Chemistry Semester 2 Final exam

To increase the solubility of a gas at constant temperature and 202 kPa pressure from 0.85 g/L to 5.1 g/L, the pressure would have to be increased to:

1212 kPa.

How many milliliters of alcohol are in 167 mL of an 85.0% (v/v) alcohol solution?

142 mL

What is the percent (m/m) of a water solution that contains 60 g of calcium chloride, CaCl2, and that has a mass of 400 g?

15%

How many water molecules are in two formula units of barium hydroxide octahydrate, Ba(OH)2 • 8H2O?

16

How many mL of alcohol are in 240 mL of 95.0% (v/v) alcohol solution?

228 mL

What is the molarity of a solution that contains 8 moles of solute in 2 L of solution?

4M

What is the pH of a solution in which [OH-] = 1 × 10−5?

9.0

A water molecule is best represented by

A

Identify the Brønsted-Lowry base and conjugate base in this reaction. (H2S + H2O ---> H3O+ + HS-)

HS- and H2O

Which of the following operations usually makes a substance dissolve faster in a solvent?

all of the above

A solution in which the hydroxide-ion concentration is 1 × 10-5M is

basic

A solution in which the hydroxide-ion concentration is 1 × 10−2 is

basic

Which of the following is not an electrolyte

cane sugar(aq)

Gelatin would best be classed as:

colloidal dispersion

If the pressure of a gas above a liquid is decreased (at constant temperature), the solubility of the gas in the liquid:

decreases

At a given temperature, the solubility of a gas in a liquid is:

directly proportional to the pressure of the gas above the liquid.

In a neutral solution, the [H+] is

equal to [OH-]

A solution is a mixture

from which the solute cannot be filtered

A typical kind of emulsion is:

mayonnaise

Which of the following mixtures DO NOT exhibit the Tyndall effect?

solutions

If the addition of a crystal to an aqueous solution causes a great deal of dissolved solid to come out of solution, the original solution was

supersaturated.

Surface tension is

the inward force that tends to minimize the surface area of a liquid

If more solvent is added to a solution:

the molarity decreases

Colligative properties depend on:

the number of particles dissolved in a given mass of solvent

An ionic compound has a solubility of 30 g per 100 mL of water at room temperature. A solution containing 70 g of the compound in 250 mL of water at the same temperature is:

unsaturated

The formula of the hydrogen ion is often written as

H+

If the [H+] in a solution is 1 × 10−3 mol/L, then the [OH-] is

1 × 10−11 mol/L

To 225 mL of a 0.80M solution of KI, a student adds enough water to make 1 L of a more dilute KI solution. What is the molarity of the new solution?

0.18M

The reaction that takes place when an acid is added to an ethanoic acid-ethanoate (CH3COOH/CH3COO-) buffer is

CH3COO- + H --> CH3COOH

Increasing the temperature of a liquid-solid solution will:

Both a and b... always increase the rate at which a crystalline solute dissolves. + often increase the amount of crystalline solute that dissolves.

In the reaction... (CO3^2- + H2O--> HCO3- + OH-) the carbonate ion is acting as a(n)

Brønsted-Lowry base.

Which of these would you expect to be soluble in the nonpolar solvent carbon disulfide, CS2?

CBr4

43. What is the percent by mass of water in the hydrate CoCl2 • 6H2O?

Molar Mass of Hydrate = 129.83g + 108.02g = 237.85 g (total molar mass for the CoCl2 and 6H2O) 1 mol of H2O = 18.02 g so 6 mol H2O = 6(18.02 g) = 108.02 g Divide 108.02 g /237.85 g x 100 = 45.41% H2O

Which salt hydrolyzes water to form a solution that is acidic?

NH4Br

Which of the following is an example of a strong electrolyte?

NaCl

42. A gas has a solubility in water of 16.9 g/L at 15°C and 505 kPa of pressure. What is its solubility in water at 15°C and 606 kPa of pressure?

S1/P1 = S2 /P2 Plug the known values into the equation and solve for the unknown.

An electric current is conducted by

a solution of NaCl

Possible Essay Questions: Please use the attached rubric to answer the following questions. 45. 10 points a) Describe the process of solvation of ionic solids in water. b) Using at least two of the concepts presented in this chapter, explain how soaps and detergents work in removing oil and grease from clothing. c) Compare and contrast the properties of acids and bases...use real world examples in your comparison. d) Distinguish between the Brønsted-Lowry and Lewis theories of acids and bases.

a) Because polar water molecules can attract charged particles, they cause solute ions to break away from the surface of the solid. As the solute dissolves, the ions are surrounded by molecules of solvent. b) Soaps and detergents are surfactants that reduce the surface tension of water by interfering with the hydrogen bonding between water molecules. With surface tension reduced, the beads of water that would normally have formed collapse, allowing the water to spread out to cover and penetrate the fabric. Soaps and detergents also are emulsifying agents that allow oils and greases to form colloidal dispersions. The oil and grease particles which are normally insoluble in water are removed from the surface of the fabric. c) Both acids and bases cause indicators to change colors and react with each other to form water and a salt. Acids taste sour, turn blue litmus red and are electrolytes, ex: citrus juices, pickles, sodas; Bases taste bitter and/or salty, turn red litmus blue, and are electrolytes, ex: bleach, baking soda, drain cleaner d) The Bronsted-Lowry theory defines acids as proton donors and bases as proton acceptors. According to the Lewis theory, acids are electron-pair acceptors and bases are electron-pair donors.

BONUS: Write complete and balanced equations for each of the following neutralization reactions: a. HF(aq) + KOH(aq) → b. H2SO4(aq) + 2LiOH(aq) →

a) KF(aq) + H2O(aq) b) 2H2O(l) + Li2SO4(aq)

Write complete and balanced equations for each of the following acid-base reactions. a. 2HBr + Mg(OH)2→ b. 3H2SO4 + 2Al(OH)3→

a) MgBr2 + 2H2O b) Al2(SO4)3 + 6H2O

41 a) Calculate the molarity of a solution prepared by dissolving 95.5 g of KNO3 in enough water to make 750 mL of solution. b) How would you prepare 250 mL of 0.60M Al2(SO4)3 solution from a 2.0M Al2(SO4)3 stock solution?

a)Molarity = moles of solute / L solution Convert g of KNO3 to moles and 750 mL to L then plug into the equation. b)M1V1 = M2V2 Plug the known values into the equation and solve for the unknown.

44. Calculate the pH for the following solutions. State whether each solution is acidic, basic, or neutral. (Use the LOG function)

a. [H+] = 1 × 10-9 M 9, basic b. [OH-] = 1 × 10-10 M 4, acidic c. [H+] = 1 × 10-7 M 7, neutral

The high surface tension of water is due to the

hydrogen bonding between water molecules

The density of ice is less than the density of water because

hydrogen bonding in ice produces an open framework.

The attractions between adjacent water molecules are called

hydrogen bonds

Salts and other compounds that remove moisture from air are said to be

hygroscopic

In general, as the temperature of a solution composed of a gas in a liquid is decreased, the solubility of the gas

increases