Calculating the Formulas of Hydrated Salts

Professor Dave explains how to calculate the formula of a hydrated salt. He introduces the concept of salts and hydrates, and describes an experiment to determine the number of water molecules in a hydrate. By heating the hydrate, the water is vaporized, allowing the mass of the anhydrous salt to be measured. The mass of water is calculated by difference, and both masses are converted to moles. The ratio of moles of salt to water is determined, allowing the complete formula of the hydrated salt to be written. This process demonstrates how simple calculations can reveal molecular structures.

What is the term used for any compound consisting of formally charged ions?

• Element

• Covalent Compound

• Salt

• Molecule

What is the first step in determining the number of water molecules in a hydrated salt?

• Adding more water to the salt

• Cooling the salt

• Heating the salt to remove water

• Dissolving the salt in water

After heating, what is the mass of the anhydrous magnesium carbonate obtained?

• 15.67 grams

• 8.09 grams

• 7.58 grams

• 0.09 grams

How many moles of water are found in the magnesium carbonate hydrate after calculations?

• 1.00 moles

• 0.45 moles

• 5.00 moles

• 0.09 moles

What is the ratio of water molecules to magnesium carbonate in the hydrate?

• 1:2

• 1:1

• 1:3

• 1:5