Question

How many molecules are in 2L of water vapor at STP?

Answer 1

Answer:

5.4 x 10²²molecules

Explanation:

Given parameters = 2L

Unknown; number of molecules

Condition of the water vapor is at standard Temperature and Pressure

Solution

To solve this problem, we simply find the number of moles the given volume would yield at STP using the relationship below:

             Number of moles = $\frac{volume occupied}{22.4}$

    Number of moles = $\frac{2}{22.4}$ = 0.089mole

To find the number of molecules in the solved mole of the water vapor:

we use the avogadro's constant to evaluate.

             1 mole of a water vapor = 6.02 x 10²³ molecules

             0.089 mole of water vapor =  0.54 x 10²³molecules

Number of molecules of water is 5.4 x 10²²molecules