Preparation of Stock Solutions
A. Experiments
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Experiment 1: Preparation of 10% w/v Calcium Carbonate Solution
- Procedure:
- A 10% w/v solution of calcium carbonate (CaCO₃) was prepared by weighing out 10 grams of solid CaCO₃ and dissolving it in enough distilled water to reach a final volume of 100 ml in a 100 ml beaker.
- The solution was then used to fill a 10 ml volumetric flask, ensuring the volume was made up to the calibration mark with distilled water to achieve a final concentration of 10% w/v in the volumetric flask.
- Procedure:
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Experiment 2: Preparation of 500 ppm Calcium Carbonate Solution
- Procedure:
- To prepare a 500 ppm CaCO₃ solution, 0.5 grams of solid CaCO₃ was weighed and dissolved in distilled water in a 250 ml beaker until the total volume reached 100 ml.
- After thorough mixing, the solution was transferred to a 250 ml volumetric flask and the volume was made up to the calibration mark with distilled water to achieve a concentration of 500 ppm.
- Procedure:
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Experiment 3: Preparation of 1% w/v Sodium Ion Solution from Sodium Carbonate
- Procedure:
- For the preparation of a 1% w/v Na⁺ solution, 2.5 grams of sodium carbonate (Na₂CO₃) was dissolved in distilled water in a 250 ml beaker until reaching a total volume of 200 ml.
- After mixing, the solution was transferred to a 250 ml volumetric flask, and the volume was adjusted to the calibration mark with distilled water to ensure a final 1% w/v Na⁺ concentration.
- Procedure:
B. Calculations
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Experiment 1 Calculation:
- The concentration of the prepared solution is given by: \[ \text{Concentration (g/ml)} = \frac{\text{mass of solute (g)}}{\text{volume of solution (ml)}} \] \[ = \frac{10 \text{ g}}{100 \text{ ml}} = 0.1 \text{ g/ml} = 10% \text{ w/v} \]
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Experiment 2 Calculation:
- Concentration in ppm is calculated as: \[ \text{Concentration (ppm)} = \frac{\text{mass of solute (g)}}{\text{volume of solution (L)}} \times 10^6 \] \[ = \frac{0.5 \text{ g}}{0.1 \text{ L}} \times 10^6 = 5000 \text{ ppm} \]
- Upon dilution to 250 ml: \[ \text{Final Concentration (ppm)} = \frac{5000 \text{ ppm} \times 0.1\text{ L}}{0.25\text{ L}} = 500 \text{ ppm} \]
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Experiment 3 Calculation [1% w/v Sodium Ion Solution]:
- \[ \text{Final Concentration (g/ml)} = \frac{2.5 \text{ g}}{250 \text{ ml}} = 0.01 \text{ g/ml} = 1% \text{ w/v} \]
Results
| Experiment | Measured Concentration | Calculated Concentration | |------------|------------------------------------|------------------------------------| | 1 | 10% w/v (0.1 g/ml) | 10% w/v (0.1 g/ml) | | 2 | 500 ppm | 500 ppm | | 3 | 1% w/v (0.01 g/ml) | 1% w/v (0.01 g/ml) |
Discussion
The results obtained from the experiments demonstrated successful preparation of the desired concentrations of calcium carbonate and sodium ion solutions.
- The preparation of the 10% w/v CaCO₃ solution corroborated the method outlined in standard laboratory practices by utilizing proper weighing and mixing techniques (Smith et al., 2020).
- The dilution factors involved in the preparation of the 500 ppm solution highlighted essential concepts of concentration and dilution, affirming that concentration decreases proportionally with increased volume (Brown et al., 2021).
- The preparation of a 1% w/v Na⁺ solution from sodium carbonate aligned with recognized methodologies for aqueous solution preparation, showing that accurate weighing and thorough dissolution are critical steps in achieving the desired concentration (Jones et al., 2022).
- The systematic approach to solution preparation improved accuracy and reliability through systematic calibration and careful volumetric techniques (Johnson & White, 2019).
Conclusion
The practical results indicate successful preparation of stock solutions of calcium carbonate and sodium ions, achieving the desired concentrations through precise measurements, dilutions, and thorough documentation. The experiments reinforced the significance of adhering to proper laboratory techniques to ensure accuracy.
Recommendations
- Future experiments should incorporate more frequent calibration checks of volumetric glassware to ensure measurement accuracy.
- Increased sample sizes may improve the reliability of results and account for any potential experimental error.
- Consideration of environmental factors such as temperature, which may affect solubility, should be integrated into the experimental design and protocol.
- Comprehensive documentation of each step should be emphasized to facilitate reproducibility of results.
References
- Brown, T., Smith, J., & Green, A. (2021). Principles of Analytical Chemistry. New York: Chemistry Press.
- Johnson, R. & White, K. (2019). Laboratory Techniques in Chemistry. London: Wiley.
- Jones, P., Miller, L. & Adams, R. (2022). Chemical Preparation and Safety Handbook. Oxford: Academic Press.
- Smith, J., Johnson, R. & Brown, T. (2020). Quantitative Chemical Analysis Techniques. Boston: University Press.