CHEMICAL REACTIONS II
UNIT 6 SOLUTIONS AND GASES
Tuesday, May 10, 2011
NAME:______
AHS Instructor Ms. Kasia Room 109
TOTAL POINTS /50
PART A Correct /16
Explanation /16
PART B /16
BONUS /2
BONUS (1 pt each):
1. Which unit do you feel you need to review the most?
2. What is one think you liked about this unit?
Question # / Objective / Total Correct / Percent CorrectSWBAT define solution.
2, 14, 10 / SWBAT describe the factors that affect solubility. / /3
6, / SWBAT determine whether or not a compound is soluble in water using a solubility table. / /1
7, 8, 15, 18, / SWBAT determine the saturation point of a solution using Table G. / /4
16, 17, / SWBAT calculate the concentration of a solution. / /2
3, 5, 13, / SWBAT describe the effects of a solute on the boiling point and freezing point of a solution. / /3
SWBAT define an ideal gas.
29 / SWBAT explain the effects of pressure, volume, and temperature on ideal gases.
12, 20, 28, / SWBAT use the combined gas law to solve for pressure, volume, and temperature of an ideal gas. / /3
4, 11, 25 / What is vapor pressure and how do we use Table H? / /3
REVIEW OBJECTIVES
19 / SWBAT describe the separation techniques of mixtures. .(Unit 1 Introduction to Matter) / /1
24 / SWBAT define equilibrium. (Unit 5 Kinetics and Equilibrium) / /
9 / SWBAT calculate density.(Unit 2 Mathematics of Chemistry) / /1
21, 27 / SWBAT convert units. (Unit 2 Mathematics of Chemistry) / /2
22, 26 / SWBAT explain collision theory. (Unit 5 Kinetics and Equilibrium) / /2
1 / SWBAT name ionic compounds (Unit 1 Chemical Bonding) / /1
25 / SWBAT determine the effect of stress on a chemical system in equilibrium. (Unit 5 Kinetics and Equilibrium) / /1
Part A
Directions (1-16): For each statement or question, circle your best answer. In the Explanation section, explain how you arrived at your answer. Some questions may require the use of the Reference Tables.
1. What is the formula of titanium (II) oxide?(1) TiO
(2) TiO2
(3) Ti2O
(4) Ti2O3 / Explanation
O-2 bonds to Ti+2, so given criss cross rule : TiO
2. The solubility of KClO3(s) in water increases as the
(1) temperature of the solution increases
(2) temperature of the solution decreases
(3) pressure on the solution increases
(4) pressure on the solution decreases / Explanation
Labà when temperature increased, solids dissolved better
3. Compared to 0.1 M aqueous solution of NaCl, a 0.8 M aqueous solution of NaCl has a
(1) higher boiling point and a higher freezing point
(2) higher boiling point and a lower freezing point
(3) lower boiling point and a higher freezing point
(4) lower boiling point and a lower freezing point / Explanation
Higher concentration means MORE PARTICLES! When there is more particles, H Bpt and L Fpt
4. The boiling point of a liquid is the temperature at which the vapor pressure of the liquid is equal to the pressure on the surface of the liquid. What is the boiling point of propanone if the pressure on its surface is 48 kilopascals?
(1) 25°C
(2) 30°C
(3) 35°C
(4) 40°C / Explanation
That means the boiling point is 35oC à Table H
5. Which solution has the lowest freezing point?
(1) 10 g of KI dissolved in 100 g of water
(2) 20 g of KI dissolved in 200 g of water
(3) 30 g of KI dissolved in 100 g of water
(4) 40 g of KI dissolved in 200 g of water / Explanation
30g per 100gà more particles
40g per 200g is actually 20g per 100g
6. Which barium salt is insoluble in water?
(1) BaCO3
(2) BaCl2
(3) Ba(ClO4)2
(4) Ba(NO3)2 / Explanation
According to Table Fà anything bonded to CO3- will be insoluble (except NH4+ and Group 1 elements)
7. According to Reference Table G, which solution is saturated at 30°C?
(1). 12 grams of KClO3 in 100 grams of water
(2). 12 grams of KClO3 in 200 grams of water
(3.) 30 grams of NaCl in 100 grams of water
(4.) 30 grams of NaCl in 200 grams of water / Explanation
It is on the line when 12g are added (per 100g of H2O)
8. A student prepared four aqueous solutions, each with a different solute. The mass of each dissolved solute is shown in the table below.
Which solution is saturated?
(1) 1
(2) 2
(3) 3
(4) 4 / Explanation
Substance / On the Line / S, US, SS
KI / 145 / At 120à US
NaNO3 / 88 / At 88 à S
KCl / 32 / At 25 à US
KClO3 / 8 / At 5 à US
9. A 10.0-gram sample of which element has the smallest volume at STP?
(1) aluminum
(2) magnesium
(3) titanium
(4) zinc / Explanation
Formula: D = Mass/Volume
Element / Density
Al / 2.698
Mg / 1.738
Ti / 4.540
Zn / 7.133
2.698 = 10/v
1.738 = 10/v
4.54= 10/v
7.133 = 10/v
10. Under which conditions are gases most soluble in water?
(1) high pressure and high temperature
(2) high pressure and low temperature
(3) low pressure and high temperature
(4) low pressure and low temperature / Explanation
Cold coke has more bubbles than warm coke, so low temp.
If pressure is low (like opening a can or bottle) the gas escapes
11. At which temperature is the vapor pressure of ethanol equal to the vapor pressure of propanone at 35 degrees Celsius?
(1) 35°C
(2) 60°C
(3) 82°C
(4) 95°C / Explanation
TABLE Hà At 35oC Propanone has at VP of about 50.
Ethanol has VP of about 50 at about 60oC.
12. A rigid cylinder with a movable piston contains a 2.0-liter sample of neon gas at STP. What is the volume of this sample when its temperature is increased to 30°C while its pressure is decreased to 90 kilopascals?
(1) 2.5 L
(2) 2.0 L
(3) 1.6 L
(4) 0.22 L / Explanation
PV = PV
T T
(101.3kPa)(2L) = (90kPa)(x)
273K 243K
X = 2
13. In which compound is the ratio of metal ions to nonmetal ions 1 to 2?
(1) calcium bromide
(2) calcium oxide
(3) calcium phosphide
(4) calcium sulfide / Explanation
Ca+2 bonds with Br-1 to form CaBr2 à that is one Ca (metal) to two Br (nonmetal)
14. Ionic solids will most likely dissolve in
(1) H2O(l), which is a polar solvent
(2) H2O(l), which is a nonpolar solvent
(3) CCl4 which is a polar solid
(4) CCl4, which is a nonpolar solvent / Explanation
Ionicà transfer electrons, so it is POLAR
Like dissolves like
15. A solution contains 35 grams of KNO3 dissolved in 100 grams of water at 40°C. How much more KNO3 would have to be added to make it a saturated solution?
(1) 29 g
(2) 24 g
(3) 12 g
(4) 4 g / Explanation
The solution is saturate at about 65g.Since we are at 35g we have to add:
65g-35 = 30g
The answer that is closest to 30g is (1)29g.
16. A student want to prepare a 1.0-liter solution of a specific molarity. The student determines that the mass of the solute needs to be 30. grams. What is the proper procedure to follow?
(1) Add 30 g of solute to 1.0 L of solvent.
(2) Add 30 g of solute to 970 mL of solvent to make 1.0 L of solution.
(3) Add 1000 g of solvent to 30 g of solute.
(4) Add enough solvent to 30 g of solute to make 1.0 L of solution. / Explanation
The TOTAL solution must be 1L (30g of solute makes up a little part of that).
(Regents Exam, August 2005)
Part B
Directions: Base your answers to questions 17 through 19 on the information below (4 points).
An unsaturated solution is made by completely dissolving 20.0 grams of NaNO3 in 100.0 grams of water at 20.0°C.
17. Show a correct numerical setup for calculating the number of moles of NaNO3 (gram-formula mass = 85.0 grams per mole) used to make this unsaturated solution.
Formula: From TABLE Tà Total Mass/Gram-Formula Mass = 85/85 = 1 mole
Total Mass: Mass Na= 23
N = 14
O = 16 x 3 = 48
TOTAL = 85g
18. Determine the minimum mass of NaNO3 that must be added to this unsaturated solution to make a saturated solution at 20.0°C.
Since we have 85g, and the solution is saturated at 88g, we have to add about 3g of NaNO3
19. Identify one process that can be used to recover the NaNO3 from the unsaturated solution.
Filtration
Directions: Base your answer to questions 20 through 21 on the information below (3 points).
A light bulb contains argon gas at a temperature of 295 K and at a pressure of 75 kilopascals. The light bulb is switched on, and after 30 minutes its temperature is 418 K.
20. Show a correct numerical setup for calculating the pressure of the gas inside the light bulb at 418 K. Assume the volume of the light bulb remains constant.
P1= 75kPa P2= x (75kPa) = (x)
T1= 295K T2 = 418K (295K) (418K)
V1= constant V2= constant (0.25423 )(418K) = x à 106 kPa
21. What Celsius temperature is equal to 418 K?
418-273 = 145=oC
22. Explain, in terms of collision theory, why an increase in temperature increases the rate of a chemical reaction.(1 point)
An increase of temperature will cause more collisions among particles, increasing the chance of the particles reacting.
23. A liquid boils when the vapor pressure of the liquid equals the atmospheric pressure of the surface of the liquid. Using Reference Table H, determine the boiling point of water when the atmospheric pressure is 90 kPa. (1 point)
The boiling point of water, therefore, is about 97oC.
Directions: Base your answers to questions 24 through 26 on the information below (3 points):
24. What information on the graph indicates that the system was initially at equilibrium?
The rate is constant (it is constant because the lines are FLAT)
25. Explain, in terms of LeChatelier’s principle, why the final concentration of NH3 is greater than the initial concentration of NH3.
The final concentration of NH3 is greater than the initial concentration of NH3 since more product was produced after the addition of H2.
26. Explain, in terms of collision theory, why the concentration of H2(g) begins to decrease immediately after more H2(g) is added to the system.
The concentration begins to decrease since H2is reacting with N2 to produce NH3 in order to reestablish the equilibrium
Directions: Base your answers to question 27 through 29 on the information below (4 points).
27. Express the initial volume of the helium gas sample, in liters.
125.0mL = 0.125L (TABLE C)
28. The piston is pushed further into the cylinder. Show a correct numerical setup for calculating the volume of the helium gas that is anticipated when the reading on the pressure gauge is 1.5 atmospheres. The temperature of the helium gas remains constant.
P1= 1.0atm P2= 1.5atm (1atm)(125mL) = (1.5atm)(x)
T1= 20+273=293K T2 = 293K
(V1= 125mL V2= x (125)/(1.5) = x à 83.mL
29. Helium gas is removed from the cylinder and a sample of nitrogen gas, N2(g) is added to the cylinder. The nitrogen gas has a volume of 125.0 milliliters and a pressure of 1.0 atmosphere at 20.0 °C. Compare the number of particles in this nitrogen gas sample to the number of particles in the original helium gas sample.
Since the volume, temperature and pressure of the helium gas is the same as that of the nitrogen gas, the number of particles is the same for both.