SOLUTIONS

Essential Questions: What are solutions? What are the components of a solution? Solutions: 1. Homogeneous mixtures 2. Stable: NaCl in H 2 O (does not settle out). 3. Composed of a solvent and a solute, which can pass through filter paper.

Solvent: 1. Dissolving medium (substance). 2. Dissolves a solute. 3. Part of a solution found in the largest amount Ex: A solution of NaNO 3 NaNO 3 -solute H 2 O-solvent H 2 O-solvent

Solute: 1. S ubstance that is dissolved. 2. B ecomes dispersed in a solvent. 3. P art of a solution that is found in the smallest amount. * Solutes and solvents may be gases, liquids or solids.

Essential Questions: What is solubility? How can you determine is a substance is soluble in another substance? Solubility: 1. How much a solute will dissolve in a solvent. 2. Expressed in grams of solute per 100 grams of solvent

Substances that dissolve most readily in water are: 1. Ionic compounds (dissociate into ions.). Ex. NaCl 2. Polar covalent molecules

Aqueous solution- A water solution that contains a dissolved substance. Solution Process: 1. H 2 O particles are in constant motion. 2. When NaCl is added, the H 2 O molecules collide with it. 3. The negative end of water attracts the Na + ions. 4. The positive end of water attracts the Cl - ions.

Is this what is really happening?

5. The dipole attraction is so strong it breaks the ionic bonds. Ex. However in some ionic compounds, if the attraction for ions (ionic bond) is stronger than the dipole attraction of H 2 O, the ionic compound does not dissolve. Exs. BaSO 4 and CaCO 3

Polar solvents dissolve polar compounds. Ex. NaCl in H 2 0 Polar solvents dissolve polar compounds. Ex. NaCl in H 2 0 Nonpolar solvents dissolve nonpolar compounds. Ex. Oil and Gasoline Nonpolar solvents dissolve nonpolar compounds. Ex. Oil and Gasoline Like dissolve like Like dissolve like

Miscible- Two liquids that can dissolve in each other proportions. Ex: water and ethanol Immiscible- liquids that are insoluble in each other. Ex: oil and water

Essential Questions: What are electrolytes and nonelectolytes? How can you determine what substances are electrolytes of nonelectolytes? Electrolytes: 1. Compound that conducts electricity when it is in an aqueous solution or in the molten state. 2. Requires ions that are mobile. All ionic compounds are electrolytes because they dissociate into ions. Ex: CuSO4 and NaCl Barium Sulfate is an ionic compound that conducts electricity in the molten state but not in an aqueous state solution. Why? Does not dissociate into ions. Ionic bonds are stronger that the dipole attractions

Nonelectrolytes: 1. Does not conduct electricity in aqueous solutions or in the molten state. 2. Many molecular compounds are nonelectrolytes. Ex. Sucrose 3. Some polar molecular compounds are nonelectrolytes in the molten state, but are electrolytes in an aqueous solution. Exs: NH 3 (g) + H 2 0 (L)  NH +4 (aq) + OH - (aq) HCl(g) + H 2 O (l)  H 3 O + (aq) + Cl - Forms ions

Essential Question: What are the factors affecting the rate of dissolving? Factoring Influencing the Rate of Dissolving: Stirring(agitation): 1. Increases the dissolving rate because more solvent is brought in contact with solute. 2. Isn't influenced by how much solute is dissolved.

Temperature: Increasing kinetic energy (an increase in temperature) will lead to an increase in the number and force of collisions between solute and solvent

Particle Size: 1. Decreasing particle size will increase the rate of dissolving Ex sugar cube versus granulated sugar 2. Smaller particles have greater surface area.

Essential Questions: What are unsaturated, saturated, and supersaturated solutions? How do you use Table G to determine the saturation of a certain compound ion a solution? Using Table G: Unsaturated: 1. A solution that contains less solute than it can hold at a given temperature and pressure 2. Adding additional solute will dissolve until the solution is saturated.

Saturated: 1. A solution that contains the maximum amount of solute for a given quantity of solvent at a constant temperature and pressure. Ex: 36.3 g NaCl will dissolve in 100 g of water at 25 C. Adding additional NaCl will not dissolve in the water. * Rate of dissolving = Rate of crystal formation.Supersaturated: 1. Solution that contains more solute that it can theoretically hold at a given temperature and pressure. 2. Solution is very unstable. Ex: Rock candy

Essential Questions: What two factors that affect the solubility of a substance? How do these factors affect the rate? Factors Affecting Solubility: A. Temperature B. Pressure

Temperature: 1 Increasing temperature generally increases solubility of a solute. Ex. sugar in water 2. Increasing temperature decreases the solubility of a gas solute in a liquid solvent. Ex: thermal pollution Pressure: 1. Changes in pressure will have little impact on the solubility of solids and liquids. 2. Strongly influences the solubility of gases (solute) in liquid (solvent) 3. Increased pressure on the gas above a liquid will increase the solubility of the gas in a liquid. Ex. Carbonated beverages (CO 2 dissolved in H 2 0)

Essential Questions: What is concentrated and a dilute solution? What is Molarity? Concentration-measure of the amount of solute that is dissolved in a given quantity of solvent. Dilute Solution- solution that contains a small amount of solute Concentrated - solution-solution that contains a large amount of solute. Ex: 1 g NaCl/100g H2O—dilute 30 g NaCl/lOOg H2O—concentrated

Molarity(M): 1. Also known as molar concentration 2. # of moles of solute dissolved in 1 liter of solution. M = moles of solute 1 liter of solution 1 liter of solution * Table T Ex: 3M NaCl - 3 molar solution of sodium chloride or a solution with a Molarity of 3.

Molarity Problems: A. What is Molarity of a solution that contains 4.0 mol of NaOH in.50L of solution? M = moles of solute liters of solution liters of solution Known Unknown Amount of NaOH = 4.0 mol Molarity= Volume of a solution=.50L M= 4.0 mol of NaOH.50 L.50 L M = 8.0 M = 8.0

B. How many moles of solute are needed to prepare 2.5 L of.60 M solution? Known Unknown Volume of solution = 2.5 L Moles of solute= Molarity =.60 M = moles of solute liter of solution liter of solution M x liters of solution = moles of solute 60 M x 2.5L = moles of solute =1.5 moles of solute =1.5 moles of solute

C. A person wishes to prepare a 2.00M solution using 2.5 moles of solute. Calculate the final volume of the solution. M = moles of solute liters of solution liters of solution Known Unknown Molarity = 2.00 Volume= Moles of solute = 2.5 M = moles of solute liters of solution liters of solution liters of solution = moles of solute M Liters of solution = 2.5 moles 2.00M 2.00M = 1.25L

D. What is the Molarity of a solution containing 82.Og of Ca (NO3)2 in 2.0 L of solution? Known Unknown Mass of Ca (NO3)2 = 82.0g Molarity= Volume of solution=2.0L Determine GFM of Ca(NO3)2 Ca=1atom x 40 amu N =2 atoms x 14 amu =28 amu O = 6 atoms x 16 amu = 96 amu =164 amu Convert grams to moles: 82.0g Ca (NO3)2 x 1 mole Ca (Na0)2 164gCa(NaO3)2 =.50 mol Ca(NO3)2 M = moles of solute liters of solution =.50 moles Ca (NaO3) of solution M=.25

E. How many grams of urea (CH 4 N 2 0), with a molar mass = 60.1 grams are needed to make 200 ml of 1.50 M solution? Known Unknown Molar mass of urea= 60.1 g grams of urea Volume of solution =200 ml M= ml x 1 L x 1.5 moles urea x 60.1g urea 1000ml 1 L 1 mole urea = 18 g urea

Essential Questions: What is percent solution? What are the types of percent solutions? Percent Solution- Way to describe the concentration of solution by the % of a solute in solvent. Types of Percent Solution: A. Percent by Mass B. Percent by Volume C. Parts per Million (ppm)

A.Percent by mass: Percent Mass(decomposition)= Mass of part (solute) x 100% Mass of whole (solution) * Table T

Ex: A student dissolves 25.0 g of glucose in 475 g of H 2 0. What is the concentration of the glucose solution? Percent mass= 25.00g glucose x 100% 475 g H g glucose 475 g H g glucose = 5% glucose What is the percent by mass of sodium hydroxide if 2.50 g NaOH are added to a 50.Og of water? Percent mass= mass solute Mass solution x 100% Mass solution x 100% 2.5 g NaOH 50.0g H g NaOH x 100% = 4.76% NaOH

B. Percent by volume: Percent by volume=Volume solute Volume of solution x 100% Volume of solution x 100% Ex: A solution is prepared by dissolving 90 ml of H 2 O 2 in enough water to make 3000ml of solution. What is the concentration of the hydrogen peroxide solution? Percent by volume = volume solute Volume solution x 100% Volume solution x 100% =90 ml H 2 O ml of solution x 100% 3000 ml of solution x 100% = 3% = 3%

What is the percent by volume of alcohol if 50 ml of ethanol is diluted with water to form a total volume of 300 ml? What is the percent by volume of alcohol if 50 ml of ethanol is diluted with water to form a total volume of 300 ml? % by volume = volume solute volume solution x 100% volume solution x 100% = 50.0 ml ethanol 300 ml solution x 100% 300 ml solution x 100% = 16.7%

C. Parts Per Million - used with very dilute solutions Exs: Chlorine in a swimming pool, amount of arsenic allowed in drinking water-.05ppm for 5 g in 100,000,000 g of H 2 0 Exs: Chlorine in a swimming pool, amount of arsenic allowed in drinking water-.05ppm for 5 g in 100,000,000 g of H A certain gas has a concentration of 2 mg per 100 g of water. What is the concentration of the gas in parts per million? Parts per million solute (ppm) = mass solute x 10 6 mass of solution mass of solution1g=1000mg 2 mg=.002g.002mg solute.002mg solute 100gH 2 0 x lO 6 100gH 2 0 x lO 6 = 2 x x 10 6 = x 10 6 = x 10 6

2. Approximately g of oxygen can be dissolved in ml of water at 20 C. Express this in terms of parts per million. ppm=mass solute mass solution x 10 6 mass solution x 10 6 =.0043g oxygen solution x lO 6 =.3 x lO -5 x l0 6 =43ppm =43ppm

Preparation of a solution of Known Concentration: Ex: What mass of Na 2 CO 3 is required to prepare 2.00L of a 0.25 M Na 2 CO 3 solution? Known Unknown Concentration of solution=.25 M mass of Na 2 CO 3 Volume solution = 2.00L Find the number of moles of Na2CO3 M = moles solute Liters of solution M x liters of solution = moles solute 2.00L x.25 molesNa2CO3 1 liter =500 moles Convert moles to grams. Use GFM Na= 2 atoms x23amu=46 amu C= 1 atom x 12 amu= 12 amu 0= 3 atom x 16 amu= 48 amu = amu.500 mole x 106gNa 2 CO 3 1 mole = 53.0gNa 2 CO 3

Dilution- reduces the number of moles of solute per unit volume, but the total number of moles of solute in solution does not change. Moles of solute = M 1 V 1 = M 2 V2 1. How should a 12M stock solution be diluted in order to prepare.80 L of 3.0 M working solution? M stock x V stock =M working x V working 12 M x V = 3.0M x.80L V=3.0Mx.80L 12 M 12 M V=.20L V=.20L

2. If 300 ml of a 6.00M stock solution is diluted to produce a 2.0 M working solution, what is the volume of the working solution? M stock x V stock =M working x V working 6.0 M x 300ml=2.0 M x V 6.0 M x 300ml=V 2.0M =900ml

Essential Questions: What are Colligative solutions? How is the BP and FP affected by it? Colligative Properties of Solutions: Colligative Properties: 1.Properties that depends upon the number of solute particles. 2.Directly proportional to the number of solute particles dissolved in a solvent. 3. Increases the BP for every mole of solute dissolved in a solvent. Ex: NaCl  Na+ + CL- (2moles of particles) CaCl2  Ca+2 + Cl- + Cl-  Thus CaCl 2 will increase the BP and decrease the FP more than NaCl