Matter as Solutions Acids and Bases Dilution Chemistry 20 Dilution A standard solution is any solution whose concentration is accurately known Dilution involves the addition of solvent to a solution in order to decrease its concentration ID: 536162
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Slide1
Chemistry 20 – Unit 3
Matter as Solutions, Acids and BasesSlide2
Dilution
Chemistry 20Slide3
Dilution
A
standard solution
is any solution whose concentration is accurately known
.
Dilution
involves the addition of solvent to a solution in order to decrease its concentration
.
For aqueous solutions, water is added to dilute the solution. This increases the overall volume without affecting the amount of dissolved solute.Slide4
Dilution
Since the amount of solute remains constant throughout dilution, the following relationship exists:
Slide5
Standard Solutions
The
stock solution
is the more concentrated solution that is being diluted. It is generally a standard solution
.
By diluting a solution carefully and with accurate measurements, the dilute solution will also be a standard solution.Slide6
Example
300 mL of water is added to 17.2 mL of 5.14
mol
/L
HBr
(
aq
). Calculate the resulting concentration.Slide7
Example
300 mL of water is added to 17.2 mL of 5.14
mol
/L
HBr
(
aq
). Calculate the resulting concentration.0.278 mol/LSlide8
Example
For a class experiment, a teacher must prepare 1.00 L of 0.170
mol
/L sulfuric acid, H
2
SO
4(
aq). This acid is usually sold as a 17.8 mol/L concentrated solution. How much of the concentrated solution should be used to make a new solution with the correct concentration?Slide9
Example
For a class experiment, a teacher must prepare 1.00 L of 0.170
mol
/L sulfuric acid, H
2
SO
4(
aq). This acid is usually sold as a 17.8 mol/L concentrated solution. How much of the concentrated solution should be used to make a new solution with the correct concentration?9.55 mLSlide10
Example
30.0 mL of a stock solution of CaCl
2(
aq
)
is diluted to a total volume of 500.0
mL.
The dilute solution is analyzed and found to have a concentration of 15.8 mmol/L. What was the molarity of the stock solution?Slide11
Example
30.0 mL of a stock solution of CaCl
2(
aq
)
is diluted to a total volume of 500.0
mL.
The dilute solution is analyzed and found to have a concentration of 15.8 mmol/L. What was the molarity of the stock solution?0.263 mol/LSlide12
Preparing Standard Solutions
The two common ways of preparing a standard solution include:
dissolving
a measured mass of pure solute in a certain volume of solution
diluting
a stock solution by adding a known volume of solventSlide13
When dissolving a measured mass of pure solute, the steps to follow are:
Calculate
the mass of solute that will need to be measured out.
Measure
out this mass of solute accurately with an electronic balance.
Dissolve
the solute in a minimum volume of water.
Transfer solution into a volumetric flask that is half-filled with water.Fill the volumetric flask with water up to the calibration line.Stopper the flask and mix the solution. http://www.youtube.com/watch?v=XMtm4hVCGWgSlide14
Example
How would a 0.180
mol
/L solution of lithium nitrate be properly prepared by dissolving the solid chemical?Slide15
Example
How would a 0.180
mol
/L solution of lithium nitrate be properly prepared by dissolving the solid chemical
?
mass of LiNO
3
= 12.411 g Slide16
When diluting a stock solution, the steps to follow are:
Calculate
the volume of stock solution that will need to be measured.
Measure
out this volume of solution accurately with a pipette.
Transfer
solution into a volumetric flask that is half-filled with water.
Fill the volumetric flask with water up to the calibration line.Stopper the flask and mix the solution.http://www.youtube.com/watch?v=kMDC4vNEoVoSlide17
Example
How would a 0.220
mol
/L solution of acetic acid be properly prepared by dilution of a 3.50
mol
/L stock solution?Slide18
Example
How would a 0.220
mol
/L solution of acetic acid be properly prepared by dilution of a 3.50
mol
/L stock solution
?
62.9 mLSlide19
Homework
Dilution and Standard Solutions Practice Questions
Solutions Quiz Wednesday