Ch. 8/ Solutions Flashcards
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Solutions
MIXTURES
What is a pure substance?
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. 📍📍📍
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MIXTURES
What is a heterogeneous mixture?
• 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.
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MIXTURES
What is a homogenous mixture?
• 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
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MIXTURES
SOLUTIONS
What is a solution and what two parts does it consist of?
• 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
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MIXTURES
COLLOIDS AND SUSPENSIONS
What is a colloid?
• 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
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MIXTURES
COLLOIDS AND SUSPENSIONS
What is a suspension?
• 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,
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What is the Tyndall effect?
Pg 8
• Tyndall effect- light is scattered as it travels through a colloid making the light pathway visible
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ELECTROLYTES AND NONELECTROLYTES
What is an electrolyte?
An electrolyte is a substance that conducts in electric current in water
NaCl(aq) dissociates into Na+(aq) and Cl^- (aq)
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ELECTROLYTES AND NONELECTROLYTES
What is a non-electrolyte
A non-electrolyte is a substance that does not conduct an electric current in water
H2O2 does not dissociate
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ELECTROLYTES AND NONELECTROLYTES
What makes a strong electrolyte and what makes a weak electrolyte?
Pg 9 📽️
• a strong electrolyte dissociates completely and water to form ions
• a week electrolyte dissociates partially in water to form some ions, mostly uncharged molecules
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Review
ELECTROLYTES AND NONELECTROLYTES
List three solutes, species in solution, conductivity, and examples.
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
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SOLUBILITY GENERAL FEATURES
What is solubility?
• 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)
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SOLUBILITY GENERAL FEATURES
What is a saturated solution?
A saturated solution contains the maximum number of grams of solute that can dissolve
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SOLUBILITY GENERAL FEATURES
What is an unsaturated solution?
An unsaturated solution contains less than the maximum number of grams of solute that can dissolve.
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SOLUBILITY
BASIC PRINCIPLES
Solubility can be summed up as “like dissolves like.”
• 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.
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SOLUBILITY
BASIC PRINCIPLES
Solubility can be summed up as “like dissolves like.”
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
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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)
Exothermic
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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)
Endothermic
💥 See Pg 16 for rules of solubility of Ionic compounds
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When do SINGLE REPLACEMENT REACTIONS occur?
See pg 17 for activities series 📝
• single replacement reactions only occur when the element that is doing the replacing is more reactive than the element that is being replaced
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EFFECTS OF T AND P
TEMPERATURE (T) EFFECTS
True or False?
- For most ionic and molecular solids, solubility generally increases as temperature increases.
- by dissolving a solid in a solvent at a high temperature and allowing it to cool slowly, super saturated solution can be made.
- The solubility of a gas decreases with increasing temperature.
True
True
True
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EFFECTS OF T AND P
TEMPERATURE (T) EFFECTS
What is a supersaturated solution?
• A supersaturated solution contains more than the predicted maximum amount of a solute at a given temperature.
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SOLUBILITY– EFFECTS OF T AND P
~PRESSURE (P) EFFECTS
What is Henry’s law?
Pg 20 for image 📽️
• 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
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CONCENTRATION UNITS
WEIGHT/ VOLUME PERCENT
What does the concentration of a solution tell us?
• 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.
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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💥💥💥
• 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%
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What is molarity?
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
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What is dilution?
💥💡 pg 38
M1V1 = M2V2
Initial Final
Values Values
• 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
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COLLIGATIVE PROPERTIES
True or false?
- colligative properties are properties of a solution that depend on the concentration of the solute, but not if identity.
- The number of dissolved solute particles affect the properties of the solution, but that identity of the solute does not.
- Colligative properties include the elevation of the boiling point, the lowering of the melting point, and the pressure due to osmosis.
True
True
True
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COLLIGATIVE PROPERTIES
BOILING POINT ELEVATION
What is a volatile solute?
A volatile solute readily escapes into the vapor phase.
- evaporates easily and quickly
- think acetone
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COLLIGATIVE PROPERTIES
BOILING POINT ELEVATION
What is a non-volatile solute?
• a non-volatile solute does not readily escape, so it has a negligible vapor pressure at a given temperature
- Evaporates slowly
- think oil
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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.
True
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COLLIGATIVE PROPERTIES
BOILING POINT ELEVATION
What is boiling point elevation?
• 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)
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COLLIGATIVE PROPERTIES
FREEZING POINT DEPRESSION
What is freezing point depression ?
Pg 45 📽️📽️
• 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)
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OSMOSIS AND DIALYSIS
What is the semi permeable membrane?
• 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
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OSMOSIS AND DIALYSIS
What is osmosis?
• 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
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OSMOSIS AND DIALYSIS
What is osmotic pressure?
• osmotic pressure is the pressure that prevents the flow of additional solvent into a solution on one side of the semipermeable membrane.
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OSMOSIS AND DIALYSIS
Two solutions with the same osmotic pressure are said to be….?
Isotonic
Solutions isotonic to the body:
• 0.92% (w/v) NaCl solution
• 5.0% (w/v) Glucose solutions
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OSMOSIS AND DIALYSIS
FOCUS ON THE HUMAN BODY- OSMOSIS
What is a hypotonic solution?
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.
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OSMOSIS AND DIALYSIS
FOCUS ON THE HUMAN BODY- OSMOSIS
What is a hypertonic solution?
Pg 50
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
