Calculate the percentage by mass of the indicated element in the following compounds: (c) sulphur in magnesium sulphate, MgSO4, a substance used as a drying agent

Verified step by step guidance

1. Identify the molar mass of each element in the compound MgSO4. Magnesium (Mg) has a molar mass of approximately 24.31 g/mol, sulphur (S) has a molar mass of approximately 32.07 g/mol, and oxygen (O) has a molar mass of approximately 16.00 g/mol.
2. Calculate the molar mass of the compound MgSO4 by adding the molar masses of its constituent elements. The formula MgSO4 includes one magnesium atom, one sulphur atom, and four oxygen atoms.
3. Determine the mass of sulphur in one mole of MgSO4 using the molar mass of sulphur.
4. Calculate the percentage by mass of sulphur in MgSO4 by dividing the mass of sulphur in the compound by the total molar mass of the compound, then multiply by 100 to convert it to a percentage.
5. Express your result as a percentage, which represents the mass percentage of sulphur in magnesium sulphate.

Key Concepts

Molar Mass

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 the atoms in a chemical formula. For magnesium sulfate (MgSO4), the molar mass is determined by adding the molar masses of magnesium (Mg), sulfur (S), and oxygen (O) in the compound.

Percentage by Mass

Percentage by mass is a way to express the concentration of an element in a compound. It is calculated by dividing the mass of the element of interest by the total mass of the compound, then multiplying by 100. This calculation helps in understanding the composition of compounds and is essential for stoichiometric calculations in chemistry.

Stoichiometry

Stoichiometry is the branch of chemistry that deals with the quantitative relationships between the reactants and products in a chemical reaction. It involves using balanced chemical equations to calculate the amounts of substances consumed and produced. Understanding stoichiometry is crucial for accurately determining the percentage by mass of elements in compounds, as it provides the necessary relationships between the quantities involved.