Solution Concentration Notes CP Chemistry Chapter 14.
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Transcript of Solution Concentration Notes CP Chemistry Chapter 14.
Solution Concentration
NotesCP ChemistryChapter 14
Concentration• definition: the measure of how much solute is
dissolved in a specific amount of solvent• can be dilute to concentrated• can use specific numerical quantities to measure
concentrationo % by masso % by volumeo dilutionso molarity
Percent by Mass & Percent by Volume
100solution
soluteionconcentratpercent
100)(
solventsolute
soluteionconcentratpercent
Percent by Volume Practice I
1. What is the percent by volume of ethanol in a solution that contains 35 mL of ethanol dissolved in 115 mL of water?
100)(
solventsolute
soluteionconcentratpercent
Percent by Volume Practice I cont’d
2. If you have 100 mL of a 30% aqueous solution of ethanol, what volume of ethanol and water are in the solution?
Percent by Volume Practice I cont’d
3. What is the percent by volume of isopropyl alcohol in a solution that contains 24 mL isopropyl alcohol in 1100 mL of water?
Percent by Volume Practice I cont’d
4. What is the percent by volume of 140 mL of isopropyl alcohol dissolved in 60 mL of water?
Percent by Volume Practice I cont’d
5. A bottle of hydrogen peroxide is labeled 3%. If you pour out 50 mL, what volume of hydrogen peroxide have you poured out?
Percent by Volume Practice I cont’d
6. If 50 mL of pure acetone is mixed with 450 mL of water, what is the percent by volume?
Percent by Volume Practice I cont’d
7. If you have 500 mL of a 10% solution of tetracycline, what is the volume of tetracycline and water?
Percent by Volume Practice I cont’d
8. If you pour out 60 mL of a 30% alcohol solution, how much pure alcohol have you poured?
Percent by Mass Practice I
1. What is the % concentration by mass of 8.3 g of NaCl dissolved in 300 g of water? (2.7%)
2. What is the % concentration by mass of 65 g of C6H12O6 dissolved in 500 g of water? (11.5%)
3. You have a 1000 g bleach solution. The % concentration by mass of the solute NaOCl is 6.02 % . How many grams of the NaOCl are in the solution? (60.2 g)
4. How many grams of water would you have to add to 50 g of NaCl to produce a solution concentration of 5%? (950 g) 5. What is the solution concentration by mass of 12 grams of NaCl dissolved in 300 grams of water? (3.8%) 6. If you need to produce 500 grams of an 8.3% saline solution, how many grams of salt and how many grams of water would you use to form the solution? (41.5 g of salt, 458.5 g H2O)
Diluting Solutions• Concentrated stock solutions of chemicals are
purchased in the laboratory because they are much more economical to buy
• These solutions are diluted to desired concentrations that are required by the labs we perform in class
• To properly dilute solutions we use the following equation:
o Where ‘M’ = Molarityo Where ‘V’ = Volume
Diluting Solutions Examples
1. What volume of a 3M KI solution would you use to make .3 L of a 1.25M KI solution? 2. How many milliliters of a 5M H2SO4 solution would you need to prepare 100 mL of .25 M H2SO4?
3. If you dilute 20 mL of a 3.5M solution to make 100 mL of solution, what is the molarity of the dilute solution? 125 mL, 5 mL, .7M
Molarity• concentration expressed as the number of moles
of solute per liter of solution• use M, molar
o ex. 2.5 M solution is a 2.5 molar solution
• Conversion reminder: to convert mL to L, must divide by 1000 (1000 mL = 1 L)
Molarity Equations
Molarity Example Problem #1
What is the molarity of a solution containing 158 grams of sodium chloride, NaCl, in 2.5 liters of water?
Molarity Example Problem #2
Calculate the molarity of 250 mL solution containing 75 grams of H2SO4.
Molarity Example Problem #3
How many grams of NaCl would be dissolved in 1.75 L of a 0.85 M solution of NaCl?