Chemistry Regents
Mr. Markic
Page 1 of 10
Chapter 15 - Water and Aqueous Systems
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This creates:
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Surface Tension
• The ___________force, or pull, that tends to minimize the surface area of the liquid
Surfactant
• Any substance that ______________ with the ___________bonding _________water molecules
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__________________ surface tension
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Examples:
Vapor Pressure
• Is the result of molecules ___________from the surface of the liquid and entering the vapor phase
Water in the Solid State
• Ice is ________ dense than water
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Structure of ice is a regular open framework
Homogeneous Aqueous Systems
• Aqueous Solution – water that contains _________________substances
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Solvent – the ________________medium (__________)
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Salt is the ___________ (gets ___________or ___________in the water)
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NaCl (__) + H2O (__) → NaCl (___)
Chemistry Regents
Mr. Markic
Page 2 of 10
Electrolytes
• A compound that __________________ electric current when in _______________solution or in the
_____________state
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All ionic compounds are __________________ because they
__________________ into ions
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Strong electrolytes – compounds dissociate ________________as separate
ions
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Weak electrolytes – conducts electricity poorly because ions/molecules
__________________________ completely
Nonelectrolyte
• A compound that does _______ conduct an electric current in wither aqueous solution or molten state
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Examples:
Sample Exercise
Which of the following substances dissolve appreciably in water?
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HCl
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CH4
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MgSO4
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NH3
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NaI
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CaCO3
Decide which compounds are more likely to dissolve in water and which are more likely to dissolve in gasoline
a. CCl4
c. Methane (CH4)
b. Na2SO4
d. KCl
Sample Exercise
Calculate the percent by mass of water in washing soda, sodium carbonate decahydrate (Na2CO3  10H2O)
Practice Problems
What is the percent by mass of water in CuSO45H2O?
Chemistry Regents
Mr. Markic
Page 3 of 10
Calculate the percent by mass of water in calcium chloride hexahydrate (CaCl26H2O)?
Write equations to show how these substances ionize or dissociate in water
a. NH4Cl
c. HC2H3O2
b. Cu(NO3)2
d. BaCl2
Chapter 16 - Solutions
Solution Formation
• How quickly the solute dissolves in a solvent
• Rate can be increased by increasing:
1.
2.
3.
1.
____________________
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2.
__________________ the solute increases the chance for the solvent to react and form a solution
____________________
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At high temperatures, the ______________ energy of molecules is greater than at lower temperatures
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The more rapid motion of molecules leads to an increase in ________________ and ___________ in
________________ between molecules
3.
____________________________
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Increasing the surface area of a solute increases the chances for a reaction
____________________
• Is the amount of substance that dissolves in a given quantity of a solvent at a given temperature to
produce a __________________ solution
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________________ + _________________  ____________________
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Ex: NaCl(s)(solute) + water(l)(solvent)  NaCl(aq) (solution)
Chemistry Regents
Mr. Markic
Page 4 of 10
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Saturated solution – contains the ___________________ amount of solvent at constant temperature
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Unsaturated – a solution that contains ___________ solute than a saturated solution
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Miscible – two liquids that ____________________ in each other
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Immiscible – liquids that are __________________ in one another
Factors Affecting Solubility
1. ________________________
• Affects the solubility of ___________, _______________, and ______________ solutes in a solvent
2. ______________________
• Affects only the solubility of ________________ solutes
1.
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Temperature
Table _________________________
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The solubility of most solid substances __________________ as temperature _________________
(__________________)
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Gases are ___________ soluble in liquids when temperatures are _____________ (_______________)
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Supersaturated solution – contains more _______________ that it can theoretically hold at a given
temperature
Sample Exercise
At what temperature will the solubility of KNO3 be 50 g/per 100g of H2O? At 100 g of KNO3?
How much KClO3 is needed to saturate 50 g of H2O at 90C?
How many grams of NaNO3 will precipitate if a saturated solution of NaNO3 in 200g H2O at 50°C is cooled to
20°C?
The solubility of KCl in water is 34.0 g KCl/100g H2O at 20°C. A warm solution containing 50.0 g KCl in 100 g
H2O is cooled from 75°C to 20°C.
a. How many grams of KCl remain dissolved?
b. How many grams came out of solution?
Chemistry Regents
Mr. Markic
Page 5 of 10
A solution contains 70 grams/100 g H2O at 60°C. Determine if the solution is unsaturated, saturated, or
unsaturated for: KI, NaNO3, HCl, KNO3
Which solution has the highest solubility in 100 g of H2O at 40°C?
A solution contains 14 g of KCl in 100 g of water at 40°C. What is the minimum amount of KCl that must be
added to make this a saturated solution?
How many grams of the compound KCl must be dissolved in 200 g of water to make a saturated solution at
60°C
Which amount of the compound dissolved in 100 g of water at the stated temperature represents a solution
that is saturated?
(1)
(2)
(3)
(4)
20 g KClO3 at 80°C
40 g KNO3 at 25°C
40 g KCl at 60°C
60 g NaNO3 at 40°C
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Pressure
Increasing pressure prevents ______________________
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Increasing pressure makes gaseous molecules _____________ soluble in liquid form
2.
Concentrations of Solutions
• Molarity (M) - The number of moles of a solute dissolved in 1L of solution
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Also known as _____________________________
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Molarity (M) = liters of solution
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Table T
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Dilute Solution – one that contains a _______________ amount of solute
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Concentrated Solution – contains a ________________ amount of solute
moles of solute
Chemistry Regents
Mr. Markic
Page 6 of 10
Sample Problem
Household laundry bleach is a dilute aqueous solution of sodium hypochlorite (NaClO). How many moles of
solute are present in 1.5 L of 0.70 M NaClO?
Practice Problems
How many moles of ammonium nitrate are in 335 mL of 0425 M NH4NO3?
How many moles of solute are in 250 mL of 2.0 M CaCl2? How many grams of CaCl2 is this?
A saline solution contains 0.90g of NaCl per 100.0 mL of solution. What is its molarity?
How many grams of solute are present in 1.5 L of 0.20M Na2SO4?
Making Dilutions
• Making a solution ____________ concentrated by ________________ it with more solvent
• M1 x V1 = M2 x V2
• Volumes can be in liters or in milliliters as long as the same units are used for both V 1 and V2
Sample Problem
How many milliliters of aqueous 2.00 M MgSO4 solution must be diluted with water to prepare 100.0 mL of
aqueous 0.400 M MgSO4?
Chemistry Regents
Mr. Markic
Page 7 of 10
Sample Exercise
How many milliliters of a solution of 4.00 M KI are needed to prepare 250.0 mL of 0.760 M KI?
How could you prepare 250 mL of 0.20 M NaCl using only a solution of 1.0 M NaCl and water?
Parts per Million (Table T)
• Ratio between mass of solute and total mass of solution
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Useful for very ___________ solutions
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Table T
𝒈𝒓𝒂𝒎𝒔 𝒐𝒇 𝒔𝒐𝒍𝒖𝒕𝒆
parts per million = 𝒈𝒓𝒂𝒎𝒔 𝒑𝒆𝒓 𝒔𝒐𝒍𝒖𝒕𝒊𝒐𝒏 x 1 000 000
Carbon dioxide gas has a solubility of 0.972 g/ 100 g of H2O at 40°C, express this in parts per million.
Approximately 0.0043g of oxygen can be dissolved in 100.0g of water at 20 oC. Express this in terms of parts
per million.
Colligative property • A property that depends on the __________________ of solute particles, _______ their identity
• Three important examples in solutions:
o __________________________________
o __________________________________
o __________________________________
Chemistry Regents
Mr. Markic
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Page 8 of 10
Vapor-Pressure Lowering
a measure of the force exerted by a gas ______________ a liquid
Solutions with nonvolatile (not easily ___________________) solutes have _____________ vapor
pressures than pure solvents
o E.x. Salt water has a lower vapor
pressure than pure water
Water forms a “__________” around dissolved
particles
This leaves fewer water molecules with enough KE to escape as vapor
The decrease in a solution’s vapor pressure is proportional to the ______________ of particles the
solute makes in a solution
 E.x. NaCl is 2x as effective as glucose, CaCl2 is 3x as effective as glucose
Freezing-Point Depression
 ____________________ in temperature between the freezing point of a solution and the freezing
point of the pure solvent
 Solutions have _______________ freezing-points than pure solvents
 The presence of a solute disrupts the formation of the orderly pattern found in a solid
 Therefore, _________________ KE must be removed before the solution can freeze
 The magnitude of the freezing-point depression is _________________ to the number of solute
particles dissolved in the solvent
o Why would CaCl2 be better than NaCl for melting ice?
3.
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Boiling-Point Elevation
The difference in temperature between the boiling point of a solution and the boiling point of the pure
solvent
Boiling Point – is the temperature at which the vapor pressure of the liquid phase _______________
the atmospheric pressure
Solutions have _______________ boiling-points than pure solvents
Recall… _______________________________________________________
Therefore, it takes _______________ KE for the solvent
particles to overcome the attractive forces that keep
them in the liquid
The magnitude of the boiling-point elevation is
_______________________ to the number of solute
particles dissolved in the solvent
Chemistry Regents
Mr. Markic
Page 9 of 10
Sample Exercise
• An equal number of moles of KI and MgF2 are dissolved in equal volumes of water. Which solutions
has the higher:
1. Boiling point
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2. Vapor pressure
3. Freezing point
Why is salt (NaCl) put on icy roads and sidewalks in the winter?
Assume equal aqueous concentrations of each of the following substances. Which has the lowest freezing
point?
(1) C2H22O6
(3) C12H22O11
(2) CH3OH
(4) NaOH
Which solution has the highest boiling point?
(1) 1.0 M KNO3
(3) 1.0 M Ca(NO3)2
(2) 2.0 M KNO3
(4) 2.0 M Ca(NO3)2
Which solution has the highest boiling point?
a) seawater
b) 1.0M KNO3 or
c) 0.100M KCl or
How does the freezing point of a 1.5M solution of potassium nitrate compare to a 1.5M solution of sodium
nitrate?
Vapor Pressure & Boiling
 Liquids are held together by _____________________________
 Some particles at the surface of the liquid have sufficient energy to escape & enter the gaseous phase
o __________________________
 Vapor pressure = the _________________ that these gaseous particles exert _____ the liquid below
 What will happen to the vapor pressure as the temperature is increased?
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As temperature _________, vapor pressure __________
At some point the vapor pressure ________ atmospheric pressure
Gases vaporize not only at the surface, but also within the liquid (_______________)
This is the boiling point -
Chemistry Regents
Mr. Markic
Page 10 of 10
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What is the vapor pressure of water at 105°C?
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What is the vapor pressure for a sample of ethanoic acid at 100°C?
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Which of the substances on Table H has the greatest intermolecular forces of attraction between
molecules?
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Which of the substances on Table H has the weakest intermolecular forces of attraction?
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What is the normal boiling point for water?
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What is the vapor pressure of water at its normal boiling point?
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At what temperature will water boil at a pressure of 30 kPa?
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At what temperature will water boil at a pressure of 145 kPa?
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As the pressure on a liquid is changed from 100 kPa to 120 kPa, the temperature at which the liquid will
boil will be?