For an experiment, a student needs 1L each of 2M NaOH and 2 M KCl solutions. The NaOH will be prepared from a 12M stock solution, whereas the KCl will be prepared from dry, powder,KCl. Describe the process by which each of the solutions can be prepared.
Include:
Mention of correct materials needed
Description of calculations using the formula for molarity
Description of lab procedures
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To prepare the 2M NaOH solution:
Materials needed:
- 12M NaOH stock solution
- Distilled water
- 1L volumetric flask
- Pipette or graduated cylinder
- Stirring rod or magnetic stirrer
Procedure:
1. Calculate the amount of 12M NaOH stock solution required to prepare 1L of 2M NaOH solution using the formula for molarity:
M1V1 = M2V2
Here, M1 is the initial molarity (12M), V1 is the initial volume (unknown), M2 is the final molarity (2M), and V2 is the final volume (1L).
Rearranging the equation, V1 = (M2V2) / M1
Substituting the values, V1 = (2M * 1L) / 12M = 0.167L (167mL)
2. Measure 167mL of the 12M NaOH stock solution using a pipette or graduated cylinder.
3. Transfer the measured 167mL of the stock solution to a 1L volumetric flask.
4. Add distilled water to the flask, while stirring, to make the total volume reach 1L.
5. Continue stirring until the NaOH is completely dissolved in the water.
To prepare the 2M KCl solution:
Materials needed:
- Dry KCl powder
- Distilled water
- Weighing scale
- 1L volumetric flask
- Stirring rod or magnetic stirrer
Procedure:
1. Calculate the amount of KCl powder needed to prepare 1L of 2M KCl solution using the formula for molarity:
M1V1 = M2V2
Here, M1 is the initial molarity (unknown), V1 is the initial volume (unknown), M2 is the final molarity (2M), and V2 is the final volume (1L).
Rearranging the equation, M1 = (M2V2) / V1
Since the KCl powder is in solid form, the volume (V1) will be the same as the final volume since no additional dilution is required.
Substituting the values, M1 = (2M * 1L) / 1L = 2M
2. Weigh out 186.56 grams of dry KCl powder on a weighing scale. This is the molar mass of KCl.
3. Transfer the weighed KCl powder to a 1L volumetric flask.
4. Add distilled water to the flask, while stirring, to make the total volume reach 1L.
5. Continue stirring until the KCl is completely dissolved in the water.
Note: Throughout the process, it is important to wear appropriate safety gear such as gloves and goggles.