Preparation of Solutions
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Introduction
Preparation of Solutions- 10/27/09 Introduction: The purpose of this laboratory experiment was for the student to advance in ability to prepare solutions of target concentration, use of analytical balances, and use of laboratory glassware. Goggles and other safety precautions must be observed throughout. To prepare a solution of target concentration based on molar concentration of mass percent involves the formulas for such units. Molar concentration, or molarity (M), is the number of moles in exactly one liter of solution. This is used because chemists want information about the number of reacting particles in a reaction and is often used as a conversion factor. Mass percent (m/m) of a solution is calculated by dividing the mass of the solute by the mass of the entire solution and multiplying it by 100. Scientists use this information to prepare solutions. An example of an application of this information would be in a hospital setting. Intravenous fluids going into a patients body must be a specific concentration so it does not overly disturb the balances withheld by the many semi permeable membranes of the body. ...read more.
Middle
A special piece of laboratory equipment called a spectrophotometer is used to calculate the absorbance of the solution once prepared. This is to compare the molarity of the solution to the target molarity to assure accuracy. Procedure One: Procedure one used the instructions outlined in the laboratory experiments manual for this course. A plastic weigh boat was tared and the required mass of copper sulfate pentahydrate (CuSO4 ? 5H2O) was added to the boat on top of the analytical balance. The small amount was transferred to a beaker and dissolved in a minimal amount of deionized water, no more than six milliliters was used. This solution was then transferred to a ten milliliter flask and combined with enough deionized water to make a ten milliliter solution and gently mixed together. Some of the solution was moved to a cuvette and the instructor verified the correctness of the prepared solution using the spectrophotometer. Upon being verified by the instructor, a new target concentration was assigned and prepared using the same method. ...read more.
Conclusion
5H2O): Cu- 63.55 + SO4- (32.07)+ (16 x 4=64) + 5H2 - (1.008 x 10=10.08) + 5O- (16 x 5=80) = 249.5 g/mol Mass of (CuSO4 ? 5H2O) required to prepare 10.00 mL of a 0.140 M solution: Mass (CuSO4 ? 5H2O) = molar mass (CuSO4 ? 5H2O) x molarity solution x volume to be made x (1L/1000mL) .349468(.3)=249.6 g/mol x 0.140 M x 10.00 mL x (1L/1000 mL) Procedure Two: Volume of a 0.200 M stock solution required to make each solution: Molarity of solution x Volume to be made =Volume stock required 0.200 M .06 (absorbance .65) x 10 mL = 3 mL .200 M Conclusion: This experiment provided further understanding about the concentration, preparation, and dilution of solutions. Calculations were confirmed by experimental data obtained from quantitative and qualitative observations. Pre-Lab: Calculate the volume of 0.200 M stock solution required to make each solution as follows: Molarity of target Volume to be made Volume of 0.200 M stock required .030 10mL 1.5 .050 10mL 2.5 .060 10mL 3 .080 10mL 4 .100 10mL 5 .120 10mL 6 ?? ?? ?? ?? CHEM 1151L Survey of Chemistry One Lab Section 206 Preparation of Solutions- 10/27/09 ...read more.
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