TOPIC 8: SOLUTIONS AND SOLUBILITY HONORS CHEMISTRY Ms. Argenzio How can we describe solutions? How can we explain molecule-ion attraction in an aqueous solution? How can we use Table G to understand solubility curves? How can we use Table F to predict solubility and the products of double replacement reactions? What are the factors that affect solubility? What are the factors that affect the rate of dissolving? What are colligative properties and how do electrolytes affect them? How can we determine the concentration of solutions?
How can we describe solutions?How can we explain molecule-ion attraction in an aqueous solution?How can we use Table G to understand solubility curves? How can we use Table F to predict solubility and the products of double replacement reactions?What are the factors that affect solubility?What are the factors that affect the rate of dissolving?What are colligative properties and how do electrolytes affect them?How can we determine the concentration of solutions?
AIM: How can we describe solutions?
~~~~Homogenous Mixtures aka – SOLUTIONS~~~~
Solutions are homogeneous Dissolved particles will not come out of the
solution no matter how long its stands unless temperature changes or evaporation occurs
Liquid and gas solutions are clear and transparent (dissolved particles cannot be seen)
Cannot be filtered Single phased even though the components that
make it up can be of different phases
AIM: How can we describe solutions?
PARTS OF A SOLUTION
Solutions consist of solute and solvent (solution = solute + solvent )
Solute – dissolved substance (smaller portion of solution)
Solvent – substance in which the solute is dissolved (the larger portion of the solution)
AIM: How can we describe solutions?
TYPES OF SOLUTIONS Gas solutions – (air) gases have completely dissolved
in one another
Liquid Solutions – Consist of a solute which can be a solid, liquid, or gas dissolved in a solvent Ex: Carbonated water – CO2 gas in water Salt water – solid in water Antifreeze – ethylene glycol
Solid Solution – mostly solid dissolved in solid. It can also be a liquid or gas dissolved in a solid Ex: Alloys Brass – Cu/Zn
Bronze Cu/Sn
AIM: How can we describe solutions?
Homogeneous aka solutions/miscible (capable of being mixed)
A solution is produced when one substance dissolves in another
Salts are ionic
Heterogeneous mixture – nonuniform/immiscible
Heterogeneous mixtures are immiscible. They do not mix and do not dissolve
Saturated Solutions are in Equilibrium
AIM: How can we explain molecule-ion forces of attraction in an aqueous solution ?
Molecule ion attraction : Mixing ionic compounds with water form aqueous solutions of dissolved ions Polar water molecules attract to the ions tearing them apart from the other ions Crystal salt dropped in H2O
AIM: How can we explain molecule-ion forces of attraction in an aqueous solution ?
Saturated: has the maximum amount of solute dissolved in them. No more solute can be made to dissolve (100 seat restaurant with 100 people in it)
Unsaturated: has less than the maximum amount of solute dissolved in them. This means that more solute can be added to the solution and the additional solute would still dissolve( 100 seat restaurant with 40 people in it)
Supersaturated: Rare solution where the solution holds more solute than is theoretically possible, unstable where the excess will precipitate if the solution is agitated (100 seat restaurant with 120 people in it, then the manager comes in, he throws the extra 20 people out)
AIM: How can we describe solutions?
Using reference Table G!!!!! Up curves represent salts (direct relationship: increase T, increase solubility) Down curves represent gases (indirect relationship: increase T, decrease solubility )
AIM: How can we understand solubility curves?
Each line represents a saturated solution of a solute at different temperatures
Higher a line is at a given temperature the more soluble that substance is
Data tells us how many grams of solute can be dissolved in 100g of water a particular temperature
AIM: How can we understand solubility curves?
Any point on line represents a saturated solution.
Saturated solutions are at equilibrium Rate of dissolution is equal to the rate of crystallization
AIM: How can we use Table F to predict solubility?
AIM: How can we use Table F to predict solubility?
Table F gives us information on the solubility of various compounds in solutions
You can predict the solubility of a compound or the two products in a double replacement reaction
AIM: How can we use Table F to predict solubility?
DIRECTIONS:
1. Cross out the symbol of the first ion or element
2. Underline the symbol of the second ion or element
3. Use TABLE F to predict solubility
AIM: How can we use Table F to predict solubility?
EXAMPLE:
AIM: How can we understand and recognize double replacement reaction?
Double reactions contains 2 ionic compounds Every double replacement reaction will not
necessarily occur. There are 3 situations that ensure a DR occurs:
If one of the products is a solid One of the products is a gas A molecular substance such as water is formed
AIM: How can we predict the products and solubility of the products of DR reactions?
KI + Pb(NO3)2 _________ + ______________
1. Predict products – the reactants swap places2. Determine solubility of products
EXAMPLE: For the reaction between LiBr and BaNO3 predict the products and determine the solubility of the products
“If you are not part of the solution you are part of the precipitate”
Precipitate – insoluble solid (cant be dissolved)
Table F – SOLUBLE – dissolved INSOLUBLE – not dissolved
*right side of the table all insoluble and they all have exceptions
AIM: How can we use Table F and G?
DO NOW: Answer the Following Questions: 1. Identify the solute and solvent in air 2. If 106g of KNO3 are added to 100g H2O at 60C, what kind of solution is formed?
3. If 110g of KNO3 are added to 100g H2O at 50C, what kind of solution is formed?
4. If 60g of KNO3 are added to 100g of water at 50C, what kind of solution is formed? How can you make this solution saturated? 5. If 110g of KNO3 are dissolved in 100g of H2O at 62C, what kind of solution is formed? How can you make this solution saturated?
2/11/13 – D day
AIM: What are some factors that affect solubility?
Solubility: how much solute is dissolved in a given amount of solvent
Solubility is measured in grams of solute per 100 grams of solvent (mostly water)
Solubility must always be accompanied by a temperature
NaCl 36g/100g H2O @ 25C
AIM: What are some factors that affect solubility?
FACTORS THAT AFFECT SOLUBILTY:
Nature of the solute Temperature Pressure
Nature of the Solute All solute don’t dissolve to the same
extent in H2O
Examples:
PbCl2 1g/100g H2O @ 25C
ZnCl2 200g/100g H2O @ 25C
TEMPERATURE Solid Solutes – as T increases, Solubility
increases Liquid Solutes – as T increases, Solubility
increases Gas Solutes – as T increases, Solubility
decreases
PRESSURE Solid Solutes – as P increases, no effect Liquid Solutes – as P increases, no effect Gas Solutes – as P increases, Solubility
increasesApplying the principles of solubility and pressure, explain why soda goes flat when you open the can.
AIM: Factors affecting dissolving rate?
DO NOW: Answer the Following Questions: 1. Identify the solute and solvent in air 2. If 106g of KNO3 are added to 100g H2O at 60C, what kind of solution is formed?
3. If 110g of KNO3 are added to 100g H2O at 50C, what kind of solution is formed?
4. If 60g of KNO3 are added to 100g of water at 50C, what kind of solution is formed? How can you make this solution saturated? 5. If 110g of KNO3 are dissolved in 100g of H2O at 62C, what kind of solution is formed? How can you make this solution saturated?
3/25/14 – A day
AIM: What are some factors that affect the Rate of Dissolving?
Size of the particles – smaller particles dissolve faster than larger particles
Stirring – increase the stirring, increase the rate of dissolving
Temperature – increase the temperature, increase the rate of dissolving
Nature of the solute and solvent – “LIKE DISSOLVES LIKE RULE”
AIM: What are some factors that affect solubility?
LIKE DISSOLVES LIKE RULE
Like polarities will dissolve in like polaritiesPolars will attract polars (like), and repel
non-polars (opposites). Non-polars will attract non-polars (like), and repel polars (opposites)
Oil, which is non-polar, does not mix with water, which is polar (opposites repel)
AIM: What are some factors that affect solubility?
Critical thinking:
A student was working in a lab. Grease spilled all over his hands. He went to the sink to clean his hands. The grease, which was non polar, did not come off. Once the student used soap and water, all of the grease came off. EXPLAIN
AIM: What are colligative properties ?
Colligative property physical properties of solutions that depend on the concentration of solute in a given amount of solvent
When any pure solvent forms a solution two things occur: 1. Boiling point elevation2. Freezing point depression
NOTE: The addition of electrolytes and non electrolytes will raise the boiling point and lower the freezing point of a solution. However, the electrolyte will have a greater effect
• Summary – the measure of changes in boiling point and freezing point are dependent on:
-Solute (electrolyte vs. nonelectrolyte) -Number of particles in solution-Concentration
AIM: How do electrolytes and non electrolytes affect the boiling point and
freezing point of solutions?
AIM: What are electrolytes and how do they behave?
ELECTROLYTES Ionic substances
(salts) Acids (HX) Bases (MOH)
NON-ELECTROLYTE Sugars (C6H12O6) Alcohols R-OH
Summary • Electrolytes conduct and turn a light bulb tester on. When
placed in aqueous solutions electrolytes dissociate, ionize or break apart
• None electrolytes do not conduct and will not turn on a light bulb tester. When placed in water non-electrolytes do not dissociate, ionize or break apart
Exercise: Determine if the following are electrolytes or non-electrolytes and sub classify
E or NE Acid Base Ionic/Salt
HCl
C6H12O6
NaOH
CH3OH
ZnCl2
EXCEPTIONS
ACID CH3COOH = HX
Although acetic acid or vinegar does not look like HX, it is still an acid – exception!
BASE NH4OH = MOH
Although ammonium hydroxide does not look like MOH, it is still a base – exception!
AIM: How can we determine the concentration of solutions?Concentration: the amount of the solute dissolved in the solution.
For solutions there are several ways to express concentration : 1. Grams of solute/100mL of solvent (TABLE
G)2. Molarity 3. Parts per million 4. % by mass5. % by volume
AIM: How can we determine the molarity of solutions?
Molarity (M) – the number of moles of solute (n) divided by the volume (V) of the solution in liters
**important to note that molarity is not moles of solute per liter of solvent !!
Percent by Mass
Labels often list the concentration of the ingredients as a percent by mass. Fertilizers list the active ingredients as a percentage of the entire mass of fertilizer
Percent by mass – the mass of the part divided by the mass of the whole solution
EX: What is the percent by mass of sodium hydroxide if 5.00g of NaOH are added to 50.00g of H2O?
Percent by Volume Percent by volume – used when
two liquids are mixed to form a solution
A label on a bottle of alcohol shows a common example
% by volume is the ratio of the volume of an ingredient divided by the total volume and expressed as a percent
EX: What is the percent by volume of alcohol if 50mL of ethanol is diluted with water to form a total volume of 3000mL
How can we understand what parts per million means? If you divide a pie equally into 10
pieces, each piece would be a part-per-ten; i.e., one-tenth of the total pie
If you cut this pie into a million pieces, each piece would be very small and would represent a millionth , or part per million, of the original pie
How can we determine concentration of a solution in parts per million?
Parts per million is the ratio between the mass of the solute and the total mass of solution
This method is useful for extremely dilute solutions when molarity and percent mass would be too difficult to interpret
Questions:
Carbon dioxide has a solubility of 0.0972g/100g H2O @40dC. Expressed in parts per million this concentration is closest to what value?
A substance has a solubility of 350ppm. How many grams of the substance are present in 1.0L of a saturated solution?
