Supplemental Instruction
Iowa State University / Leader: / Grant DeRocher
Course: / Chem 167
Instructor: / Houk
Date: / 02/07/13
1. 1 (12 pts) Fill in the table below with the correct number of protons, neutrons and electrons
# of protons# of neutrons# of electrons
36Cr-______
75Sn2+______
43K3-______
54Ar______
2. The element Ga has a molar mass of 69.723 g/mole and has only two isotopes. Isotope A has mass number68.926 g/mole; Isotope B is .797 g/mole heavier than Isotope A. What are the mass numbers (g/mole) and abundances of the two isotopes? Show work for partial credit; no credit for guessing. Keep three sig figs.
Mass%
NumberAbundance
Isotope A______
Isotope B______
3. Calculate the molar mass of the following organic compounds. Use the following simple atomic masses: H = 1.00 C = 12.00 N = 14.00 O = 16.00 g/mole. Do not worry about sig figs.
A. An alkene with three carbon atoms.(Draw picture first)
MM = ______g/mole
B. An amide with 7 hydrogen and 3 carbon atoms
MM = ______g/mole
C. Dimethal Ether-ether with 6Hydrogens
MM= ______g/mole
4. Given 115 mL of an aqueous solution of potassium sulfate is analyzed and found to have 250mg of potassium. 75 mL of water are added. What is the molar concentration of potassium sulfate? (moles per liter) in the second solution after the 75 mL of water is added? Follow sig figs. Atomic weights: potassium=39.098g/mol and sulfate= 96.061g/mol
5. Copper reacts with sulfuric acid according to the following equation:
2H2SO4 +Cu CuSO4 + 2H2O + SO2 (not balanced)
How many grams of sulfur dioxide are created by this reaction if 14.2 g copper reacts with 18.0 g of sulfuric acid? Use 3 sig figs.
6. (borrowed from SI Session 6 worksheet. This was a problem #9 we never got to yet.) If 21 g of H2S is mixed with 38g O2 and it forms 31 g of SO2, what is the percent yield? (Two step process).
2H2S + 3O2 2SO2 + 2H2O
7. The amount of one gas is under the following conditions. What is the gas? No guessing. Must show work.
Mass= 57.33 g Temperature= 35 degrees C Pressure= 1.73 atm
Volume= 10.0-L R= .08206 L*atm/mol*K
Things to know how to do:
-balance equations
-be able to name and identify common ionic and covalent bonds
-use ratios to cancel units to find desired answer
-be able to tell if your answer is reasonable for the problem
-convert grams to moles and vice versa. (molar mass) and how to use it in problems
-know functional groups
-know formula from a reduced picture
-know common cations and anions
-know which ionic compounds are soluble and which are insoluble
-know which acids and bases are strong and weak and what that means about dissociation
-know the difference between molecular and empirical formula and know how to find both.
- know what molar concentration is
-know dilution equation and how to solve dilution problems
- know the basic alkanes
-know how to do stoichiometry problems (using molar ratios from balanced eqnsetc)
-know how to find a limiting reactant
-know how to find theoretical and percent yields
-know the ideal gas law and how to manipulate it to solve for what you are trying to find
-know how to find partial pressures and total pressure of gas mixtures
-know the kinetic molecular theory of gasses and when it does not work
-know vander wall’s formula and how to use it