PreLab CalculationsHow Would You Prepare 250 ML Of The Following Solutions:1. Sodium Thiosulfate Solution (0.1 M)2. Sodium Hydroxide ( 0.2 Mol/L 0.2 \, \text{mol/L} 0.2 Mol/L ) (Molar Mass Of $\text{Na}_2\text{S}_2\text{O}_3 \cdot 5 \text{H}_2\text{O} =
Introduction
Preparing solutions of specific concentrations is a crucial step in various chemical experiments. In this article, we will discuss the prelab calculations required to prepare 250 mL of two different solutions: sodium thiosulfate solution (0.1 M) and sodium hydroxide solution (0.2 mol/L). We will use the molar mass of sodium thiosulfate and the given molarity to calculate the required amount of solute and then determine the volume of solvent needed to achieve the desired concentration.
Calculations for Sodium Thiosulfate Solution (0.1 M)
Molar Mass of Sodium Thiosulfate
The molar mass of sodium thiosulfate (Na2S2O3) is calculated as follows:
- Sodium (Na): 22.99 g/mol
- Sulfur (S): 32.07 g/mol
- Oxygen (O): 16.00 g/mol
- Total molar mass of Na2S2O3: 2(22.99) + 2(32.07) + 3(16.00) = 158.19 g/mol
However, the molar mass of Na2S2O3·5H2O is given as 248.18 g/mol.
Calculating the Amount of Solute Required
To prepare 250 mL of 0.1 M sodium thiosulfate solution, we need to calculate the amount of solute required.
- Molarity (M) = moles of solute / liters of solution
- Moles of solute = M x liters of solution
- Moles of solute = 0.1 M x 0.250 L = 0.025 mol
Calculating the Mass of Solute Required
Now, we need to calculate the mass of solute required to achieve the desired number of moles.
- Mass of solute = moles of solute x molar mass
- Mass of solute = 0.025 mol x 248.18 g/mol = 6.2045 g
Calculating the Volume of Solvent Required
Finally, we need to calculate the volume of solvent required to achieve the desired concentration.
- Volume of solvent = volume of solution - volume of solute
- Since the volume of solute is negligible compared to the volume of solution, we can assume that the volume of solvent is equal to the volume of solution.
- Volume of solvent = 250 mL
Calculations for Sodium Hydroxide Solution (0.2 mol/L)
Calculating the Amount of Solute Required
To prepare 250 mL of 0.2 mol/L sodium hydroxide solution, we need to calculate the amount of solute required.
- Molarity (M) = moles of solute / liters of solution
- Moles of solute = M x liters of solution
- Moles of solute = 0.2 mol/L x 0.250 L = 0.05 mol
Calculating the Mass of Solute Required
Now, we need to calculate the mass of solute required to achieve the desired number of moles.
- Molar mass of NaOH = 40.00 g/mol
- Mass of solute = moles of solute x molar mass
- Mass of solute = 0.05 mol x 40.00 g/mol = 2.000 g
Calculating the Volume of Solvent Required
Finally, we need to calculate the volume of solvent required to achieve the desired concentration.
- Volume of solvent = volume of solution - volume of solute
- Since the volume of solute is negligible compared to the volume of solution, we can assume that the volume of solvent is equal to the volume of solution.
- Volume of solvent = 250 mL
Conclusion
In this article, we have discussed the prelab calculations required to prepare 250 mL of two different solutions: sodium thiosulfate solution (0.1 M) and sodium hydroxide solution (0.2 mol/L). We have used the molar mass of sodium thiosulfate and the given molarity to calculate the required amount of solute and then determined the volume of solvent needed to achieve the desired concentration. These calculations are essential in various chemical experiments and should be performed carefully to ensure accurate results.
References
- CRC Handbook of Chemistry and Physics, 97th Edition
- International Union of Pure and Applied Chemistry (IUPAC) Compendium of Chemical Terminology, 2nd Edition
Note
Introduction
Preparing solutions of specific concentrations is a crucial step in various chemical experiments. In this article, we will discuss the prelab calculations required to prepare 250 mL of two different solutions: sodium thiosulfate solution (0.1 M) and sodium hydroxide solution (0.2 mol/L). We will also address some frequently asked questions related to prelab calculations.
Q&A
Q: What is the difference between molarity and molality?
A: Molarity is the number of moles of solute per liter of solution, while molality is the number of moles of solute per kilogram of solvent.
Q: How do I calculate the amount of solute required for a solution?
A: To calculate the amount of solute required, you need to multiply the molarity of the solution by the volume of the solution in liters.
Q: What is the significance of the molar mass of a substance?
A: The molar mass of a substance is the mass of one mole of that substance. It is used to calculate the amount of solute required for a solution.
Q: How do I calculate the volume of solvent required for a solution?
A: To calculate the volume of solvent required, you need to subtract the volume of the solute from the total volume of the solution.
Q: What is the difference between a strong acid and a weak acid?
A: A strong acid is an acid that completely dissociates in water, while a weak acid is an acid that only partially dissociates in water.
Q: How do I prepare a solution of a specific concentration?
A: To prepare a solution of a specific concentration, you need to calculate the amount of solute required and then add it to the solvent.
Q: What is the importance of prelab calculations in chemistry?
A: Prelab calculations are essential in chemistry as they help to ensure that the solutions prepared are of the correct concentration and that the experiments are conducted safely and accurately.
Q: How do I verify the concentration of a solution?
A: To verify the concentration of a solution, you can use various methods such as titration, spectrophotometry, or chromatography.
Q: What are some common mistakes to avoid when preparing solutions?
A: Some common mistakes to avoid when preparing solutions include incorrect calculations, incorrect measurement of solute and solvent, and contamination of the solution.
Conclusion
In this article, we have discussed the prelab calculations required to prepare 250 mL of two different solutions: sodium thiosulfate solution (0.1 M) and sodium hydroxide solution (0.2 mol/L). We have also addressed some frequently asked questions related to prelab calculations. These calculations are essential in various chemical experiments and should be performed carefully to ensure accurate results.
References
- CRC Handbook of Chemistry and Physics, 97th Edition
- International Union of Pure and Applied Chemistry (IUPAC) Compendium of Chemical Terminology, 2nd Edition
Note
The calculations presented in this article are for illustrative purposes only and should not be used for actual laboratory work without proper validation and verification.