Lab Molarity
Welcome to your "sort of" first online lab. I would like to use this first lab activity to cover some additional lecture material and then follow it up with a short activity.
Section 4.5: Concentration of Solutions
You may have noticed in lab that many of the solutions we used had a label like "3M" to indicate the concentration of the solute in the solution. 3M means 3 molar or the molarity is 3. As you will see in your text the definition of molarity (M) is the moles of solute divided by liters of solution.
Example 1
- What is the molarity of a solution made by adding 1.23 moles of sodium chloride to 1 .00 L of water?
- <write this out>
Answer: 1.23 M NaCl
Example 2
- What is the molarity of a solution made by adding 12.34 grams of sodium chloride to 1.000 L of water? (Note: you will need to calculate the molecular mass of NaCl...)
- <write this out>
- molecular mass of NaCl...
- 12.34 g of NaCl = ? moles of NaCl
- then calculate M = ?
Answer: 0.2112 M NaCl
Hard (but not really) Example
- What is the molarity of a solution made by adding 43.21 grams of sodium chloride to 1,234 mL of water?
- <write this out>
Answer: 0.5992 M NaCl