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Questions and Answers
What is the primary purpose of preparing stock solutions?
What is the primary purpose of preparing stock solutions?
What is the formula to calculate the volume of stock solution needed for dilution?
What is the formula to calculate the volume of stock solution needed for dilution?
What is the concentration of a solution if 10 mL of a 5M stock solution is diluted to 50 mL?
What is the concentration of a solution if 10 mL of a 5M stock solution is diluted to 50 mL?
What is the unit of measurement for molarity?
What is the unit of measurement for molarity?
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If you have a 3M stock solution of NaCl and want to make 200 mL of a 1.5M solution, how much stock solution do you need?
If you have a 3M stock solution of NaCl and want to make 200 mL of a 1.5M solution, how much stock solution do you need?
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What is the formula to calculate the molarity of a solution?
What is the formula to calculate the molarity of a solution?
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Study Notes
Stock Solutions
- A stock solution is a concentrated solution of a known solute, used to prepare multiple diluted solutions
- Stock solutions are typically prepared at a high concentration to minimize storage volume and facilitate convenient dilution
- Common stock solution concentrations:
- 1M (1 mole/L)
- 0.1M (0.1 moles/L)
- 10% (10 grams/100 mL)
Concentration Calculations
-
Molarity (M) Calculations
- Molarity (M) = moles of solute / liters of solution
- M1V1 = M2V2 (dilution formula, where M1 and V1 are initial concentration and volume, and M2 and V2 are final concentration and volume)
-
Dilution Calculations
- To dilute a solution:
- Calculate the volume of stock solution needed: V1 = (M2V2) / M1
- Add the calculated volume of stock solution to enough solvent to make the desired final volume (V2)
- To dilute a solution:
-
Example Problems
- If you have a 2M stock solution of NaCl and want to make 100 mL of a 0.5M solution, how much stock solution do you need?
- V1 = (0.5M × 100 mL) / 2M = 25 mL of stock solution
- If you want to dilute 10 mL of a 5M stock solution to 50 mL, what will be the final concentration?
- M2 = M1 × (V1 / V2) = 5M × (10 mL / 50 mL) = 1M
- If you have a 2M stock solution of NaCl and want to make 100 mL of a 0.5M solution, how much stock solution do you need?
Stock Solutions
- A stock solution is a concentrated solution of a known solute, used to prepare multiple diluted solutions.
- Stock solutions are prepared at a high concentration to minimize storage volume and facilitate convenient dilution.
- Common stock solution concentrations include 1M (1 mole/L), 0.1M (0.1 moles/L), and 10% (10 grams/100 mL).
Concentration Calculations
Molarity (M) Calculations
- Molarity (M) is calculated by dividing the number of moles of solute by the number of liters of solution.
- The dilution formula is M1V1 = M2V2, where M1 and V1 are initial concentration and volume, and M2 and V2 are final concentration and volume.
Dilution Calculations
- To dilute a solution, calculate the volume of stock solution needed using the formula V1 = (M2V2) / M1.
- Add the calculated volume of stock solution to enough solvent to make the desired final volume (V2).
Example Problems
- To make 100 mL of a 0.5M solution from a 2M stock solution of NaCl, 25 mL of stock solution are needed.
- If 10 mL of a 5M stock solution are diluted to 50 mL, the final concentration will be 1M.
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Description
Learn about stock solutions, their concentrations, and how to calculate molarity and perform dilution calculations in chemistry.