Lecture 99/19/05  Exam on Friday  Review Session Tuesday, Sept. 20 th 5:30-6:30 p.m TSC 117

 Thallium has an atomic weight of amu, and has 2 isotopes, Tl-203 and Tl-205. What are the abundances of these isotopes ?

 How many moles are in 16.5 g of oxalic acid (H 2 C 2 O 4 )?

Practice  Predict the charge on: Ba I

Practice  Give formula for: Nitrate Sulfate

Practice  What is the charge on each ion? K 2 S (NH 4 ) 3 PO 4

Practice  Name the following: K 2 S SeO 4 2- and SeO 3 2-

Practice  Zircon is composed of 49.76% Zr, 15.32% Si, and the remainder is oxygen. What is the empirical formula of zircon?

Practice  Which of the following compounds contain the greatest percentage of carbon by mass? C 10 H 8 C 18 H 12 C 24 H 12 C 16 H 10

Fill in the table: Symbol # of protons # of neutrons # of electrons

 The amount of matter in a system does not change  An equation must be balanced Same number of atoms on both sides. Stoichiometry  Stoichiometry Law of Conservation of Matter

Chemical Equations 4 Al(s) + 3 O 2 (g) ---> 2 Al 2 O 3 (s) reactants products  Stoichiometric coefficients 4 Al atoms + 3 O 2 molecules ---give---> 2 molecules of Al 2 O 3 4 Al atoms + 3 O 2 molecules ---give---> 2 molecules of Al 2 O 3 4 moles of Al + 3 moles of O 2 ---give---> 2 moles of Al 2 O 3 4 moles of Al + 3 moles of O 2 ---give---> 2 moles of Al 2 O 3  Pay attention to (s), (g), (l) and (aq)

Balancing Equations ____C 3 H 8 (g) + _____O 2 (g) ---->____CO 2 (g) + ____H 2 O(g) ____B 4 H 10 (g) + _____O 2 (g) ---->___B 2 O 3 (g) + ____H 2 O(g)