Question

How many molecules are in 30 liters of methane (CH4) at STP?

Answer 1

Hello!

How many molecules are in 30 liters of methane (CH4) at STP ?

We have the following information:

Knowing that by Avogadro's Law for each mole of substance we have 6.02 * 10²³ molecules, it is known that in STP (Standard Temperature and Pressure) one mole of any gas equals 22.4 L, then:

22.4 L ----------------- 6.02*10²³ molecules

30 L -------------------- y molecules

$\dfrac{22.4}{30} = \dfrac{6.02*10^{23}}{y}$

multiply the means by the extremes

$22.4*y = 30*6.02*10^{23}$

$22.4*y = 1.806*10^{25}$

$y = \dfrac{1.806*10^{25}}{22.4}$

$\boxed{\boxed{y = 8.0625*10^{23}\:molecules}}\:\:\:\:\:\:\bf\green{\checkmark}$

Answer:

8.0625*10²³ molecules of methane

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Answer 2

Number of molecules are 8.07*10²³ molecules.

Given - Volume of methane

Find - Number of molecules

Solution - As per the known fact, 1 mole of any gas occupied 22.4 litres at STP. Also, we know that 1 mole contains Avogadro's number of constituent units like atoms, molecules or ions. Hence, 22.4 litre of methane at STP will contain 6.022*10²³ molecules.

So, using this relation to find the number of molecules in volume of methane.

Number of molecules = 6.022*10²³*30/22.4

Number of molecules = 8.07*10²³

Hence, 8.07*10²³ molecules are in 30 liters of methane (CH4) at STP.

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