8AB Mole Calculations

Front

What is the molar mass of a compound?

Back

The 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 the molecular formula.

Front

How do you calculate the molar mass of Zn(C₂H₃O₂)₂?

Back

To calculate the molar mass, sum the atomic masses: Zn (65.4 g/mol) + 2(C₂H₃O₂) = 2(2*12.01 + 3*1.01 + 16.00) = 2(24.02 + 3.06 + 16.00) = 2(43.08) = 86.16 g/mol. Total = 65.4 + 86.16 = 151.56 g/mol.

Front

What is the molar mass of calcium hydroxide, Ca(OH)₂?

Back

The molar mass is calculated as follows: Ca (40.08 g/mol) + 2(O) (16.00 g/mol) + 2(H) (1.01 g/mol) = 40.08 + 32.00 + 2.02 = 74.10 g/mol.

Front

How do you find the number of moles from mass?

Back

Use the formula: Number of moles = mass (g) / molar mass (g/mol).

Front

How many moles are in 20g of magnesium?

Back

Using the molar mass of magnesium (24.31 g/mol): Number of moles = 20 g / 24.31 g/mol = 0.82 moles.

Front

What is Avogadro's number?

Back

Avogadro's number is 6.022 x 10²³, which is the number of particles (atoms, molecules, etc.) in one mole of a substance.

Front

How do you calculate the number of molecules from moles?

Back

Use the formula: Number of molecules = moles x Avogadro's number.

Front

How many molecules are in 135g of Teflon (C₂F₄)?

Back

First, calculate the molar mass of C₂F₄: (2*12.01) + (4*19.00) = 24.02 + 76.00 = 100.02 g/mol. Then, find moles: 135 g / 100.02 g/mol = 1.35 moles. Finally, calculate molecules: 1.35 moles x 6.022 x 10²³ = 8.13 x 10²³ molecules.

Front

What is the mass of one mole of sulfur?

Back

The molar mass of sulfur (S) is 32.07 g/mol.

Front

What is the difference between atomic mass and molar mass?

Back

Atomic mass is the mass of a single atom, while molar mass is the mass of one mole of a substance, which includes all atoms in the molecular formula.