Question

How many molecules are there in 31.8 moles of water?

1.91 x 1025 molecules
1.91 x 1022
5.28 x 10-23 molecules
5.28x 10.25

Answer 1

`31.8\ moles = 1.91 * 10^(25)\ molecules`

Step-by-step explanation:

Given

31.8 moles of water

Required

Determine the number of molecule

In standard units: 1 molecule of water is:

`1\ mole = 6.022 * 10^(23)\ molecules`

Multiply both sides by 31.8

`31.8 * 1\ mole = 31.8 * 6.022 * 10^(23)\ molecules`

`31.8\ moles = 31.8 * 6.022 * 10^(23)\ molecules`

`31.8\ moles = 191.4996 * 10^(23)\ molecules`

Express 191.4996 as a standard form

`31.8\ moles = 1.914996 * 10^2 * 10^(23)\ molecules`

Apply law of indices:

`31.8\ moles = 1.914996 * 10^(2+23)\ molecules`

`31.8\ moles = 1.914996 * 10^(25)\ molecules`

Approximate:

`31.8\ moles = 1.91 * 10^(25)\ molecules`