Chemistry

SPRING EXAMINATION STUDY QUESTIONS

 

1. (Chapter 12/Bonding) Draw Lewis structures for the following molecules:

a) N2 b) CH3Cl c) P2H2 d) H2SO4

 

2. (Chapter 12/Bonding) For the compounds in Question 1 a and b, indicate their geometry and whether they are polar or nonpolar.

 

3. (Chapters 20/Organic Chemistry) Draw structures for each of the following compounds:

a) butane b) 1-pentanol c) an aromatic carboxylic acid

d) propyl amine e) 2,2,4-trimethyl,3-ethylhexane f) an isomer of (e)

 

4. (Chapters 20/Organic Chemistry) For each of the following, identify the type of polymer and draw the polymer from the monomer(s):

 


a)

 

 

 

b) (polymer = Teflon)

 

 

 


5. (Chapter 13/Gases) What is the volume of a sample of gas containing 1.10 moles with a pressure of 1.80 atmospheres at 46C?

 

6. (Chapter 13/Gases) A sample of gas occupies a volume of 5.60 liters at STP.

a) What is the pressure of this sample when it is allowed to expand to 18.0 liters at 78C?

b) How many moles of gas are in the sample?

c) If the sample contains 7.50 grams of gas, what is the molar mass of this gas?

 

7. (Chapter 13/Gases) What is the density of ethane gas at 65C and 1.50 atmospheres pressure?

 

8. (Combination)

a) Write a balanced chemical equation for the reaction between solid magnesium metal and hydrochloric acid (HCl) to form aqueous magnesium chloride and hydrogen gas.

b) What mass of magnesium is needed to react completely with 23.0 mL of 0.500 M HCl?

c) What mass of magnesium is needed to produce 4.61 liters of hydrogen gas at STP?

 

9. (Chapter 15/Solutions) You may use the equation below to solve the following problems:

DTf = 1.86C x moles solute particles/kg water

a) What is the freezing point of a solution containing 117 g NaCl in 500. g of water?

b) How many moles of a nonelectrolyte in 50.0 g of water are required for a solution to have a freezing point of −2.79C?

 

10. (Chapter 15/Solutions) Review how to prepare a solution from either solid solute or by diluting a concentrated solution.

 

11. (Chapter 15/Solutions)

a) How many g of NaNO3 are needed to make 157 ml of a 3.00 M NaNO3 solution?

b) What is the concentration of NaNO3 in a solution prepared by diluting 240 ml of 0.500 M NaNO3 to 2.00 liters?

c) What is the mass percentage of a solution prepared by adding 2.00 moles of NaNO3 to 1.00 kg of water?

 

12. (Chapter 17/Equilibrium)

a) For the system at equilibrium,

2 NO2(g) N2O4(g) DH = -58 kJ,

what affect will each of the following have?

i) decreasing the volume iii) adding a catalyst

ii) increasing the temperature iv) adding more N2O4

b) Write an expression for K for this equilibrium. Calculate [N2O4] if the [NO2] = 0.010 M when the value for K is 10.0.

 

13. (Chapter 16/Acids & bases) Calculate the pH of each of the following solutions:

a) 0.010 M HClO4

b) 1.00 g NaOH dissolved in 250. ml water

 

14. (Chapter 16/ Acids & bases) What is the molarity of an NH3 solution if 12.0 liters of the NH3 solution are neutralized by 360 ml of 4.00 M HCl?

 

15. (Chapter 18/Oxidation-Reduction) For the following oxidation-reduction equation:

NO3-(aq) + Cu(s) NO(g) + Cu2+(aq)

a) identify the oxidation and reduction half-equations and label them.

b) balance the total equation for the reaction (adding H+ and H2O as needed).

c) Which substance is acting as an oxidizing agent? as a reducing agent?

 

16. (Chapter 18/Electrochemistry) For the following reaction (unbalanced):

Al(s) + Pb2+(aq) Al3+(aq) + Pb(s)

a) identify the oxidation and reduction half-equations and label them.

b) balance the total equation for the reaction.

c) draw a voltaic cell for this reaction, labelling anode, cathode, and the direction of flow of electrons, positive ions and negative ions.

 

 

ANSWERS TO SPRING EXAMINATION STUDY QUESTIONS

 

 


1. a) b) c) d)

 

 


2. a) linear, nonpolar b) tetrahedral, polar

 

3.

a) b) c)

 

 

 


d) e) f)

 

 

 

 

 

 

 


4. a) condensation polymer, polyester

 

 

 

 

 


b) addition polymer

 

 

 

 

 


5. V = ?, n = 1.10 moles, P = 1.80 atm, T = 46 C = 319 K.

16.0 L

 

6. a) V1 = 5.60 L; P1 = 1 atm, T1 = 273 K; P2 = ?; V2 = 18.0 L; T2 = 78 + 273 = 351 K.

= 0.400 atm

b) 5.60 L = 0.250 mol; or use at either T and P.

c) molar mass = = 30.0 g/mol

7. ethane = C2H6; molar mass = 2(12.0) + 6 (1.0) = 30.0 g/mole; 65C = 338 K

density = molar volume = volume when n = 1

= 1.62 g/L

8. a) Mg(s) + 2 HCl(aq) MgCl2(aq) + H2(g)

b) 23.0 mL = 0.140 g Mg

c) 4.61 L H2 = 5.00 g Mg

9. a) moles particles = 117 g NaCl = 4.00 mol particles

DTf = 1.86 = 14.9C; Tf = 0 14.9C = -14.9C

b) DTf = 2.79C, moles = ?, 50.0 g = 0.0500 kg H2O

DTf = 1.86 ; moles = = 0.0750 mol

 

10. Check out Procedure from the Solution Preparation experiment.

 

11. a) 157 mL = 40.0 g NaNO3

b) V1 x M1 = V2 x M2; V1 = 240 mL; M1 = 0.500 M; V2 = 2.00 L = 2000 mL; M2 = ?

M2 = = 0.0600 M

c) mass solute = 2.00 mol NaNO3 = 170. g NaNO3

mass solution = 1000 g H2O + 170. g NaNO3 = 1170 g

mass % = = 14.5 %

 

12. a) i) shift to right (shift to side with fewer moles); ii) shift to the left (shift in endothermic direction to use up heat); iii) no shift; iv) shift to left (use up some of the N2O4 added).

b) K = ; [N2O4] = K x [NO2]2 = 10.0 (0.010)2 = 0.0010 M

13. a) HClO4 = strong acid, so [HClO4] = [H+] = 0.010 M = 1 x 10-2 M; pH = 2.0

b) NaOH = strong base, so [NaOH] = [OH-] = = 0.100 M NaOH

[OH-] = 0.100 M = 1 x 10-1 M; [H+] = 1 x 10-13 M; pH = 13.0

 

14. VA x MA = VB x MB; VA = 360 mL = 0.360 L; MA = 4.00 M; VB = 12.0 L; MB = ?

MB = = 0.120 M

 

15. a) oxidation: Cu(s) Cu2+(aq) + 2 e-; reduction: 3 e- + 4 H+ + NO3-(aq) NO(g) + 2 H2O

b) overall: 2 NO3-(aq) + 3 Cu(s) + 8 H+(aq) 2 NO(g) + 3 Cu2+(aq) + 4 H2O

c) NO3- is the oxidizing agent (its reduced); Cu is the reducing agent (its oxidized).

 

16. a) oxidation: Al(s) Al3+(aq) + 3 e-; reduction: Pb2+(aq) + 2 e- Pb(s)

b) 2 Al(s) + 3 Pb2+(aq) 2 Al3+(aq) + 3 Pb(s)

c)