1. Good Morning! Today is Tuesday, January 5, 2016 HW Due: Balancing Review Please put in the Inbox Do-Now: What do you think the term stoichiometry means?

2. Stoichiometry Calculating the amounts of substances in chemical reactions

3. Why do we need stoichiometry? A chemist didn’t put enough magnesium in a synthesis reaction to make magnesium oxide. Mg + O 2 → 2 MgO A chemist didn’t supply enough oxygen to combust benzene. 2 C 6 H 6 + 12 O 2 → 12 CO 2 + 6 H 2 O Excess sodium bicarbonate was added to hydrochloric acid HCl + 2 NaHCO 3 → NaCl + H 2 O + CO 2

4. Balancing chemical equations provides chemists with the quantities needed to determine amounts of products or reactants in an experiment In every chemical reaction, the mass and number of atoms are conserved following the LAW OF CONSERVATION

5. The Mole Ratio A mathematical relationship between the moles of one substance and another substance in a reaction. It allows chemists to convert between moles of reactants and moles of products, as well as balance a reaction.

6. Calculating the Mole Ratio 2 HgO → 2 Hg + O 2 1.What is the mole ratio of HgO to Hg? 2.What is the mole ratio of HgO to O 2 ?

7. Conclusion Using the equation below, calculate the mole ratio of N 2 to NH 3. ___ N 2 + ___ H 2  ___ NH 3

8. Mole Ratio Practice Problems

9. Mole Roadmap And the Mole Ratio Moles Grams ÷ molar mass x molar mass Moles Unknown Moles Known Moles Grams ÷ molar mass x molar mass Known Chemical Mole Ratio Unknown Chemical

10. How many moles of O 2 are formed from a decomposition reaction using 0.4 moles of HgO? ___ HgO → ___ Hg + ___ O 2 Moles Grams

11. How many moles of HCl are needed to produce 0.670 moles of CaCl 2 in the following reaction: ___ Ca(OH) 2 + ___ HCl → ____ CaCl 2 + ____ H 2 O Moles Grams

12. Conclusion If 0.20 mole of O 2 reacted, how many moles of N 2 O 3 would be formed? ___ N 2 + ___ O 2 → ___ N 2 O 3

13. Homework Complete the “Mole Ratio Practice Problems” for tomorrow