1. Year 10 C Pathway Mr. D. Patterson

2. Outcomes  Be able to calculate the unknown mass of a substance from the known mass of a substance appearing in a balanced chemical equation

3. Recap  Stoichiometry is the study of relative quantities in a chemical reaction

4. Adding an extra step or two..  An average egg weighs 48 g  What mass of eggs do I need to make 3 cakes?  How did you answer this question?

5. Adding an extra step or two..  The mass of a product or reactant can be found from the amount of moles  The moles of a product or reactant can be found from the mass

6. From mass to mass Find moles of known Find moles of unknown Find mass of unknown Start with this step if you have been given the mass of a substance to start from Eg: Find the number of moles of HCl if 36 g of Mg is reacted. End with this step if you have been asked to find the mass of a substance Eg: Find the mass of oxygen gas required to combust 7 moles of methane The first and last step are not always required. It depends on what the question asks and the information that is given. The middle step is always required. It is the step that calculates the unknown substance from the known one.

7. Example problem  Determine the mass of hydrochloric acid required to completely react with 87 g of magnesium  Which steps are required? Find moles of known Find moles of unknown Find mass of unknown

8. Example problem  Determine the mass of hydrochloric acid required to completely react with 87 g of magnesium Find moles of known

9. Example problem  Determine the mass of hydrochloric acid required to completely react with 87 g of magnesium Find moles of unknown

10. Example problem  Determine the mass of hydrochloric acid required to completely react with 87 g of magnesium Find mass of unknown

11. Example Problem  What mass of carbon dioxide can be produced from 3.5 moles of oxygen gas when it combusts carbon?  Which steps are required? Find moles of known Find moles of unknown Find mass of unknown

12. Example Problem Find moles of unknown Find mass of unknown

13. Outcomes  Be able to calculate the unknown mass of a substance from the known mass of a substance appearing in a balanced chemical equation  Checkpoint 10.5, 10.6, 10.7  Set 22-24