How many moles of sodium chloride are present in 22.0mL of 0.500M solution?

Answer 1

To answer any question structured like this.

recognise that "0.500M" means moles per liter (mol.l-1) so in this case we have 0.500 moles in a liter of water.

We need to convert the two units of volume used (ml and l) into the same unit. There are 1000ml in 1l, so we should divide the concentration (mol.l-1) by 1000 to work in ml (reciprocal liters here remember), or divide the volume (22 ml) by 1000 to work in liters. In this case I will divide the concentration, because the question asks for the answer in millilitres.

The concentration is now written as 0.0005 mol.ml-1. Since we have several decimal places we will use standard form 5x10-4 mol.ml-1.

As you can see, if you multiply the concentration (mol.ml-1) by the number of milliliters we have, the ml and ml-1 cancel to leave us with the number of moles, the answer. In this case 22 ml * 5x10-4 mol.ml-1 = 0.011 moles of sodium chloride in 22 ml of 0.500M solution

Answer 2

To calculate the moles of sodium chloride in the solution, we need to use the formula:

moles = molarity (M) * volume (L)

moles = 0.500 mol/L * 0.022 L

moles = 0.011 mol

Therefore, there are 0.011 moles of sodium chloride in 22.0 mL of a 0.500M solution.