Question

How many molecules are there in 15.7 liters of chlorine gas at STP?

Answer 1

 As we know that
 At STP
1 mole of any gas occupies 22.4L 
so
15.7L / 22.4L/mole = 0.7moles Cl2 
0.7moles x 6.022x10^23molecules/mole = 4.22x10^23molecules
hope it helps

Answer 2

Hello!

How many molecules are there in 15.7 liters of chlorine gas at STP?

We have the following information:

Knowing that 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

15.7 L ----------------- y molecules

$\dfrac{22.4}{15.7} = \dfrac{6.02*10^{23}}{y}$

$22.4*y = 15.7*6.02*10^{23}$

$22.4\:y = 9.4514*10^{24}$

$y = 4.219375*10^{23}\:\to\:\boxed{\boxed{y \approx 4.22*10^{23}\:molecules}}\end{array}}\qquad\checkmark$

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I Hope this helps, greetings ... Dexteright02! =)