UP Chemical Society in partnership with UP 49ers
brings you Chemistry Review Series Chem 16 3rd Long Exam I. Modified True or False. Write TRUE if the statement
is correct. Otherwise, write FALSE then change the underlined word(s) to make the statement true. 1. Gas molecules possess volume but have negligible mass. - This solution is 2. A solution contains 1.8 x 10 -9 M [OH ]. therefore basic. 3. Nuclear binding energy is the energy absorbed when nucleons fuse together into a nucleus. 4. Nuclear reactions, in general, give off much more energy than chemical reactions. 5. The gas constant varies on two components of the Ideal Gas Equation: volume and temperature. 6. Alloys are solutions with a metal solute and liquid solvent. 7. The 7. The pH of a 0.20 solution of HCN (K a = 4.9 x 10 -10 ) is equal to 5. 8. A solution is a homogeneous mixture, and can be described as either dilute, a solution with minimal solute originally, and as concentrated, a solution with the maximum. 9. Generally, an increase in temperature increases the solubility of gases in water. 10. Pressure changes do not affect the solubility of liquids and solids, but affects the solubility of gases as described by Henry ’s ’s Law. 11. Hexane and octane will form an ideal solution, due to their IMFAs being quite similar. 12. Increased moles of H 2 at 300 K and 1 atm results to gas compression. 13. When ice cubes are made by placing water in a tray in a freezer, energy is removed from the water molecules, which gradually slow down. 14. When ethanol is mixed with acetone, this results to a decrease in temperature and an increase in volume of the solution.
4. HBr was added to the gumamela extract instead of HCl.
Color change
5. The water used to dilute pH change as compared 0.1M HCl was contaminated to uncontaminated with some 0.1 0.1 M NaOH water III. Multiple Choice. Write the letter of your your answer.
1. According to the Bronsted-Lowry theory, which of the following is correct (given the chemical equation below): NH3 + H2PO4- NH4+ + HPO42a) NH4- acts as the conjugate base of NH 3 b) In the reverse reaction, H 2PO4- acts as the conjugate acid c) HPO42- acts as the conjugate acid of H2PO4d) In the forward reaction H 2PO4- acts as the conjugate base
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2. Glycerin (C3H8O3 ) ) is a nonvolatile nonvolatile nonelectrolyte with a density of 1.26 g/mL at 25°C. A solution was made by mixing 50.0 mL of glycerin to water (500.0 mL). Calculate the vapor pressure of the solution at 25°C if the vapor pressure of pure water at 25°C is 23.8 torr, and its density is 1.00 g/mL. a) 23.7 torr b) 23.8 torr c) 23.9 torr d) 24.0 torr For numbers 3 and 4, refer to the diagram below: B
II. Cause and Effect. Identify the effect of the condition on the indicated parameter. Write increase, decrease, no effect, or indeterminate. Condition
Parameter
1. 0.8 molal rock salt solution was used instead instead of 0.3 molal.
Boiling point elevation
2. Presence of air bubbles in eudiometer
%error between calculated and pre weighed Mg Mg
3. The volumetric flask used Temperature; Final to mix methanol and water volume of solution wasn’t dry.
A
3. Point T is where ______ a) supercritical fluid is created b) the three phases coexists c) intermediates are formed d)the phases are isolated from each other 4. Supercritical fluid exists in Point __ a) A c) C b) B d) D
5. Which of the following nuclides would you expect to be stable and why? a) 88Sr, because it has an average mass of 87.6 b) 118Cs, because it has an average mass of 132.9 c) 30S, because it has an average mass of 32.1 d) 214Po, because it has an atomic number of 84 6. Given 500 mL of a sucrose solution in 9.88 ppm, calculate the volume (in mL) of the solution in which 0.75 grams of sucrose can be found. a) 0.0821 mL b) 0.0653 mL c) 0.0759 mL d) 0.092 mL
7.
Mo He → Tc _____ a) −e b) +e c) 2 n d) n
8. The average osmotic pressure of blood is 7.7atm at 25°C. What molarity of glucose (C 6H12O6 ) will be isotonic with blood? Note that glucose is a nonelectrolyte. a) 0.30 M b) 0.31 M c) 0.32 M d) 0.43 M 9. The following are the formulas of the gas laws. Identify the incorrect equation: a) Boyle’s Law: b) Charles’s Law:
= = c) Avogadro’s Law: = d) Ideal Gas Equation: =
10. Which of the following is true? a) Absorption of an electron by the nucleus is followed by X radiation. b) Atomic number decreases by 4 upon emission of alpha particle. c) Atomic number decreases by 4 upon emission of alpha particle. d) Beta decay involving conversion of a proton to a neutron inside the nucleus emits β - particle. 11. Silver nitrate, AgNO 3, reacts with sodium chloride as indicated by the following equation. What mass of NaCl would be required to react with 200 mL of 0.200 M AgNO 3 solution? AgNO3 + NaCl → AgCl + NaNO3 a) 0.117 g b) 1.17 g c) 2.34 g d) 4.68 g
12. Given the following acids and corresponding pK a, what would be the most basic (strongest) conjugate base? D Acid pK a H2O 15.7 CH3CH2OH 16 (CH3 )3COH 18 CH3COCH3 19.2 a) HOb) CH3CH2Oc) (CH3 )3COd) -CH2COCH3 13. What is the van’t Hoff factor of a 0.10 m HF(aq) solution with a freezing point depression of – 0.2010C? (K f = 1.86 0C/m) a) 1.07 b) -1.07 c) 1.08 d) -1.08 14. Dissolution of carbon dioxide in water yields a) solution with separate gaseous and liquid phases. b) solution that can change red to blue litmus paper. c) solution of pH less than 7. d) none because CO2 cannot be dissolved in water. IV. Problem Solving.
1. Container X holds 5.35 grams of He, in a volume of 20.2 L. Container Y holds 8.66 grams of H 2, in its volume of 25.0 L. Lastly, container Z holds 0.45 moles of gas AlDub, in a 15.7 L volume. Calculate for (a) partial pressures of each gas, (b) the total pressure if Containers X and Y are added, and (c) the molar mass of gas AlDub if its density is 1.45 g/L. 2. Madame Curie won the 1911 Nobel Prize for isolating radium. Radium-226 has a half-life of 1662 years and undergoes alpha decay. a) Write the equation for the decay process. b) If she had 1.20 g of Radium-226 in her lab in 1911, what would be its mass in 2010? 3. A sucrose-water solution is produced by dissolving 2.45 grams of sucrose in water to produce a 75-mL solution with density 0.584 g/mL. (MW sucrose = 342.3 g) Calculate for the mass-volume percent, molarity, and molality. 4. How many milliliters of 12 M hydrochloric acid solution necessary to consume 80 mg of magnesium metal? Calculate %error if 1.87 mmol Mg was found to have reacted. (MW Mg = 24.3050 g/mol; MW HCl = 36.4606 g/mol) 5. Nyemi prepared a 0.10 M solution of formic acid (HCOOH). When he measured its pH at 25°C, it read as 2.38. What is the K a of the acid at this temperature? What is its percent ionization?
grams sucrose x 100 Mass⁄vol percent= 2.4575mL Mass⁄vol percent=3.27% solution
Answer Key: I. True or False 1. FALSE mass, volume 11.TRUE 2. FALSE acidic 12. FALSE gas expansion 3. FALSE released 13.TRUE 4. TRUE 14. TRUE 5. FALSE volume & pressure 6. FALSE metal solvent 7. TRUE 8. FALSE concentrated, dilute 9. FALSE decreases 10. TRUE
(b) Molarity
moles of solute Molarity= volume ofmol solution 1 2.45 grams x 342.3 g M = 0.075 L solution = 0.0954 M (c) Molality
mL Mass of solution= 75 mL x 0.584 g Mass of solution= 128.42 grams Mass of HO=128.42 g2.45 g Mass of HO=125.97 grams 1 mol 2.45 grams x 342.3 Molality= 0.12597 kg HO g Molality=0.05682 m
II. Cause and Effect
1. Increase 2. Decrease 3. Increase; Increase
4. No effect 5. Increase 6. Increase
III. Multiple Choice
1. B 2. B 3. B 4. C 5. A
6. A 7. C 8. B 9. B 10. A
11. C 12. D 13. C 14. C
4. a. mL HCl:
1 mol Mg 2 mol HCl1 L HCl solution 1000 mL 24.3050 g 1 mol Mg 12 mol HCl 1L
IV. Problem Solving
=0.080g
1. (a) Partial Pressures
= 6.6 mL HCl
PV=nRT 1 mol )0.0821318.15 (5.35 x 4.0026 nRT g P= V = 20.2 P He = 1.728 atm 1 mol )0.0821318.15 (3.66 x 2.016 nRT g P= V = 20.2 P H = 2.348 atm 0.450.0821313.15 P = nRT = V P AlDub=0.573 atm 20.2
(a) Total Pressure of X and Y
1.337 mol 1.8150.0821318.15 P = nRT = 20.2 P = 4.V076 atm
(b) MM of AlDub
1.450.0821313.15 MM = DRT = MM = 65.P 06g⁄mol 0.573 2. a) → b) The half-life decay formula is: A = A × 2 h A = resulting amount after t years Ao = initial amount h = half-life of the substance t = time in years
A=1.20×2−− − A=1.20×2 = .
3. (a) Mass-volume percent
mass of solute x 100 Mass⁄vol percent= volume of solution
3050 g ] .−[.24. x 100 = 43% b. %error = . 5.
