Example

Let's say we have 58.5 g of Sodium Chloride (NaCl), which has a molar mass of 58.5 g/mol. The number of moles would be calculated as follows:

\( \text{Moles} = \frac{58.5 \, \text{g}}{58.5 \, \text{g/mol}} = 1.000 \, \text{mol} \)

So the number of moles of this substance would be 1.000 mol.

FAQs

How do I convert from grams to moles?

To convert from grams to moles, follow these few simple steps:

• Measure the mass of your sample in grams.
• Find the molar mass of the substance you are analyzing.
• Divide the mass by the molar mass to find the number of moles in your sample.

What is the molar mass?

The molar mass is the mass of a mole of a substance, which corresponds to the quantity of matter that contains an Avogadro's number of atoms or molecules (depending on the substance). Molar masses change widely in the periodic table: a mole of hydrogen weighs only 1.008 g, while a mole of uranium weighs 238.03 g.

How many moles are 100 grams of water?

In 100 grams of water, there are 5.551 moles. To calculate this result:

• Calculate the molar mass of water, which is two hydrogen atoms' and one oxygen atom's molar masses combined:

\( (2 \times 1.008 \, \text{g/mol}) + 15.999 \, \text{g/mol} = 18.015 \, \text{g/mol} \)

• Divide the mass of your sample by the molar mass:

\( 100 \, \text{g} / 18.015 \, \text{g/mol} = 5.551 \, \text{mol} \)

This is the number of moles in 100 g of water.

How do I calculate the molar mass?

You can find the molar mass with theoretical knowledge or experimentally.

• To roughly determine the molar mass of an unknown solid in a lab, you can use the colligative properties of solutions.
• The molar mass of a gas is straightforward to measure, as equal volumes contain an equal number of moles.
• You can calculate the molar mass of a molecule by summing the molar masses of the composing atoms with the help of the periodic table.