How do you find the relative formula mass of a compound?

You find the relative formula mass of a compound by adding up the relative atomic masses of all the atoms in its formula.

The relative formula mass (Mr) of a compound is a measure of the sum of the relative atomic masses of the atoms in the numbers shown in the formula. In other words, it's the total mass of all the atoms in a molecule or formula unit of a compound. This is calculated using the periodic table, where each element is assigned a relative atomic mass.

To calculate the relative formula mass, you need to know the formula of the compound and the relative atomic masses of the elements. For example, let's consider water (H2O). The relative atomic mass of hydrogen (H) is 1, and there are two hydrogen atoms in water. The relative atomic mass of oxygen (O) is 16. So, the relative formula mass of water is (2*1) + 16 = 18.

For a more complex compound like magnesium carbonate (MgCO3), the calculation would be as follows: the relative atomic mass of magnesium (Mg) is 24, carbon (C) is 12, and oxygen (O) is 16. However, there are three oxygen atoms in this compound. So, the relative formula mass of magnesium carbonate is 24 + 12 + (3*16) = 84.

Remember, the relative formula mass of a compound is not the same as the mass of one molecule of that compound. It's a ratio, comparing the mass of one molecule (or formula unit) of the compound to 1/12th the mass of a carbon-12 atom. This is a fundamental concept in chemistry, as it allows us to compare different substances on a level playing field.