How would you prepare 250 mL of a 10% (w/v) KCl solution? (KCl=74.6 g/mol)
Well, to prepare a 10% KCl solution, let's start with a joke. Why did the scarecrow win an award? Because he was outstanding in his field! Now, back to the question.
To make a 10% (w/v) KCl solution, you'll need 10% of KCl in 250 mL. Since the concentration is given as a weight/volume percentage, it means that you'll have 10 grams of KCl dissolved in a total volume of 250 mL.
So, grab your clown-sized laboratory coat and measure 10 grams of KCl using a scale. Then, add it to a container and pour in 250 mL of water. Give it a good mix, and voila! You've got yourself a 10% KCl solution. Just make sure not to accidentally use it to season your food instead of salt, unless you're a fan of salty jokes!
To prepare 250 mL of a 10% (w/v) KCl solution, you will need to follow these steps:
Step 1: Determine the amount of KCl needed:
To calculate the amount of KCl needed, we first need to determine the mass of KCl in grams required to make a 10% (w/v) solution.
The formula for weight per volume percent concentration is:
% (w/v) = (mass of solute / volume of solvent) x 100
Given:
Desired volume of solution (V) = 250 mL (or 0.25 L)
Desired weight per volume percent concentration (%w/v) = 10%
Let's rearrange the formula to calculate the mass of KCl:
mass of solute = % (w/v) x volume of solvent / 100
mass of solute = 10% x 0.25 L / 100
Step 2: Calculate the mass of KCl:
mass of solute = 0.10 x 0.25 L = 0.025 L
Step 3: Convert the volume of the solution to grams:
The density of water is approximately 1 g/mL, so 250 mL of water is equivalent to 250 g.
Step 4: Dissolve the KCl:
Weigh out the calculated mass of KCl (0.025 g) using an analytical balance.
Step 5: Add water to the KCl:
Transfer the weighed KCl to a suitable container (e.g., beaker or flask) and add water gradually while stirring until the final volume reaches 250 mL.
Step 6: Mix well:
Ensure that the KCl is fully dissolved in the water by stirring until it is completely mixed.
Step 7: Label and store:
Label the container with the contents, concentration, and date of preparation. Store the solution in a suitable container and location.
And that's it! You have prepared 250 mL of a 10% (w/v) KCl solution.
To prepare a 10% (w/v) KCl solution, you need to determine the mass of KCl needed and then dissolve it in a solvent (usually water) to obtain a total volume of 250 mL.
The formula to calculate the mass of solute is:
Mass = (Percent/100) x Volume x Density
In this case, the percent is 10%, the volume is 250 mL, and the density of KCl is not required since it is being dissolved in water. The density of water is approximately 1 g/mL, which is close enough for this calculation.
Substituting the values into the formula:
Mass = (10/100) x 250 mL x 1 g/mL
Mass = 25 g
Therefore, you would need 25 grams of KCl to prepare a 10% (w/v) solution.
To actually prepare the solution:
1. Measure out 25 grams of KCl using a balance.
2. Dissolve the KCl in a suitable amount of water (less than 250 mL).
3. Transfer the solution to a 250 mL volumetric flask.
4. Add water to the flask until the total volume reaches 250 mL, ensuring thorough mixing.
Now you have successfully prepared a 250 mL 10% (w/v) KCl solution.
10% (w/v) KCl solution=0.10= x g of KCl/250mL
Solving for x g of KCl:
x g of KCl=0.10*250ml=25g of KCl
Add to 250mL to flask and make to volume.