Download Molarity Molality Lab

Chemistry Ch. 12 Lab; Molarity & Molality
Name ______________________________ Per _________
Define Concentration:
Being very specific, write the definitions of these by writing the symbol and fraction for each:
Molarity
molality
mass %
Activity 1: Finding the Molarity and the molality of a solution Find the Molarity of the
NaCl solution at your station by designing an experiment to figure it out. Use about 35 to 50 mL
of the salt solution in your experiment. Take all necessary measurements before you begin the
experiment. After this experiment is underway, continue on with the lab and come back to fill in
the data when it’s done. Here’s where you can record some data:
Mass of solution
Mass of empty beaker
Your choice__________
Your choice _________
What two things did you measure to find the Molarity? (ie: no tool measures “moles”)
What’s the Molarity of the salt solution?
What two things did you measure to find the molality? (moles are not measured)
What’s the one thing you found mathematically (not by measuring; you subtracted to get it)?
What’s the molality of the salt solution?
Ch. 12 Lab; Molarity & molality
molality
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Activity 2: A Closer Look at Vinegar, an Acetic Acid solution.
Vinegar’s active ingredient is acetic acid, which can be written as CH3COOH or simply as
“hydrogen acetate.” Write the formula for “hydrogen acetate” using your reference sheet.
Use those charges! (oxidation #’s)
Product ingredient concentrations are most often written in mass percents. Find the
concentration of the acetic acid, as listed on the bottle of vinegar. If you had 100 grams of
vinegar, being very specific, write out what this means as a fraction with numbers and specific
units. There should be a plus sign and two things on the bottom of the fraction.
The density of vinegar is just about the same as water, or 1.0 grams per 1.0 mL of solution.
Starting with your specific concentration with units, listed in the last box, use D.A. to convert this
over to find the Molarity of the vinegar.
Your D.A.
Molarity of Vinegar
Activity 3: Making a 0.04 Molar (0.04 Molarity) Solution
Make 250. mL of 0.04 M sucrose (C12H22O11) solution in a volumetric flask (mass it empty first).
Show your calculations
grams of sugar used
Mass of solution:
Activity 4: How many grams of solute are in each flask?
Go look at the two flasks of copper sulfate solution. Calculate how many grams of copper
sulfate are in each flask. Show your D.A. with units.
Flask 1 D.A.
grams of copper sulfate
Flask 2 D.A.
grams of copper sulfate
Ch. 12 Lab; Molarity & molality
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Ch. 12 Lab; Molarity & molality
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