Ch. 8/ Solutions

Question 1

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Solutions
MIXTURES

What is a pure substance?

Answer 1

A pure substance is a substance that is made up of only one type of particle, either atoms or molecules.

Examples include elements like oxygen and compounds like water.

• PURE SUBSTANCES- elements, covalent compounds, and ionic compounds. 📍📍📍

Question 2

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MIXTURES

What is a heterogeneous mixture?

Answer 2

• a heterogeneous mixture does not have a uniform composition throughout the sample

• the composition varies within the mixture, and you can usually see the different substances mixed together.

Examples: salad, sand and water, and oil and water.

Question 3

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MIXTURES

What is a homogenous mixture?

Answer 3

• a homogenous mixture has a uniform composition throughout the sample

• the composition is the same throughout, and it’s difficult to distinguish between the different substances in the mixture.

Example: Salt water and air

Question 4

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MIXTURES
SOLUTIONS

What is a solution and what two parts does it consist of?

Answer 4

• a solution is a homogenous mixture that contains small particles. Liquid solutions are often transparent.

Solutions consist of two parts:

• the solute is the substance present in a lesser amount

• the solvent is the substance in a larger amount

💥An aqueous solution has water as the solvent

Question 5

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MIXTURES
COLLOIDS AND SUSPENSIONS

What is a colloid?

Answer 5

• a colloid is a homogenous mixture with larger particles, often having an opaque appearance.

• Particles in a colloid cannot be filtered from its other components
• They do not settle out

Ex: milk, fog, whipped cream, paint, blood

Question 6

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MIXTURES
COLLOIDS AND SUSPENSIONS

What is a suspension?

Answer 6

• a suspension is a heterogeneous mixture that contains large particles suspended in a liquid.

• Particles are so large that they do not dissolve any liquid
• They can be filtered away from the liquid or separated, using a centrifuge

Ex: salad dressing, orange juice, muddy water,

Question 7

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What is the Tyndall effect?

Pg 8

Answer 7

• Tyndall effect- light is scattered as it travels through a colloid making the light pathway visible

Question 8

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ELECTROLYTES AND NONELECTROLYTES

What is an electrolyte?

Answer 8

An electrolyte is a substance that conducts in electric current in water

NaCl(aq) dissociates into Na+(aq) and Cl^- (aq)

Question 9

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ELECTROLYTES AND NONELECTROLYTES

What is a non-electrolyte

Answer 9

A non-electrolyte is a substance that does not conduct an electric current in water

H2O2 does not dissociate

Question 10

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ELECTROLYTES AND NONELECTROLYTES

What makes a strong electrolyte and what makes a weak electrolyte?

Pg 9 📽️

Answer 10

• a strong electrolyte dissociates completely and water to form ions

• a week electrolyte dissociates partially in water to form some ions, mostly uncharged molecules

Question 11

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Review
ELECTROLYTES AND NONELECTROLYTES

List three solutes, species in solution, conductivity, and examples.

Answer 11

1.
Solute: strong electrolyte
Specifies in Solution: ions
Conductivity: conducts an electric
Examples: NaCl, KOH, HCl, KBr

2.
Solute: week electrolyte
Specifies in Solution: molecules with ions
Conductivity: conducts an electric current
Examples: NH3, CH3CO2H, HF

3.
Solute: non-electrolyte
Specifies in Solution: molecules
Conductivity: does not conduct an electric current
Examples: CH3CH2OH, H2O2

Question 12

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SOLUBILITY GENERAL FEATURES

What is solubility?

Answer 12

• Solubility is the amount of solute that dissolves in a given amount of solvent.

• It is usually reported in grams of solute per 100 mL of solution (g/100mL)

Question 13

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SOLUBILITY GENERAL FEATURES

What is a saturated solution?

Answer 13

A saturated solution contains the maximum number of grams of solute that can dissolve

Question 14

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SOLUBILITY GENERAL FEATURES

What is an unsaturated solution?

Answer 14

An unsaturated solution contains less than the maximum number of grams of solute that can dissolve.

Question 15

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SOLUBILITY
BASIC PRINCIPLES

Solubility can be summed up as “like dissolves like.”

Answer 15

• this is due to the interaction of intermolecular forces
• substances, exhibiting or able to exhibit, the same intermolecular forces will dissolve in one another

✨✨✨”Like dissolves like” refers to the principle that substances with similar chemical properties tend to dissolve in each other. For example, polar solvents like water tend to dissolve polar solutes like salt or sugar, while nonpolar solvents like oil dissolve nonpolar solutes like grease or wax. This principle arises from the idea that molecules with similar polarity or intermolecular forces are more likely to mix and form a solution.

Question 16

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SOLUBILITY
BASIC PRINCIPLES

Solubility can be summed up as “like dissolves like.”

Answer 16

Most ionic and polar covalent compounds are soluble in water, a polar solvent

• they contain dipole interactions, allowing them to mix

• neutral molecules with O or N atoms that can hydrogen bond to water are water soluble

• nonpolar compounds are soluble and nonpolar sulfates (like dissolves like)

• Octane (C8H18) dissolves in CCl4 because both are nonpolar liquids
- both exhibit only London dispersion forces

Question 17

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SOLUBILITY
BASIC PRINCIPLES

When solvation (dissolution) release more energy then that required to separate particles, the overall process is…… ? (Heat is released)

Answer 17

Exothermic

Question 18

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SOLUBILITY
BASIC PRINCIPLES

When the separation of particles requires more energy than is released during solvation, the process is…..? (Heat is absorbed)

Answer 18

Endothermic

Question 19

💥 See Pg 16 for rules of solubility of Ionic compounds
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Question 20

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When do SINGLE REPLACEMENT REACTIONS occur?

See pg 17 for activities series 📝

Answer 20

• single replacement reactions only occur when the element that is doing the replacing is more reactive than the element that is being replaced

Question 21

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EFFECTS OF T AND P
TEMPERATURE (T) EFFECTS

True or False?

1. For most ionic and molecular solids, solubility generally increases as temperature increases.
2. by dissolving a solid in a solvent at a high temperature and allowing it to cool slowly, super saturated solution can be made.
3. The solubility of a gas decreases with increasing temperature.

Answer 21

True
True
True

Question 22

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EFFECTS OF T AND P
TEMPERATURE (T) EFFECTS

What is a supersaturated solution?

Answer 22

• A supersaturated solution contains more than the predicted maximum amount of a solute at a given temperature.

Question 23

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SOLUBILITY– EFFECTS OF T AND P
~PRESSURE (P) EFFECTS

What is Henry’s law?

Pg 20 for image 📽️

Answer 23

• Henry’s Law: the solubility of a gas in a liquid is proportional to the partial pressure of the gas above the liquid.

• the higher the pressure, the higher the solubility of a gas in a solvent

Question 24

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CONCENTRATION UNITS
WEIGHT/ VOLUME PERCENT

What does the concentration of a solution tell us?

Answer 24

• The concentration of a solution tells how much solute is dissolved in a given amount of solution.

• Weight/ Volumes percent concentration, (w/v)% is the number of grams of solute dissolved in a 100mL of solution.

Question 25

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CONCENTRATION UNITS
WEIGHT/ VOLUME PERCENT

What is the equation given to determine the weight/ volume percent concentration?

💥💥See pg 23 for example💥💥💥

Answer 25

• Weight/ Volumes percent concentration, (w/v)% is the number of grams of solute dissolved in a 100mL of solution.

Weight/ volume
Percent concentration

(w/v)%= mass of solute (g)/ volume of solution (mL) • 100%

Question 26

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What is molarity?

Answer 26

Molarity is the number of moles of solute per liter of solution, abbreviated as M.

Molarity = M = moles of solute (mol)/ liter of solution L

• molarity is a conversion factor that relates the number of moles of solute to the volume of solution and occupies

Question 27

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What is dilution?

💥💡 pg 38

M1V1 = M2V2

Initial Final
Values Values

Answer 27

• dilution is the addition of a solvent to decrease the concentration of solute. The solution volume changes, but the amount of solute is constant.

M1V1 = M2V2

Initial Final
Values Values

Question 28

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COLLIGATIVE PROPERTIES

True or false?

1. colligative properties are properties of a solution that depend on the concentration of the solute, but not if identity.
2. The number of dissolved solute particles affect the properties of the solution, but that identity of the solute does not.
3. Colligative properties include the elevation of the boiling point, the lowering of the melting point, and the pressure due to osmosis.

Answer 28

True
True
True

Question 29

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COLLIGATIVE PROPERTIES
BOILING POINT ELEVATION

What is a volatile solute?

Answer 29

A volatile solute readily escapes into the vapor phase.
- evaporates easily and quickly
- think acetone

Question 30

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COLLIGATIVE PROPERTIES
BOILING POINT ELEVATION

What is a non-volatile solute?

Answer 30

• a non-volatile solute does not readily escape, so it has a negligible vapor pressure at a given temperature
- Evaporates slowly
- think oil

Question 31

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COLLIGATIVE PROPERTIES
BOILING POINT ELEVATION

True or False

The vapor pressure above a solution of a non-volatile solute is lower than the vapor pressure of the pure solvent.

Answer 31

True

Question 32

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COLLIGATIVE PROPERTIES
BOILING POINT ELEVATION

What is boiling point elevation?

Answer 32

• the boiling point elevation: a liquid solution that contains a non-volatile solute has a higher boiling point then the solvent alone

• the amount that the boiling point increases, depends on the number of dissolved particles

• one mole of any non-volatile solute raises the boiling point from 1 kg of H2O the same amount (about 0.51°C)

Question 33

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COLLIGATIVE PROPERTIES
FREEZING POINT DEPRESSION

What is freezing point depression ?

Pg 45 📽️📽️

Answer 33

• freezing point depression: a liquid solution that contains a nonvolatile solute has a lower freezing point than the solvent alone
• the amount of freezing point depression depends only on the number of dissolved particles
• one mole of any nonvolatile solute lowers the freezing point of 1 kg of H2O by the same amount (about 1.86°C)

Question 34

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OSMOSIS AND DIALYSIS

What is the semi permeable membrane?

Answer 34

• the membrane that surrounds living cells is a semipermeable membrane

• semipermeable membranes, allow water and small molecules to pass across, but ions and large molecules cannot

Question 35

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OSMOSIS AND DIALYSIS

What is osmosis?

Answer 35

• osmosis is the passage of a solvent, usually water, across a semipermeable membrane from a solution of low solute concentration to a solution of higher solute concentration

Question 36

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OSMOSIS AND DIALYSIS

What is osmotic pressure?

Answer 36

• osmotic pressure is the pressure that prevents the flow of additional solvent into a solution on one side of the semipermeable membrane.

Question 37

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OSMOSIS AND DIALYSIS

Two solutions with the same osmotic pressure are said to be….?

Answer 37

Isotonic

Solutions isotonic to the body:
• 0.92% (w/v) NaCl solution
• 5.0% (w/v) Glucose solutions

Question 38

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OSMOSIS AND DIALYSIS
FOCUS ON THE HUMAN BODY- OSMOSIS

What is a hypotonic solution?

Answer 38

A hypotonic solution has a lower osmotic pressure than body fluids

The concentration of particles outside the south is lower than the concentration of particles inside the cell

Water diffuses into the cell, so the south swells, and eventually the cell bursts

For red blood cells, the swelling and rupture is called hemolysis.

Question 39

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OSMOSIS AND DIALYSIS
FOCUS ON THE HUMAN BODY- OSMOSIS

What is a hypertonic solution?

Pg 50

Answer 39

A hypertonic solution has a higher osmotic pressure than body fluids

The concentration of particles outside the cell is higher than the concentration of particles inside the cell

Water diffuses out of cell, causing the cell to shrink

This process called crenation