Other Conversions

- Volume @STP can be found using the conversion factor 22.4 L/mol
- Heat can be included as a seperate term in chemical reactions (Enthalpy)
i) Rxns that release heat are exothermic
ii) Rxns that absorb heat are endothermic
iii) Both can be used in Stoichiometry

Examples

If 5.0g of Potassium chlorate decomposes according to the reaction below, what volume of Oxygen gas (@STP) is produced?

2KClO3 ---> 2KCl+ 3O3

5.0g x 1mol/122.6 x 3/2 x 22.4 L/ 1mol = 1.4 L

When Zinc reacts w/Hydrochloric acid exactly 1.00 L of Hydrogen gas is produced @STP. What mass of Zinc was reacted?

Zn + 2HCl ---> H2 + ZnCl2

1.00L x 1mol/22.4 L x 1/1 x 65.4 g/1 mol = 2.82 g

In the formation of Copper (III) Oxide 3.5g of Copper react. How many litres of Oxygen @STP are needed?

2Cu + O2 ---> 2 CuO

3.5g x 1mol/63.5g x 1/2 x 22.4 L/1mol = 0.62 L