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The thermal decomposition of potassium chlorate can be used to produce oxygen in the laboratory. 2KClO3 (s) → 2KCl (s) + 3O2 (g) What volume (L) of O2 gas at 25 °C and 1.00 atm pressure is produced by the decomposition of 7.5 g of KClO3 (s)?

Answer :

Answer : The volume of [tex]O_2[/tex] gas produced is 2.24 L

Explanation :

First we have to calculate the moles of [tex]KClO_3[/tex].

[tex]\text{Moles of }KClO_3=\frac{\text{Mass of }KClO_3}{\text{Molar mass of }KClO_3}[/tex]

Molar mass of [tex]KClO_3[/tex] = 122.55 g/mole

[tex]\text{Moles of }KClO_3=\frac{7.5g}{122.55g/mole}=0.06119mole[/tex]

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

The balanced chemical reaction is:

[tex]2KClO_3(s)\rightarrow 2KCl(s)+3O_2(g)[/tex]

From the reaction we conclude that,

As, 2 moles of [tex]KClO_3[/tex] decomposes to give 3 moles of [tex]O_2[/tex]

So, 0.06119 moles of [tex]KClO_3[/tex] decomposes to give [tex]\frac{0.06119}{2}\times 3=0.0918[/tex] moles of [tex]O_2[/tex]

Now we have to calculate the volume of [tex]O_2[/tex] gas.

Using ideal gas equation :

[tex]PV=nRT[/tex]

where,

P = Pressure of [tex]O_2[/tex] gas = 1.00 atm

V = Volume of [tex]O_2[/tex] gas = ?

n = number of moles  [tex]O_2[/tex] = 0.0918 mole

R = Gas constant = [tex]0.0821L.atm/mol.K[/tex]

T = Temperature of [tex]O_2[/tex] gas = [tex]25^oC=273+25=298K[/tex]

Putting values in above equation, we get:

[tex]1.00atm\times V=0.0918mole\times (0.0821L.atm/mol.K)\times 298K[/tex]

[tex]V=2.24L[/tex]

Therefore, the volume of [tex]O_2[/tex] gas produced is 2.24 L

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