Chemistry 201/211Fall 2004OregonStateUniversity

Worksheet 3October 14, 2004

1) Consider the mixture of iodine gas and chlorine gas represented in the box below. (Iodine atoms are represented as squares, chlorine atoms as circles.)

What will the contents of the box look like if the molecules undergo the reaction

I2(g) + 3Cl2(g) 2ICl3(g)

For the next two problems, circle the true statement and make the false statements true.

2.) If 1.00 mol of ammonia reacts with 1.00 mol of oxygen according to the reaction

4NH3(g) + 5O2(g) 4NO(g) + 6H2O(l)

a.)All the oxygen is consumed.

b.)4.00 mol of NO is produced.

c.)1.50 mol of water is produced

d.)0.20 mol of ammonia is left over.

e.)The statement does not provide enough information to determine percent yield.

3.) In the reaction of 2.0 mol CCl4 with an excess of HF, 1.7 mol CCl2F2 is obtained

CCl4(l) + 2HF(g) CCl2F2(l) + 2HCl(g)

a.)The theoretical yield for CCl2F2 is 1.7 mol

b.)The actual yield for CCl2F2 is 1.0 mol

c.)The percent yield for the reaction is 85%

d.)Theoretical yield cannot be determined unless the exact amount of HF used is known.

4.) Which of the following best describes the preparation of 0.500 L of aqueous solution of 1.00 M NaCl?

a.)place 29.2 g NaCl(s) in a flask; dilute to a total volume of 5.00102 mL

b.)place 58.4 g NaCl(s) in a flask; add 5.00102 mL of water

c.)place 0.500 L of water in a flask and add 29.2 g NaCl

d.)place 11.5 g Na(s) and 17.7 g Cl2(g) in a flask; dilute to 5.00102 mL

e.)none of the above

5.) Phosphoric acid can be neutralized by sodium hydroxide according to the equation

__H3PO4 + __NaOH  __Na3PO4 + __H2O

What volume of 0.176 M NaOH would be required to neutralize 5.00 mL of 14.6 M concentrated phosphoric acid?

6.) Use the table on page 80 of your book to answer the following question.

Suppose you have a solution that might contain any or all of the following cations: Na+,Ca2+, Ag+, Ba2+. Addition of HCl solution causes a precipitate to form. After filtering off the precipitate, H2SO4 solution is added to the resultant solution and another precipitate forms. This is filtered off, and a solution of Na3PO4 is added to the resulting solution. No precipitate is observed. Which ions are present in each of the precipitates? Which of the four ions listed above must be absent from the original solution?

7.) Write a balanced net ionic equation for each of the following reactions in water

a.)nitric acid and barium hydroxide

b.)barium nitrate and lithium sulfate

c.)analine (C6H5NH2) and sulfuric acid

8.) Calculate the molarity of 12.26 g H2SO4 in 250.0 mL of solution. One method used commercially to peel potatoes is to soak them in a solution of NaOH for a short time, remove them from the NaOH, and spray off the peel. The concentration of NaOH is normally in the range 3 to 6 M. The NaOH is analyzed periodically to ensure quality. In one such analysis, 45.7 mL of the above solution is required to react completely with a 20.0 mL sample of NaOH:

H2SO4(aq) + 2NaOH(aq) 2H2O(l) + Na2SO4(aq)

What is the concentration of the NaOH in solution?

9.) To determine the SO2 content of a preservative, 0.3111 g is weighed into 50.00 mL of 0.05238 M I2 where it reacts

SO2 + 2H2O + I2 HSO4- + 3H+ + 2I-

The excess I2 is then titrated with 17.22 mL of 0.1101 M Na2S2O3

I2 + 2S2O32- 2I- + S4O62-

What is the weight of the SO2 in the preservative? Not all of the information given will be needed.

10.) Balance the following unbalanced redox equation in acid.

Zn(s) + VO2+(aq) Zn2+(aq) + V2+(aq)

a.)Write the oxidation number for each atom in the reactants and products

b.)Write the balanced oxidation and reduction half reactions

c.)Write the net balanced equation