Calculating Relative Formula Masses (CFU)

Front

What is the relative formula mass (M_r)?

Back

The relative formula mass (M_r) is the sum of the atomic masses of all the atoms in a chemical formula, expressed in atomic mass units (amu).

Front

How do you calculate the relative formula mass (M_r) of a compound?

Back

To calculate M_r, identify the number of each type of atom in the formula, multiply by their respective atomic masses from the periodic table, and sum the results.

Front

What is the atomic mass of Carbon (C)?

Back

The atomic mass of Carbon (C) is approximately 12 amu.

Front

What is the atomic mass of Hydrogen (H)?

Back

The atomic mass of Hydrogen (H) is approximately 1 amu.

Front

What is the atomic mass of Oxygen (O)?

Back

The atomic mass of Oxygen (O) is approximately 16 amu.

Front

Calculate the M_r of a molecule with 3 Carbon, 8 Hydrogen, and 1 Oxygen atom.

Back

M_r = (3 x 12) + (8 x 1) + (1 x 16) = 36 + 8 + 16 = 60.

Front

What is the M_r of potassium nitrate (KNO₃)?

Back

M_r = (1 x 39) + (1 x 14) + (3 x 16) = 39 + 14 + 48 = 101.

Front

What is the M_r of sulfuric acid (H₂SO₄)?

Back

M_r = (2 x 1) + (1 x 32) + (4 x 16) = 2 + 32 + 64 = 98.

Front

What is the M_r of iron (III) oxide (Fe₂O₃)?

Back

M_r = (2 x 56) + (3 x 16) = 112 + 48 = 160.

Front

What is the M_r of magnesium chloride (MgCl₂)?

Back

M_r = (1 x 24) + (2 x 35.5) = 24 + 71 = 95.