Download - How to mix a Standard Solution
How to mix a Standard Solution
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 480
Process of Making a Standard Solution from Liquids
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 483
Markings on Glassware
TC 20oC “to contain at a temperature of 20 oC”
TD “to deliver” Ts “time in seconds”22
500 mL + 5% Range = 500 mL + 25 mL 475 – 525 mL
Beaker
Graduated Cylinder
Volumetric Flask 500 mL + 0.2 mL Range = 499.8 – 500.2 mL
Concentration…a measure of solute-to-solvent ratio
concentrated dilute “lots of solute” “not much solute”
“watery”
Add water to dilute a solution; boil water off to concentrate it.
Lmol
M
mol
L M
A. mass % = mass of solute mass of sol’n
B. parts per million (ppm) also, ppb and ppt-- commonly used for minerals or contaminants in water supplies
C. molarity (M) = moles of solute L of sol’n
-- used most often in this class
D. molality (m) = moles of solutekg of solvent
KCl m 3.30 L 2.38kg 7.85
nsol' L
solute kg m
112212 OHC m 0.055 L 0.450kg 0.0248
nsol' L
solute kg m
7.85 kg KCl are dissolved in 2.38 L of solution.
Find molality.
24.8 g table sugar (i.e., sucrose, C12H22O11) are mixed into 450 g
water. Find molality.
WRONG
mol 1culem' 10 x6.02
g 18mol 1
mL 1g 1
L 1mL 1000
L 1000 OH culem'X 23
2
OH culem' 10 x3.34F atomsX
OH culem' 1,000,000
F atom 1.5
228
2
222222 CaFc m' 10 x2.505
F at. 2CaFc m' 1
times F at. 10 x5.01 X
22322
2 CaF g 3.25 mol 1
g 78.1
cm' 10 x6.02mol 1
c m' 10 x2.505 CaF gX
What mass of CaF2 must be added to 1,000 L of water
so that fluoride atoms are present at a conc. of 1.5 ppm?
= 3.34 x 1028 m’cules H2O
NaOH g 135 mol 1
g 40.0 mol 3.38 NaOH g X
243243 )(POMg g 889 mol 1
g 262.9 mol 3.38 )(POMg g X
How many moles solute are required to make 1.35 L of 2.50 M solution?
mol = M L = 2.50 M (1.35 L) =
B. What mass magnesium phosphate is this?
A. What mass sodium hydroxide is this?
mol
L M
3.38 mol
Ba(OH) M 0.061 L 5.65
Ba(OH) g 171.3Ba(OH) mol 1
Ba(OH) g 6.58
M X 22
22
Find molarity if 58.6 g barium hydroxide are in 5.65 L solution.
mL 76.3 L 1mL 1000
L 0.763 M 0.140
g 101.1mol 1
KNO g 8.10
L X3
You have 10.8 g potassium nitrate. How many mL of solution will make this a 0.14 M solution?
convert to mL
ConcentrationConcentration
The amount of solute in a solution.
Describing Concentration
• % by mass - medicated creams
• % by volume - rubbing alcohol
• ppm, ppb - water contaminants
• molarity - used by chemists
• molality - used by chemists
MolalityMolality
solvent ofkg
solute of moles(m)molality
mass of solvent only
1 kg water = 1 L waterkg 1
mol0.25 0.25m
http://www.unit5.org/christjs/tempT27dFields-Jeff/
Solutions1.htm
Molarity of Solutions
Molarity of Solutions
Molarity of Solutions