Mole Conversions & % Composition

Front

What is a mole in chemistry?

Back

A mole is a unit of measurement used to express amounts of a chemical substance, defined as exactly 6.022 x 10^23 particles (atoms, molecules, ions, etc.).

Front

How do you convert grams to moles?

Back

To convert grams to moles, divide the mass of the substance (in grams) by its molar mass (in g/mol).

Front

What is the molar mass of CO2?

Back

The molar mass of CO2 (carbon dioxide) is approximately 44.01 g/mol.

Front

How many liters are in 1 mole of a gas at STP?

Back

At Standard Temperature and Pressure (STP), 1 mole of an ideal gas occupies 22.4 liters.

Front

What is the formula to calculate % composition by mass?

Back

% Composition by mass = (mass of element in 1 mole of compound / molar mass of compound) x 100.

Front

Calculate the % composition of sodium in NaCl.

Back

% Composition of Na in NaCl = (mass of Na / molar mass of NaCl) x 100 = (22.99 g / 58.44 g) x 100 = 39%.

Front

What is the % composition of aluminum in Al2(SO4)3?

Back

% Composition of Al = (mass of Al in 1 mole of Al2(SO4)3 / molar mass of Al2(SO4)3) x 100 = 15.77%.

Front

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

Back

To find the number of molecules, convert grams to moles using molar mass, then multiply by Avogadro's number (6.022 x 10^23).

Front

True or False: 1 mole of Ca and 1 mole of Na have the same number of atoms.

Back

True. 1 mole of any substance contains the same number of entities (atoms, molecules, etc.).

Front

What is the molar mass of P2O5?

Back

The molar mass of P2O5 (diphosphorus pentoxide) is approximately 283.88 g/mol.