Concentration of Solutions
Concentration of Solutions
Concentration of Solutions
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Name Class Date<br />
Problem Solving continued<br />
Sample Problem 2<br />
What is the molarity <strong>of</strong> a solution prepared by dissolving 37.94 g <strong>of</strong><br />
potassium hydroxide in some water and then diluting the solution to a<br />
volume <strong>of</strong> 500.00 mL?<br />
Solution<br />
ANALYZE<br />
What is given in the problem?<br />
What are you asked to find?<br />
the mass <strong>of</strong> the solute, KOH, and the final volume<br />
<strong>of</strong> the solution<br />
the concentration <strong>of</strong> the solution expressed as<br />
molarity<br />
Items<br />
Mass <strong>of</strong> solute<br />
Moles <strong>of</strong> solute<br />
Molar mass <strong>of</strong> solute*<br />
Volume <strong>of</strong> solution<br />
<strong>Concentration</strong> (molarity)<br />
Data<br />
37.94 g KOH<br />
? mol KOH<br />
56.11 g/mol<br />
500.00 mL<br />
? M<br />
* determined from the periodic table<br />
PLAN<br />
What steps are needed to calculate the concentration <strong>of</strong> the solution as molarity?<br />
Determine the amount in moles <strong>of</strong> solute; calculate the moles per liter <strong>of</strong> solution.<br />
1<br />
Mass <strong>of</strong> KOH<br />
in g<br />
multiply by the<br />
inverted molar<br />
mass <strong>of</strong> KOH<br />
Volume <strong>of</strong> KOH<br />
solution in mL<br />
multiply by the<br />
conversion factor<br />
1 L<br />
1000 mL<br />
2<br />
Amount <strong>of</strong> KOH<br />
in mol<br />
moles solute<br />
M liter solution<br />
4<br />
Molarity <strong>of</strong> KOH<br />
solution<br />
3<br />
Volume <strong>of</strong> KOH<br />
solution in L<br />
1<br />
molar mass <strong>of</strong> KOH<br />
given 1 mol KOH mol KOH<br />
g KOH 56.11 g KOH<br />
Copyright © by Holt, Rinehart and Winston. All rights reserved.<br />
Holt ChemFile: Problem-Solving Workbook 201 <strong>Concentration</strong> <strong>of</strong> <strong>Solutions</strong>
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