Module 08: Solutions

Question 1

08.01 Properties of Water

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08.01

Properties of Water

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Question 2

08.01 Properties of Water

What properties of water make it essential to life on earth?

Answer 2

Water has a high specific heat capacity allows maintain stable temperature

• Water and Ice: water takes longer most substances to freeze
  
  • less dense than liquid water - floats
  • Ince forms on lakes and rivier on top of water
    
    • organisms in water below
• Perfect Temperatures: water have stable and warm temperatures
  
  • large bodies of water have greater temperature changes between summer and winter months
• Climate Regulator: oceans redistribute heat from solar radiations

Question 3

08.01 Properties of Water

How does polarity affect the cohesive porperty of water?

Answer 3

Water is polar molecule with strong attraction to other water molecules

• causes water to form hydrogen bonds (O-H): strong
• negative oxygen end and its positive hydrogen end, it acts like a magnet and attracts other molecules around it.
• results surface tension → property of liquids caused by attraction between molecules, less penetrable by solid objects

Question 4

08.01 Properties of Water

How does the cohension of water and hydrogen bonding affect specific heat capacity?

Answer 4

Cohension: molecules sticking together and being mutually attracted to one another

• more energy break hydrogen bonds
  
  • once broken: molecules collide and shift into another state of matter
• useful to life on earth: Capillary Action

Question 5

08.01 Properties of Water

What is Capillary Action?

Answer 5

Ability of a liquid to flow in narrow spaces against external forces (like gravity)

Question 6

08.01 Properties of Water

What are solvent and solutes?

Answer 6

Solvent: largest amount

Solute: other

Question 7

08.01 Properties of Water

What is an aqueous solution?

Answer 7

solutions in which water is the solvent

Whether or not a material will dissolve in another is dependent on the materials’ attraction for each other. The stronger the attraction between solute and solvent particles, the greater the ability for them to mix and dissolve. If a solute can dissolve in a solvent like water, it does so because the attractive forces between the solute and solvent are as strong as, or stronger than, the intermolecular forces between the solute particles and solvent particles individually.

In the case of water, the attraction to another substance like sodium (NaCl) has to be stronger than the hydrogen bonds that form between water molecules.

Question 8

08.01 Properties of Water

What is a saturated and unsaturated solution?

Answer 8

containing the maximum amount of solute able to be dissolved under the given conditions

Saturation point = dynamic equilibrium

• A solution that has not reached the point of saturation and equilibrium, meaning that more solute can still be added and dissolved, is called an unsaturated solution.
• not dissolved in solvent = insoluble

Question 9

08.01 Properties of Water

What 4 factors afffect the solubility of a solute?

Answer 9

1. Surface Area
2. Stirring
3. Temperature
4. Pressure

Question 10

08.01 Properties of Water

how does surface area affect solubility?

Answer 10

The greater the number of collisions between the solvent and solute particles, the faster the solute will separate and dissolve in the solvent.

Hence, greater surface area = more collisions

Question 11

08.01 Properties of Water

how does stirring affect solubility?

Answer 11

Increases the rate at which it dissolves in liquid

• disperses dissolved solute particles - continue dissolve
• Rate dissolving increased

Question 12

08.01 Properties of Water

How does temperature affect solubility?

Answer 12

Changing temperature is the only factor that changes both the rate of dissolving and the amount of solute able to be dissolved (solubility).

Dissolving a Solid:

• heat increases rate of dissolving and amount of solute can be dissolved
• increased kinetic energy cuases more movement and more collisions

Dissolving a Gas:

• opposite of solids
• Decreases when heat increases
• increaed temperature = more movement = gas encounters surface more frequentyly = escpaing

Question 14

08.02 Molarity and Dilutions

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08.02

Molarity and Dilutions

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Question 15

08.02 Molarity and Dilutions

What are the units of concentration?

Answer 15

Molarity and percent by mass

• Molarity:

the number of moles of solute in one liter of solution

• Percent by mass:

the number of grams of solute in 100 grams of solution

Question 16

08.02 Molarity and Dilutions

What is molarity as a unit of concentration?

Answer 16

Molarity (M) = (moles of solute (mol)) ÷ (liters of solution (L))

concentration expressed in moles of solute per one liter of solution

Question 17

08.02 Molarity and Dilutions

What is percent of mass?

Answer 17

Concentration of a solution used in everyday life

• mass of the solute, in grams, would be if we had 100 grams of a solution
• Percent by Mass = ^{[mass of solute (g)]} ÷ _{[mass of solute + mass of solvent (g)]} *100

Question 18

08.02 Molarity and Dilutions

How do you complete stoichiometric calculations using the concentration of a solution?

Answer 18

1. What do you know
2. What do you need
3. Start Stoichiometry calculations
4. Use mole ratio from the balanced equation
5. Use molarity in the stoichiometry calculations
6. Convert to desired units and solve.

Question 19

08.02 Molarity and Dilutions

What is dilution?

Answer 19

decrease the concentration of a solution by adding additional solvent

• start with amount of solute →add solvent → until get concentration needed

Question 20

08.02 Molarity and Dilutions

What is the dilution process?

Answer 20

1. A volume containing the desired moles of solute is measured from a stock solution of known concentration.
2. The measured volume of stock solution is transferred to a second volumetric flask.
3. The measured volume in the second flask is then diluted with solvent up to the volumetric mark.

Question 21

08.02 Molarity and Dilutions

What is the dilused solution equation?

Answer 21

M_sV_s = M_dV_d

Ms = the molarity of stock solution

Vs = the volume of stock solution

Md = the molarity of the diluted solution

Vd = the volume of the diluted solution

Question 22

08.02 Molarity and Dilutions

What is true of an aqueous solution that is 15.0 percent HNO3 by mass? (3 points)

1. It contains 15.0 grams of HNO3 per 1.0 liter of water.
2. It contains 15.0 grams of HNO3 per 100 grams of solution.
3. It contains 15.0 moles of HNO3 per 100 moles of water.
4. It contains 15.0 moles of HNO3 per 1.0 liter of solution.

Answer 22

2. It contains 15.0 grams of HNO3 per 100 grams of solution

Question 23

08.02 Molarity and Dilutions

A 650.0 mL solution contains 125 grams of glucose (C6H12O6). If the molar mass of C6H12O6 is 180.16 g/mol, what is the molarity of this solution? (3 points)

1. 0.0106 M C6H12O6
2. 0.0195 M C6H12O6
3. 1.07 M C6H12O6
4. 1.92 M C6H12O6

Answer 23

3. 1.07 M C6H12O6

Question 24

08.02 Molarity and Dilutions

What volume of 0.550 M KBr solution can you make from 100.0 mL of 2.50 M KBr? (3 points)

1. 455 mL
2. 576 mL
3. 924 mL
4. 1,230 mL

Answer 24

1. 455 mL

Question 25

# 08.02 Molarity and Dilutions Which statement is correct about molarity and volume? (3 points) 1. They are directly related. 2. They are inversely related. 3. They are different units of dilution. 4. They are different units of concentration.

Answer 25

**2.** They are inversely related

Question 26

# 08.02 Molarity and Dilutions A 0.680 M Ca(OH)2 solution was prepared by dissolving 55.0 grams of Ca(OH)2 in enough water. What is the total volume of the solution formed? (4 points) 1. 1.09 liters 2. 1.23 liters 3. 2.01 liters 4. 2.18 liters

Answer 26

**1.** 1.09 liters

Question 27

What is the percentage by mass of the solution formed when 22.0 grams of HCl is dissolved in 90.0 grams of water? (4 points) 1. 24.4% 2. 22.48% 3. 19.6% 4. 16.7%

Answer 27

**3.** 19.6%

Question 28

# 08.04 Acids and Bases ♣ 08.04 Acids and Bases ♣

Question 29

# 08.04 Acids and Bases What are everyday acids?

Answer 29

* Yogurt (lactic acid) * Leafy vegetables (ascorbic acid) * Orange juice (citric acid) * Tea (tannic acid) * Sodas (carbonic acid) * Wine (tartaric acid) * Vinegar (acetic acid) * Stomach fluid (gastric acid)

Question 30

# 08.04 Acids and Bases What are everyday bases?

Answer 30

* Detergents * Soaps * Ammonia * Window cleaners * Fertilizers * Toothpaste * Antacids

Question 31

# 08.04 Acids and Bases What is **Svante Arrhenius**'s definition of acid and bases?

Answer 31

**Acids**: * acid is a compound that contains element hydrogen * increases hydrogen ions (H+) when dissolve in a solution * acid *_donates_* the hydrogen ion **Base (or alkaline):** * compound that has the elements oxygen and hydrogen (form of hydroxide) * Hydroxide ions (OH-) increases when a base is dissolved in a solution * base *_receives_* the hydrogen ion

Question 32

# 08.04 Acids and Bases What happens when polar water molecules have a hydrogen ions added and removed?

Answer 32

* Removed one+ hydrogen ion: acidic molecule (HCL) leaving behind a negative ion (CL-) * positive hydrogen ions from acidic substance bond to water = hydronium ions * acid donates ions

Question 33

# 08.04 Acids and Bases What are the differences beteween the physical and chemical properties of acids?

Answer 33

Acids * Sour taste * Corrosive (burn your skin and break down other materials) * Increase the concentration of H+ when added to water * Dissolve metals * Donate a hydrogen ion

Question 34

# 08.04 Acids and Bases What are the differences beteween the physical and chemical properties of bases?

Answer 34

* Bitter taste * Slippery feel * Increase the concentration of OH− when added to water * Caustic (react violently with strong acids) * Receive a hydrogen ion

Question 35

# 08.04 Acids and Bases What is "pH?"

Answer 35

**A compound's pH is a number used to specify how acidic or basic it is when dissolved in water.**

Question 36

# 08.04 Acids and Bases What are strong acids and bases?

Answer 36

*Ionize close to 100 percent in an aqueous solution* * concentration indicates the concentration of: * hydroxide ions for bases * hydronium ions for acids **Strong Acids:** * strong electrolytes (liquid contains ions and decomposable by electrolysis) * because of greater concentration of ions * example: metal hydroxides

Question 37

# 08.04 Acids and Bases What are weak acids and bases?

Answer 37

*Very in their degree of ionization in an aqueous solution* * often less than 50% * Weak acids: weak eletrolytes (fewer ions in solution at a given time concentration) * not indicate concentration of hydrogen or hydronium ions in the solution.

Question 38

# 08.04 Acids and Bases What are neutralization reactions?

Answer 38

* acid and base come together * react to **neutralize (reduce) acidic and basic properties** of a reaction * double replacement reaction (produces water and salt) * occur without water or hydroxide ions

Question 39

# 08.01 Properties of Water Frozen water is less dense than liquid water, allowing lake organisms to survive winter. (3 points) True False

Answer 39

True

Question 40

# 08.01 Properties of Water Which of the following is not a property of water? (3 points) 1. Hydrogen bonding causes a high surface tension. 2. Hydrogen bonds exist only in the solid state. 3. Water can dissolve ionic and polar molecules. 4. Water's solid state is less dense than its liquid state.

Answer 40

**2.** Hydrogen bonds exist only in the solid state

Question 41

# 08.01 Properties of Water Which of the following changes would decrease the rate at which a solid solute dissolves in a liquid solvent? (3 points) 1. Decreasing pressure 2. Decreasing surface area 3. Increasing rate of stirring 4. Increasing temperature

Answer 41

**2.** Decreasing surface area

Question 42

# 08.01 Properties of Water Why can ionic table salt and covalent rubbing alcohol both dissolve in water? (3 points) 1. Alcohol's polar bonds and salt's ions have higher potential energy than the potential energy of the hydrogen bonding between water molecules. 2. Alcohol's polar bonds and salt's ions are both able to form strong attractions to the polar water molecules. 3. The temperature of liquid water is high enough to allow anything to mix well with its fast-moving molecules. 4. The air pressure above the water is greater than the pressure exerted by the moving water molecules.

Answer 42

**2.** Alcohol's polar bonds and salt's ions are both able to form strong attractions to the polar water molecules

Question 43

# 08.01 Properties of Water Which of the following describes an impact of the specific heat of water on the planet and the life forms that exist on it? (3 points) 1. Places near the sea show high temperature variation. 2. Inland cities have moderate temperatures throughout the year. 3. Marine life experiences sudden spikes and drops in temperature. 4. Sweat requires a lot of thermal energy to be absorbed to evaporate.

Answer 43

**4.** Sweat requires a lot of thermal energy to be absorbed to evaporate

Question 44

# 08.01 Properties of Water Explain how the cohesive and adhesive properties of water are useful in maintaining various life processes. (5 points)

Answer 44

Cohesion refers to water's ability to stick to itself, and adhesion refers to water's ability to stick to other services. Water can do this due to its high surface tension. These properties allow water to travel from the roots to the leaves of plants, allowing the plant to absorb the nutrients. Similarly, cohesion allows some plants to float on water rather than sinking to the bottom. Hence, plants like water lilies can float on top of lakes, absorb sunlight and carbon while gathering water from their roots.

Question 45

# 08.01 Properties of Water Which of the following is a correct statement about water? (3 points) 1. Hydrogen bonding causes water to be strongly cohesive. 2. Hydrogen bonding causes water to have a low surface tension. 3. Water is a universal solvent because polar and nonpolar solutes can dissolve in it. 4. Water is less dense as a liquid than as a solid because of changes in bond structure.

Answer 45

**3.** Water is a universal solvent because polar and nonpolar solutes can dissolve in it

Question 46

# 08.01 Properties of Water Which of the following changes would decrease the rate at which a solid solute dissolves in a liquid solvent? (3 points) 1. Decreasing pressure 2. Decreasing surface area 3. Increasing rate of stirring 4. Increasing temperature

Answer 46

2. Decreasing surface area

Question 47

Explain how the solubility of water is useful in maintaining various life processes. (5 points)

Answer 47

Because water is a "universal solvent," aqueous solutions are an invaluable life-sustaining force. Water allows humans to digest food by breaking the chemical bonds between carbohydrates, proteins, and fats. Furthermore, it extracts the energy humans need for life during cellular respiration. The cohesion of water molecules helps humans and other life forms regulate their body temperature and help blood carry molecules to necessary locations. CLOSE

Question 48

# 08.05 Acid and Base Calculations ♣ 08.05 Acid and Base Calculations ♣

Question 49

# 08.05 Acid and Base Calculations What are amphoteric substances?

Answer 49

*A substance that acts as an acid or a base by both receiving and donating hydrogen ions*

Question 50

# 08.05 Acid and Base Calculations How does water react with other samples of pure water?

Answer 50

One water molecule, acting as an acid, donates a hydrogen ion to another water molecule, acting as a base. * This reaction forms hydroxide and hydronium ions, * can also react together to re-form the water molecules. * Water has an ionization constant to represent the number of hydronium and hydroxide

Question 51

# 08.05 Acid and Base Calculations Wht is the Ionization Constant of Water?

Answer 51

**[H₃O⁺] × [OH⁻] = 1.0 × 10⁻¹⁴ M**

Question 52

# 08.05 Acid and Base Calculations How do acids and bases affect the concentration of a solution?

Answer 52

* **Acid** increases concentration of hydronium ions * **Bases** decreases concentration of hydronium ions

Question 53

# 08.05 Acid and Base Calculations How does the pH scale reflect the concentration of hydronium or hydroxide?

Answer 53

**Basic**: *OH⁻ \> H₃O⁺* * concentration of hydroxide is greater than concentration of hydronium ions * adding base: increases hydronium ions present **Neutral**: * OH⁻ = H₃O⁺* * When the concentrations of the hydronium and hydroxide ions are equal, the solution is neutral. **Acidic**: *OH⁻ \< H₃O⁺* * the concentration of hydronium ions is greater than the concentration of hydroxide ions * Adding an acid, such as hydrochloric acid, to pure water will increase the concentration of hydronium ions present.

Question 54

# 08.05 Acid and Base Calculations What is the pH scale?

Answer 54

The pH scale is a numeric scale used to indicate the _hydronium ion concentration_ of a solution * values dependent temperature * invese relationship between pH value hydronium concentration * determined calculating negative base-10 logarithm of the hydronium ion concentration (molarity)

Question 55

# 08.05 Acid and Base Calculations What is the pH value of a solution?

Answer 55

**pH = −log⁡[H₃O⁺]** or **pOH = −log[OH⁻]** The relationship between pH and pOH of a solution can be expressed as: _pH + pOH = 14_

Question 56

# 08.05 Acid and Base Calculations How can the pH be used to find the hydronium and hydroxide concentration?

Answer 56

**[H₃O⁺] = 10−pH** or **[OH⁻] = 10^−pOH**

Question 57

# 08.05 Acid and Base Calculations Acids increase the concentration of hydronium ions in solution by donating hydrogen ions to water molecules. (2 points) True False

Answer 57

True

Question 58

# 08.05 Acid and Base Calculations A solution at 25 degrees Celsius has a pH of 4.48. What is the pOH of this solution? (4 points) 1. 0.978 2. 3.17 3. 9.52 4. 10.51

Answer 58

**3.** 9.52

Question 59

# 08.05 Acid and Base Calculations What is the pH of a solution with a concentration of 5.2 × 10⁻⁸ M H₃O+? (4 points) 1. 1.01 2. 3.24 3. 7.28 4. 8.72

Answer 59

**3.** 7.28

Question 60

# 08.05 Acid and Base Calculations What are the concentrations of hydroxide and hydronium ions in a solution with a pH of 10.2? (4 points) 1. 1.4 × 10⁻⁴ M H3O+ and 7.1 × 10⁻¹¹ M OH− 2. 3.8 × 10⁻⁶ M H3O+ and 2.6 × 10⁻⁹ M OH− 3. 8.3 × 10⁻⁹ M H3O+ and 1.2 × 10⁻⁶ M OH− 4. 6.3 × 10⁻¹¹ M H3O+ and 1.6 × 10⁻⁴ M OH−

Answer 60

**4.** 6.3 × 10⁻¹¹ M H3O+ and 1.6 × 10⁻⁴ M OH−

Question 61

# 08.05 Acid and Base Calculations What is the pH of a solution with a 2.20 × 10⁻⁸ M hydroxide ion concentration? (4 points) 1. 0.342 2. 6.00 3. 6.34 4. 7.66

Answer 61

**3.** 6.34

Question 62

# 08.05 Acid and Base Calculations The concentration of hydroxide ions is greater than the concentration of hydronium ions for acidic solutions. (2 points) True False

Answer 62

False

Question 63

# 08.05 Acid and Base Calculations A solution at 25 degrees Celsius has a pOH of 6.42. What is the pH of this solution? (4 points) 1. 0.842 2. 3.80 3. 5.59 4. 7.58

Answer 63

**4.** 7.58

Question 64

# 08.05 Acid and Base Calculations What is the pH of a solution with a concentration of 7.6 × 10⁻⁷ M H3O+? (4 points) 1. 0.993 2. 6.12 3. 7.88 4. 8.34v

Answer 64

**2.** 6.12

Question 65

What are the concentrations of hydroxide and hydronium ions in a solution with a pH of 8.3? (4 points) 1. 2.9 × 10−5 M H3O+ and 3.4 × 10−10 M OH− 2. 3.1 × 10−6 M H3O+ and 3.2 × 10−9 M OH− 3. 5.0 × 10−9 M H3O+ and 2.0 × 10−6 M OH− 4. 6.3 × 10−11 M H3O+ and 1.6 × 10−4 M OH−

Answer 65

**3.** 5.0 × 10−9 M H3O+ and 2.0 × 10−6 M OH−

Question 66

# 08.06 Honors Environmental Impact ♣ 08.06 Honors Environmental Impact ♣

Question 67

# 08.06 Honors Environmental Impact What are renewable resources?

Answer 67

**natural resource that is replaceable through biogeochemical cycles or sustainable practices** * _Abiotic Factors_: (water, sunlight, wind) not associated with or derived from living organisms * _Biotic Factors_: (forests, wildlife) factors in an environment relating to, caused by, or produced by living organisms

Question 68

# 08.06 Honors Environmental Impact What is nuclear power?

Answer 68

* **clean** → not pollute air but there are radioactive byproducts * Disposal: * near-surface disposal * caverns below ground radioactive wastes are isolated by engineered and geological barriers that prevent the radiation from reaching humans, their groundwater, and the environment

Question 69

# 08.06 Honors Environmental Impact What is natural gas?

Answer 69

* Greenhouse gasses & transported pipeline or takers (pollution and heath risks) * New discoveries and new extraction, storage, and transport methods have led to a rise in shale gas, liquified natural gas (LNG), and methane hydrate gas use in North America * _Shale Gas_: recently developed the ability to reach these stores economically * _Methane Gas_: natural gas trapped in arctic ice or beneath the ocean floor

Question 70

# 08.06 Honors Environmental Impact What is hydropower?

Answer 70

*Water falls through openings in a dam or river current* * no carbon-based pollution or harmful chamicals * large dams: alter natural flow can intervene seasonal fish migraiont * developing marine and hydrokinetic energy technologies that convert the energy of waves, tides, and ocean currents into electricity

Question 71

# 08.06 Honors Environmental Impact What is biofuel?

Answer 71

Biofuel, or biomass, includes wood, garbage, animal dung, and agricultural waste, such as corncobs and wheat straw * use of garbage and agricultural waste while reducing our dependence on fossil fuels * make enough fuel to replace the need for nonrenewable resources, a large amount of land would be needed to grow the agricultural materials * still produces pollutants and carbon dioxide like the burning of fossil fuels

Question 72

What is geothermal power?

Answer 72

* operate virtually emission- and pollution-free if they are constructed and operated correctly * less land than other power generation technologies and without the miles of buried pipelines * **very expensive** to build and can be built only in areas with the correct geology