Molar Mass & Mole Calculations 12/11/24

Front

What is Molar Mass?

Back

Molar mass is the mass of one mole of a substance, typically expressed in grams per mole (g/mol). It is calculated by summing the atomic masses of all atoms in a molecule.

Front

How do you calculate the number of moles from mass?

Back

To calculate the number of moles, use the formula: \( \text{moles} = \frac{\text{mass (g)}}{\text{molar mass (g/mol)}} \)

Front

What is Avogadro's number?

Back

Avogadro's number is \( 6.022 \times 10^{23} \) and represents the number of particles (atoms, molecules, etc.) in one mole of a substance.

Front

How do you convert grams to moles?

Back

Use the formula: \( \text{moles} = \frac{\text{grams}}{\text{molar mass}} \). For example, for 62 g of P (molar mass = 31 g/mol), it would be \( \frac{62}{31} = 2 \) moles.

Front

What is the molar mass of water (H2O)?

Back

The molar mass of water is 18.015 g/mol, calculated as follows: \( 2 \times 1.008 \text{ (H)} + 16.00 \text{ (O)} = 18.015 \text{ g/mol} \).

Front

How many molecules are in 1 mole of a substance?

Back

There are \( 6.022 \times 10^{23} \) molecules in 1 mole of any substance, according to Avogadro's law.

Front

What is the molar mass of sodium chloride (NaCl)?

Back

The molar mass of sodium chloride is 58.443 g/mol, calculated as follows: \( 22.990 \text{ (Na)} + 35.453 \text{ (Cl)} = 58.443 \text{ g/mol} \).

Front

How do you find the number of molecules in a given mass of a substance?

Back

Use the formula: \( \text{number of molecules} = \text{moles} \times 6.022 \times 10^{23} \). First, convert mass to moles, then multiply by Avogadro's number.

Front

What is the formula to calculate molar mass?

Back

Molar mass is calculated using the formula: \( \text{Molar Mass} = \sum (\text{atomic mass of each element} \times \text{number of atoms}) \).

Front

How many moles are in 47 g of KCl?

Back

To find the moles in 47 g of KCl (molar mass = 74.551 g/mol), use: \( \text{moles} = \frac{47}{74.551} \approx 0.63 \) moles.