Chemistry 102 Worksheet

A) To prepare 250 mL of glucose,C6H1206, with a concentration that is 0.0500 M, how many grams of glucose are needed?

B) Sulfuric acid is spilled while Dr. Jones is showing a demo to the class. Sodium bicarbonate is used to neutralize it according to the equation: 2NaHC03 + H2SO4 => Na2SO4 + 2CO2 + 2H20. If 40 mL of 6.0 M H2SO4 are spilled, what is the mass of NaHC03 Dr. Jones needs to add to completely neutralize the acid?C) You are Bond, James Bond. While at a soiree with the European jet set, you drink a 0.25 L glass of champagne that a lovely. young lady, handed you. A few minutes later, Q pops into your wristcom and tells you that the lovely young lady was Ursula Onnatop. She wants revenge for your having killed her sister Xenia and put 2.0 nanograms of Blyotoxin' in your champagne. You recall from your Secret Agent Chemistry Manual' that the molar mass of Blyotoxin' is 344.22 g/mol, and that its toxicity is based on the concentration of the dose

Are you? a) Fine   b) feeling a little ill   c) puking your guts out   d) dead

Chemistry 101Z, Section 62
Workshop #5: Reactions and limiting Reagents

Sept. 14th, 1999

1. An Activity! The Nuts and Bolts of Chemistry.... For all that follows,
   • B is the symbol for a bolt atom, 
     and N is the symbol for a nut atom.
          First, a little bit of background: You are in a new universe. This universe is called the Hardware Store. This universe consists of only 2 elements: nuts and bolts. One nut atom is one nut and one bolt atom is one bolt. Like the noble gases, nut and bolt atoms are only found alone in nature (no dimers, no compounds). But under special laboratory conditions, they can (and do) react .... (No lab goggles required. Take your molecules apart after each step.) 
    
   1. First form BN2 and write a balanced equation. 
       
   2. b) Now create 2BN and write a balanced equation. What's the difference between this and step a? What do subscripts tell us? What do coefficients tell us?
   3. Combine your reactants to make as many BN molecules as you can.
      1. How many molecules did you get?
      2. What was your limiting reactant, Nuts or Bolts?
      3. Was your limiting reactant the one you had fewest of?
      4. Why does there have to be something left over? That is, why couldn't you just add Nut or Bolt atoms until everything was used up?
   4. Now suppose the hardware aisle undergoes a major change in chemistry, and BN molecules can no longer be formed, only BN3 molecules. Make as many BN3 molecules as you can.
      1. How many, molecules did you get?
      2. What was your limiting reactant, Nuts or Bolts?
      3. Was your limiting reactant the one you had fewest of?
      4. Why does there have to be something left over? That is, why couldn't you just add Nut or Bolt atoms until everything was used up?
2. An unknown compound consists only of carbon hydrogen, and oxygen. You know that it is 40.0% carbon by mass.
   1. What other information do you nedd to solve for the empirical formula?
   2. What next? Supposing you had th the "other information", explain why you would do each subsequent step.
   3. Why can't you find the molecular formula in a problem like this?
3. Discuss #1, 2, 6, 9, 10, and 11 on pg. 123-4 of your text.
4. In doing stoichiometry problems, why do we ALWAYS work with moles? Why don't we use masses?
5. You're given the following equation:   3A + B 4 C + D 
   2 moles of A react with 2 moles of B. Which of the following is true? Explain.
   1. B is the limiting reactant because there are fewer moles of A than B.
   2. B is the limiting reactant because 3 A molecules react with I B molecule.
   3. A is the limiting reactant because 3 moles of A are needed and there is only l
   4. A is the limiting reactant because 6 moles of A are needed and there are only 2. e) Neither A nor B is limiting because we have equal amounts of each.
6. The, thermite reaction is really, really cool. I hope Dr. Jones does it this semester. The unbalanced reaction is the following:
   
   _AI(s) + _Fe3O4(s) => _A12(s) + _Fe(s) 
   
   Balance the reaction and answer the following:
   1. If 10.0 g Fe304 is reacted with 5.00 g Al. How many grains of A1203 can be theoretically produced?
   2. How much excess reactant is left over after the reaction is complete? Prove that mass has been conserved.