I. Good things to know
â€¢ stoichiometry, chemical formula
â€¢ ionic compound ïƒ formula unit
â€¢ hydrate, anhydrous
â€¢ molecular compound ïƒ molecule
â€¢ mole, Avagadroâ€™s Number
â€¢ formula mass, molar mass, molecular mass
â€¢ Standard Temperature and Pressure (STP)
â€¢ percent yield
â€¢ limiting reactant, excess reactant
â€¢ Law of Definite Proportions, Law of Multiple Proportions
â€¢ empirical formula, molecular formula
â€¢ mass spectrometer
â€¢ titration, standard solution, unknown solution
1) Calculate the formula mass for:
a) HF b) SiO2 c) SiF4
1 + 19 = 20.0 28.1 + 32 = 60.1 28.1 + 4(19) = 104
2) Calculate the number of moles of HF molecules in:
a) 0.385 g HF b) 3.02 x 1024 molecules of HF
c) 50.0 mL of a 0.600M HF solution d) 1.50L of HF at 0.989 atm of pressure ...view middle of the document...
92g of silicon tetrafluoride in problem (c), what is the percent yield?
4) Find the percent composition of:
a) SiO2 ïƒ 28.1 + 2(16) = 60.1 b) Ba(NO3)2 ïƒ 137 + 2(14) + 6(16) = 261
5) How would you prepare 1.00 L of a 4.00 M H2SO4 solution from concentrated H2SO4 (18 M)?
6) A sample of 0.6760g of an unknown compound containing barium ions (Ba+2) is dissolved in water
and treated with an excess of Na2SO4. If the mass of the barium sulfate precipitate formed is
0.4105g, what is the percent by mass of barium in the original unknown compound?
7) An ion containing only oxygen and chlorine is 31% oxygen by mass. What is the empirical formula?
8) A hydrocarbon was found to be 20% hydrogen by weight. If one mole of the hydrocarbon has a
mass of 30 grams, what is its molecular formula?
9) If you add 20.0 mL of 0.100 M iron(III) nitrate to 20.0 mL of 0.100M sodium hydroxide, how many grams of precipitate will be formed? Write the net ionic equation for the reaction.
10) If it requires 25.0 ïL of a 0.500M KI solution to precipitate all of the lead(II) ions out of a 100.0
mL sample, what is the concentration of the lead ions?
11) What is the concentration of each ion in a 0.300 M solution of Na3PO4? Na3PO4 ïƒ 3 Na+1 + PO4-3
[Na+1] = 0.900M [PO4-3] = 0.300M
12) If you titrate 10.0 mL of an unknown monoprotic acid with a solution of 0.600 M NaOH, and it requires 25.4 mL of the base to reach the equivalence point, what is the concentration of the acid?
13) What is the concentration of an unknown H2SO4 solution if it requires 156.3 mL of 1.50M NaOH standard to titrate a 100.0 mL sample of the unknown?
14) In your lab, you titrated hydrogen peroxide with potassium permanganate:
6 H+1 + 2 MnO4-1 + 5 H2O2 ïƒ 5 O2 + 2 Mn+2 + 8 H2O
If 36.44 mL of a 0.01652 M KMnO4 solution is required to completely oxidize 25.00 mL of
a H2O2 solution, calculate the molarity of the peroxide solution.