It looks like you've uploaded an image of a worksheet titled
"Percent by Mass and Molarity Worksheet", which contains several problems related to calculating percent by mass and molarity in chemistry. Since I can't view images directly, I’ll need you to provide the text or describe the specific problems from the worksheet so I can help solve them.
However, based on the title and typical content of such worksheets, here’s a general guide on how to solve common types of problems:
---
🔬 1. Percent by Mass (Mass Percent)
Formula:
\[
\text{Percent by mass} = \left( \frac{\text{mass of solute}}{\text{mass of solution}} \right) \times 100\%
\]
Where:
-
Mass of solution = mass of solute + mass of solvent
Example Problem:
> What is the percent by mass of 5.0 g of salt dissolved in 95.0 g of water?
Solution:
\[
\text{Mass of solution} = 5.0\, \text{g} + 95.0\, \text{g} = 100.0\, \text{g}
\]
\[
\text{Percent by mass} = \left( \frac{5.0}{100.0} \right) \times 100\% = 5.0\%
\]
---
🔬 2. Molarity (M)
Formula:
\[
\text{Molarity (M)} = \frac{\text{moles of solute}}{\text{liters of solution}}
\]
Steps:
1. Convert grams of solute to moles using molar mass.
2. Divide moles by volume in liters.
Example Problem:
> What is the molarity of a solution made by dissolving 20.0 g of NaOH in enough water to make 500 mL of solution?
Solution:
- Molar mass of NaOH = 23 + 16 + 1 = 40 g/mol
- Moles of NaOH = \( \frac{20.0\, \text{g}}{40\, \text{g/mol}} = 0.50\, \text{mol} \)
- Volume = 500 mL = 0.500 L
- Molarity = \( \frac{0.50\, \text{mol}}{0.500\, \text{L}} = 1.0\, \text{M} \)
---
🔍 Common Types of Problems on Such Worksheets:
1.
Find percent by mass given masses of solute and solvent.
2.
Find molarity given mass of solute and volume of solution.
3.
Convert between molarity and mass using stoichiometry.
4.
Dilution problems using \( M_1V_1 = M_2V_2 \).
5.
Finding mass of solute needed for a desired concentration.
---
✔ To help you specifically:
Please
type out the problems from the worksheet, or describe what each question asks. For example:
- "What is the percent by mass of 10 g sugar in 90 g water?"
- "Calculate the molarity of 25 g KCl in 250 mL of solution."
Once I know the exact questions, I can solve them step-by-step and explain the reasoning clearly.
Let me know!
Parent Tip: Review the logic above to help your child master the concept of percent by mass worksheet.
