Calculate the mass (g) of solutes needed to prepare 25 mL of each 0.50 M solution KOH

To calculate the mass of solute (KOH) needed to prepare 25 mL of a 0.50 M solution, we can follow these steps:

### 1. Calculate moles of KOH required:

First, use the formula for molarity (M):

\[
\text{Molarity (M)} = \frac{\text{moles of solute}}{\text{volume of solution in liters (L)}}
\]

Rearranging to find the moles of solute:

\[
\text{moles of KOH} = \text{Molarity} \times \text{Volume in liters}
\]

Given:
- Molarity (M) = 0.50 M
- Volume = 25 mL = 0.025 L (since 1 L = 1000 mL)

\[
\text{moles of KOH} = 0.50 \times 0.025 = 0.0125 \text{ moles}
\]

### 2. Convert moles to grams:

Now, use the molar mass of KOH to convert moles to grams. The molar mass of KOH is calculated as follows:
- Potassium (K) = 39.1 g/mol
- Oxygen (O) = 16.0 g/mol
- Hydrogen (H) = 1.0 g/mol

\[
\text{Molar mass of KOH} = 39.1 + 16.0 + 1.0 = 56.1 \text{ g/mol}
\]

Now, calculate the mass:

\[
\text{Mass of KOH} = \text{moles of KOH} \times \text{molar mass of KOH}
\]

\[
\text{Mass of KOH} = 0.0125 \times 56.1 = 0.70125 \text{ g}
\]

### Final Answer:
The mass of KOH required to prepare 25 mL of a 0.50 M solution is **0.701 g**.

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Would you like any additional details or have any questions?

### Related Questions:
1. How would the mass change if the molarity of the solution was 1.0 M instead of 0.50 M?
2. How can you calculate the molarity of a solution if you only know the mass and volume?
3. What steps are involved in preparing the solution after calculating the mass?
4. How does the temperature affect the solubility of KOH in water?
5. What are the safety precautions for handling potassium hydroxide (KOH) in a lab setting?

### Tip:
Always make sure to double-check your unit conversions, especially when dealing with volumes in milliliters and liters.

Calculate the mass (g) of solutes needed to prepare 25 mL of each 0.50 M solution KOH.

Learn how to calculate the mass of KOH needed to prepare a 25 mL solution with a concentration of 0.50 M. This step-by-step solution covers key chemistry concepts such as molarity, stoichiometry, and unit conversions. Suitable for students in Grades 9-12.

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