Question

4. If you burn 2.3 grams of a compound off the top of crème brulee, and it has carbon, oxygen, and hydrogen, would you be able to determine the empirical formula if you collected 2.7 grams water, and 4.4 grams carbon dioxide, and if yes, what is the empirical formula of the compound?

5. Which of the following has more atoms? 5.0 grams F2 or 8.0 grams S?

6. When you burn gasoline, a few different reactions can happen. One is C8H18(l) + O2(g)  H2O(l) + CO2(g) If you react 5.0 kg gasoline with 1.0 kg oxygen, how much water could you form?

7. Balance, identify the oxidizing agent and the reducing agent in the following reaction by assigning oxidation numbers, and give the phase (s, l, g, aq) of each reactant and product. H2O + Zn + HCl(aq)  H2 + H2O + ZnCl2

8. How many liters of 0.500 M H3PO4 would it take to react with 8.00 L of 0.100 M NaOH?

9. If you want to dilute some salt water solution from 3.0 M NaCl to 0.20 M NaCl and have 9.0 L after dilution, what would you need for starting volume?

Answer 1

4. ANSWER: YES

no of mol of CO2 PRODUCED = 4.4/44 = 0.1 mol

    no of mol of Carbon present in sample = 0.1 mol

   no of mol of water produced = 2.7/18 = 0.15 mol

    no of mol of H present in sample = 0.15*2 = 0.3 mol

     no of mol of O in sample = (2.3 - (0.1*12+0.3*1))/16    = 0.05 mol

   simplest ratio

C = 0.1/0.05 = 2

H = 0.3/0.05 = 6

o = 0.05/0.05 = 1

empirical formula = C2H6O

5. NO Of mol of F2 = 5/38 = 0.131 mol

   NO Of mol of S = 8/32 = 0.25 mol

answer: F2 ( 0.131*2 = 0.262 mol F-atoms,   no of mol is directly proportional to atoms/molecules)

6.   2C8H18(l) + 25O2(g) --> 18H2O(l) + 16CO2(g)

no of mol of gassoline = 5/114.23 = 0.0438 Kmol

   no of mol of o2 = 1/32 = 0.03125 kmol

limiting reactant = o2

no of mol of water produced = 0.03125*18/25 = 0.0225 kmol

mass of water produced = 0.0225*18

                        = 0.405 kg