Question

How many molecules are there in 31.8 moles of water?

Answer 1

Answer:

$31.8\ moles = 1.91 * 10^{25}\ molecules$

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:

$31.8\ moles = 1.91 * 10^{25}\ molecules$