 10^{-5}moles[/tex]

Now we have to calculate the moles of [tex]H_2O[/tex].

The balanced chemical reaction is,

[tex]2H_2+O_2\rightarrow 2H_2O[/tex]

From the balanced reaction we conclude that

As, 1 mole of [tex]O_2[/tex] react to give 2 mole of [tex]H_2O[/tex]

So, [tex]4.53\times 10^{-5}[/tex]moles of [tex]O_2[/tex] react to give [tex]4.53\times 10^{-5}\times 2=9.06\times 10^{-5}[/tex] moles of [tex]H_2O[/tex]

Now we have to calculate the mass of [tex]H_2O[/tex]

[tex]\text{Mass of }H_2O=\text{Moles of }H_2O\times \text{Molar mass of }H_2O[/tex]

[tex]\text{Mass of }H_2O=(9.06\times 10^{-5}mole)\times (18.02g/mole)=1.63\times 10^{-3}g[/tex]

Therefore, the mass water produced is, [tex]1.63\times 10^{-3}g[/tex]