SOLUTIONS

Chemistry Standards: Notecards 6A. Students know the definitions of solute and solvent. 6B. Students know how to describe the dissolving process at the molecular level by using the concept of random molecular motion. 6C. Students know temperature, pressure, and surface area affect the dissolving process. 6D. Students know how to calculate the concentration of a solute in terms of grams per liter, molarity, parts per million, and percent composition.

Group Activity: Part I: Matching Vocab terms with definition Part II: Create a concept map using vocab terms --cut out the remaining terms --arrange vocab using the italicized topics --include linking phrases

Dissolving Ionic Substance See video http://programs.northlandcollege.edu/biology/Biology1111/animations/dissolve.html

*Molecules in a solution are in a constant motion 6B. Students know how to describe the dissolving process at the molecular level by using the concept of random molecular motion. *Molecules in a solution are in a constant motion *If intermolecular force is strong between the solvent and solute, then it will dissolve *Intermolecular forces dependent on the structure of molecules Ex. Polar water (solvent) can dissolve sugar and ethanol (solutes with polar parts)

6C. Students know temperature, pressure, and surface area affect the dissolving process. Increase Surface Area =_____Solubility Explain why? Increase Temperature = _______ Solubility Explain why? Increase mixing = ______solubility Explain why?

“Like-dissolves-like” Polar solvent will dissolve _____ solute Non-polar solvent will dissolve ______ solute

Solubility Curve *Each solution has a unique solubility curve. *Describe the relationship of solute and temperature? Solubility Curve *Solute amount and temperature are directly related. --Increase in solute means the need for increase in temp. to reach saturation

Solubility Curve

Molarity *Often used to describe the concentration of a solution in a given volume. Symbol is “M”. Molarity = moles of solute = mol liters of solution L *If given in grams, change to moles by dividing with molar mass. Convert all volume to Liters. Remember: 1L = 1000mL Ex. #1. Calculate molarity of 1.56g of HCl added to water. The total volume of the solution is 26.8mL ANSWER: 1.59 M of HCl

Practice Problem #1. You created a salt solution where you have 10 moles of salt added to 300mL of water. What is the molarity of this solution? #2. You added 10g of NaCl (molar mass 58.5g/mol) to beaker “A” and dissolved it in 150mL water. What is the molarity of this solution? If you take 0.1L of this salt solution, transfer to beaker “B”and then add more water so the new volume is 0.3L, what is the molarity in beaker “B” 1.) 33.3M 2a.) 1.14M 2b.) 0.38M

Practice Problem Ex. #2. Calculate the mass (in grams) of NaOH (molar mass is 40g/mol) of a solution with a molarity of 0.200M with a volume of 1.00L? ANSWER: 8 grams #3.When solid FeCl3 dissolves, it produces ions as follows: FeCl3  Fe3+ + Cl- Balance the equation and determine the molarity of the two ions (the products) if you have 1M of FeCl3 ANSWER: 1M Fe3+ and 3M Cl-

Mass Percent Mass percent = mass of solute x 100 mass of solution Mass of solution = grams of solute + grams of solvent Example: You mix 10g of ethanol with 65g of water. What is the mass percent of ethanol in this solution? Answer: Mass % = 10g ethanol x100 10g ethanol+65g water 10g x100 = 13.33% mass percent of ethanol 75g

Practice Problems: NOTE: 1mL of water = 1g 1.) A bottling company adds 20g of CO2 in each 300mL tonic water. What is the mass percent of CO2? 2.) You decided to create a KoolAid drink. A packet has about 150g of KoolAid powder and you add it to 1L of water. What is the mass percent of KoolAid in the water? 3.) You add 30g of solute to a water solution. How much water should you have to get a 40% mass percent of solute to water? 1.) 6.25% 2.) 13% 3.) 45 g of water added (total solution is 75 g)

Parts per million (ppm) is a ratio of parts of solute to one million parts of solution, and is usually applied to very dilute solutions. Note: 1 mL of water = 1 gram OR 1L = 1000g Steps: divide the mass of the solute by the total mass of the solution (same as mass %) Answer from #1 multiplied by X 106 and expressed as parts per million (ppm) Ex. What is the concentration, in parts per million, of a solution in which 480 grams of sodium chloride, NaCl, is dissolved in 4 liters of solution (water) 480 g = 0.12  0.12 x (1x106) = 1.2x105 ppm 4000 g

Grams per liter (g/L) Mass of solute added to a solution Ex. A solution of sodium hydroxide, NaOH, contains 12 grams of solute in 4000 mL of solution. What is the concentration of the solution in grams/Liter? 12grams = 3 g/L 4 liters

Practice Problems: 1. What is the concentration of a solution in grams/Liter when 0.25 moles of sodium chloride, NaCl, is dissolved in 2000mL of solution? 2. What is concentration, in parts per million, of a solution in which 50 grams of aluminum oxide, Al2O3, is dissolved in a solution using water (total volume= 500 mL)? The solvent is water. 3. A solution of sugar contains 35 grams of sucrose, C12H22O11 in 65 mL of water. What is the concentration in parts per million of the solution?

Dilution– changing concentration by changing the total volume or moles of solute (M1) (V1) = (M2) (V2) Final Volume Initial Molarity Final Molarity Initial Volume (amount transferred)

ACTIVITY: Molarity of Food Coloring Solution Assume the original food color solution (#1) has a molarity of 50 M (moles/liter). The solvent is water. (remember that 1L = 1000mL) If we take 10mL from solution #1 and transfer to a new container (#2), how many moles of the food color did we transfer? After transferring 10mL of solution #1 to container #2, we diluted the solution and added 90mL of water. What is the new concentration? #2 Moles? / Molarity? #1 50M 10 mL of #1

Dilution Practice Problem (M1) (V1) = (M2) (V2) SOLUTION A SOLUTION B 30 mL of the original solution (50M) was diluted using water to a new total volume of 100 mL. What is the new molarity of this diluted solution? An unknown volume from the original solution (50M) was transferred to a new container. Water was added to this sample to a new volume of 0.1L thus creating a new concentration of 2.5 mol/L . What was the original volume transferred?

Dilution

Solubility Lab 1 2 3 4 Dye A 5 6 7 8 Dye B 9 10 11 12 Dye C

Mole Fraction Read the additional worksheet and answer the following practice problems.

Review for Quiz Know all key vocabs for solutions AND thermodynamics What does each sign for thermo mean Read solubility graphs Factors affecting solubility Solubility Lab including research question Calculate (formulas will be provided) -- molarity --parts per million -- mass percent -- g/L -- dilution --H, S, G

Review Problems: 20g. Of NaOH is dissolved in water to make a solution with a total volume of 500 mL. The molar mass of NaOH is 40g/mol while the molar mass of water is 18g/mol. (remember 1mL of water = 1g) A. What is the molarity of the solution? B. What is the mass percent of NaOH ? C. Calculate the grams/liter D. Calculate the parts per million

Review Problems 2. Calculate the new molarity that results when 250 mL of water is added to a solution with the original molarity of 0.33M of HCl and volume of 185mL. Add 250mL of water ?=M2 0.33 mol/L 185mL

Review Problems: 3. You have a 10% NaCl solution with a total mass of 50 grams. The original solution was then diluted by adding 300g of water. A. What is the mass of NaCl in the solution? B. What is the new percent mass of NaCl? B. Calculate the ppm of the diluted solution

Additional Questions 116g of KF is dissolved in enough water to make 4L of solution. Calculate the ppm. 280g of CaO is dissolved in enough water to make 1500mL of solution. CaO has a molar mass of 56g/mol. What is the molarity? 60g of HNO3 is dissolved in enough water to make 10 L of solution. What is the mass percent of HNO3

Extra Credit for Solution Quiz *Show your solution and include units --You have a solution with a molarity of 0.33 mol/L and initial volume of 75mL. You diluted it by adding 125 mL of solvent (water). What is the new molarity of the solution?

Per 1-3: Chp. 16 Vocabulary Words Read the chapter Create a table below. Use the key terms listed on page 531, only sections 16.1-16.4 Term Definition (paraphased) Mnemonic (Formula, symbol, drawing, analogy) Acid Base

Per 4-6: Chp. 15 Vocabulary Words Read the chapter Create a table below. Use the key terms listed on page 476. Term Definition (paraphased) Mnemonic (Formula, symbol, drawing, analogy) Acid Base