SL Chem - Unit #2: Combustion and Hydrate Analysis

Combustion Analysis

A method used to determine an elements % composition

Combustion analysis process…

• Hydrocarbons are burned in pure oxygen to produce carbon dioxide and water 

  • CuO oxidises C and CO which forms CO₂

  • All the hydrogens form H₂O

• The mass of H₂O and CO₂ are absorbed separately and their masses are than used to determine their percentage composition

  • This helps determine the amount of C and H in the fuel that was being used to burn

Hydrate Analysis

Hydrates are ionic compounds with water incorporated into their crystal structure

• NOT LIKE AN AQUEOUS SOLUTION

The analysis is done by heating the hydrate until it’s an anhydrous

Percentage of Water in the hydrate

Normal percent composition formula but for the whole water molecules multiplied by its coefficient

Mass of water in a specific weight of the compound

1. Using the percentage of water divide by 100, then Multiply by the weight of the compound

2. Formula

Coefficient on the Hydrate

1. Write down the balanced equation

2. Write down the mass of the hydrate and the ionic compound that forms after being heated 

3. Determine the mass of the water that comes off after being heated using the law of conservation of mass

4. Solves for the moles of the compound and water

5. Divide the both moles by the lowest mole ratio

6. The ratio that you get is then the coefficient on water