solution concentration (molarity)
Post on 20-Jan-2016
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a measure of the amount of solute that is dissolved in a given quantity of solvent
unit of measurement is Molarity (M) which is moles/liter
can be dilute or concentrated
The number of moles of solute dissolved in one liter of solution
Molarity = moles soluteliters of solution
1.0 L of water was used to make 1.0 L of solution. Notice 1.0 L of water was used to make 1.0 L of solution. Notice the water left over. 1.0L of water would be too much.the water left over. 1.0L of water would be too much.
top off to 1 liter
Step 1: Calculate moles of NiCl2• 6H2O in 5 g of NiCl2• 6H2O
5.00 g • 1 mol
237.7 g = 0.0210 mol
0.0210 mol0.250 L
= 0.0841 M
Step 2: Calculate Molarity
1.0 L = 1000 mL .25 L = 250 mL
Step 1: Step 1: Change mL to L.Change mL to L.
250 mL/1000 = 0.250 L250 mL/1000 = 0.250 L
Step 2: Step 2: Calculate.Calculate.
moles = (0.0500 M) (0.250 L) = 0.0125 moles Hmoles = (0.0500 M) (0.250 L) = 0.0125 moles H22CC22OO44
Step 3: Step 3: Convert moles to grams.Convert moles to grams.
(0.0125 mol H(0.0125 mol H22CC22OO44) ) ((90.00 g90.00 g) ) = = 1.13 g1.13 g 1 mol H1 mol H22CC22OO44
M = moles/V M = moles/V moles = M•V moles = M•V
What mass of oxalic acid, H2C2O4, is required to make 250 mL of a 0.0500 M solution?
How many grams of NaOH are required to prepare 400 mL of 3.0 M NaOH solution?
1) 12 g2) 48 g3) 300 g
diluting a solution reduces the number of moles of solute per unit volume, but the total number of moles of solute in the solution does not change
therefore, as Volume increases, Molarity decreases
Molarity (M) = moles of soluteliters of solution (V)
becomes: M1 V1 = M2 V2
M1 V1 = M2
V2
lead
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another way to quantitatively describe the concentration of a solution (two ways):the ratio of the volume of the solute to the
volume of the solution % V = volume of solute / volume of solution x
100%85 mL of ethanol diluted with water to a total
solution volume of 250mL 85 mL/250 mL (100%) = 34% ethanol by
volumethe ratio of the mass of the solute to the mass of
the solution% M = mass of solute / mass of solution x 100%
56 g NaCl in a 2000 g NaCl solution56g/2000g (100%) = 2.8% salt by mass
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