To make a concentrated or dilute solution from a pure substance like NaCl or KI, you need to add a certain amount of the substance to a solvent, usually water, and adjust the concentration accordingly. Here's how you can make both concentrated and dilute solutions:
Concentrated Solution:
- Determine the desired concentration of the solution. Concentration is usually expressed in terms of a percentage (% w/v) or molarity (moles per liter, M).
- Weigh the required amount of the pure substance using a balance. For example, if you want to make a 10% w/v solution of NaCl with 100 mL of water, you need to calculate 10% of the total volume (10% of 100 mL = 10 g NaCl).
- Add the weighed amount of the pure substance to a container or beaker.
- Slowly add the solvent (e.g., water) to the container while stirring continuously until the substance is completely dissolved. This may require gentle heating or additional agitation depending on the substance.
- Once all the solid has dissolved, the concentrated solution is ready. Ensure thorough mixing to obtain a homogenous solution.
Dilute Solution:
- Determine the desired concentration of the solution, usually given as a percentage (% w/v) or molarity (M).
- Calculate the amount of pure substance needed based on the desired final volume of the solution. For example, if you want to make a 0.1 M solution of KI with a final volume of 500 mL, you need to calculate the moles of KI required (0.1 M x 0.5 L = 0.05 moles KI).
- Weigh the required amount of the pure substance using a balance.
- Dissolve the substance in a small volume of the solvent (water) in a container or beaker, ensuring complete dissolution.
- Gradually add the remaining solvent (water) to reach the desired final volume while stirring continuously.
- Once the dilution is complete, mix the solution thoroughly to ensure uniformity.
Remember to handle pure substances and solutions carefully, following proper safety precautions and protocols.