Describe how to make 20 mL of a 6.0 % solution from a stock solution with a concentration of 10 %.
To make a 20 mL 6.0% solution from a stock solution with a concentration of 10%, you will need to calculate the volume of the stock solution and the volume of the solvent needed.
The percent concentration refers to the amount of solute (in this case, the stock solution) present in the total solution volume. Here's how to calculate the amount of stock solution and solvent needed:
1. Determine the amount of solute (stock solution) needed:
Given that the final solution volume is 20 mL and the desired concentration is 6.0%, we can calculate the amount of stock solution needed as follows:
Stock solution volume = (desired concentration / stock concentration) × final volume
Stock solution volume = (6.0% / 10%) × 20 mL
Stock solution volume = 0.6 × 20 mL
Stock solution volume = 12 mL
So, you will need 12 mL of the stock solution.
2. Determine the amount of solvent needed:
The solvent is the liquid used to dilute the stock solution to achieve the desired concentration. To calculate the amount of solvent needed, subtract the volume of the stock solution from the final volume:
Solvent volume = final volume - stock solution volume
Solvent volume = 20 mL - 12 mL
Solvent volume = 8 mL
So, you will need 8 mL of solvent. This can be water or any other appropriate solvent.
To prepare the 20 mL 6.0% solution from the stock solution:
- Measure 12 mL of the 10% stock solution using a graduated cylinder.
- Pour the measured stock solution into a container or beaker.
- Measure 8 mL of the chosen solvent using a separate graduated cylinder.
- Slowly add the measured solvent to the container or beaker containing the stock solution.
- Mix the solution gently to ensure thorough mixing.
Now, you have successfully prepared a 20 mL 6.0% solution using a stock solution with a concentration of 10%.