Serial Vs Parallel Dilution

Serial Dilution Vs Parallel Dilution
Serial Dilution Chemistry

Learning Objective

Calculate the concentration of a diluted solution.

Key Points

Serial Vs Parallel Dilution Method Of Bod Window Awnings Sound Atomic Packing Factor For Bcc And Fcc All Mobile Price In Pakistan 2018 Blog Gilisoft Universal Keygen. Serial Dilutions. Serial dilutions involve diluting a stock or standard solution multiple times in a row. Typically, the dilution factor remains constant for each dilution, resulting in an exponential decrease in concentration. For example, a ten-fold serial dilution could result in the following concentrations: 1 M, 0.1 M, 0.01 M, 0.001 M,. 'You are to prepare two sets of standards by dilution: i) by serial dilution and ii) by parallel dilution. Starting with a primary standard, a 100 times diluted working standard is prepared using a pipette with an accuracy of ±0.1% of the volume it is used to transfer. The volumetric flask has an accuracy of ± 0.1 mL.

Most commonly, a solution’s concentration is expressed in terms of mass percent, mole fraction, molarity, molality, and normality. When calculating dilution factors, it is important that the units of volume and concentration remain consistent.
Dilution calculations can be performed using the formula M₁V₁ = M₂V₂.
A serial dilution is a series of stepwise dilutions, where the dilution factor is held constant at each step.

Terms

dilutiona solution that has had additional solvent, such as water, added to make it less concentrated
serial dilutionstepwise dilution of a substance in solution

The dilutions cover the range from 1/2 to 1/100 unevenly. In fact, the 1/2 vs. 1/3 dilutions differ by only 1.5-fold in concentration, while the 1/10 vs. 1/100 dilutions differ by ten-fold. If you are going to measure results for four dilutions, it is a waste of time and materials to make two of them almost the same. The dilutions cover the range from 1/2 to 1/100 unevenly.In fact, the 1/2 vs. 1/3 dilutions differ by only 1.5-fold in concentration,while the 1/10 vs. 1/100 dilutions differ by ten-fold. If you are going tomeasure results for four dilutions, it is a waste of time and materialsto make two of them almost the same.

Dilution refers to the process of adding additional solvent to a solution to decrease its concentration. This process keeps the amount of solute constant, but increases the total amount of solution, thereby decreasing its final concentration. Dilution can also be achieved by mixing a solution of higher concentration with an identical solution of lesser concentration. Diluting solutions is a necessary process in the laboratory, as stock solutions are often purchased and stored in very concentrated forms. For the solutions to be usable in the lab (for a titration, for instance), they must be accurately diluted to a known, lesser concentration.

The volume of solvent needed to prepare the desired concentration of a new, diluted solution can be calculated mathematically. The relationship is as follows:

[latex]M_1V_1=M_2V_2[/latex]

M₁ denotes the concentration of the original solution, and V1 denotes the volume of the original solution; M₂ represents the concentration of the diluted solution, and V2 represents the final volume of the diluted solution. When calculating dilution factors, it is important that the units for both volume and concentration are the same for both sides of the equation.

Example

175 mL of a 1.6 M aqueous solution of LiCl is diluted with water to a final volume of 1.0 L. What is the final concentration of the diluted solution?
[latex]M_1V_1=M_2V_2[/latex]
(1.6 M)(175 mL) = M₂(1000 mL)
M₂ = 0.28 M

Serial Dilutions

Serial dilutions involve diluting a stock or standard solution multiple times in a row. Typically, the dilution factor remains constant for each dilution, resulting in an exponential decrease in concentration. For example, a ten-fold serial dilution could result in the following concentrations: 1 M, 0.1 M, 0.01 M, 0.001 M, and so on. As is evidenced in this example, the concentration is reduced by a factor of ten in each step. Serial dilutions are used to accurately create extremely diluted solutions, as well as solutions for experiments that require a concentration curve with an exponential or logarithmic scale. Serial dilutions are widely used in experimental sciences, including biochemistry, pharmacology, microbiology, and physics.

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BIOL 1406

PreLab 2.5

When do I use the serial dilution technique instead of the parallel dilution technique?

Another way to make dilutions is to use some of your existing stock solution to make a dilute solution, then use some of the dilute solution to make an even more dilute solution, then use some of that solution to make an even more dilute solution, and so on. This procedure is called the serial dilution technique.

There are two situations where serial dilutions should be used rather than parallel dilutions:

FIRST: Use a serial dilution when you need several solutions of the same solute and there is a constant dilution factor. For example, suppose you have a 2 M stock solution of KMnO₄ and you want to make 15 mL of each of the following concentrations of KMnO₄: 0.2 M, 20 mM, 2 mM, and 0.2 mM. Notice that the concentration of each solution is 1/10^th the concentration of the previous solution in the series. The factor by which each solution is diluted compared to the previous one is called the dilution factor.

To calculate the dilution factor for each dilution, divide the concentration of the starting solution by the concentration of the diluted solution. For example, for the first dilution 2 M divided by 0.2 M equals 10. For the second dilution, 0.2 M divided by 20 mM equals 10. For the third dilution, 20 mM divided by
2 mM equals 10. And for the fourth dilution 2 mM divided by 0.2 mM equals 10. Therefore, this series has a constant dilution factor of 10.

SECOND:Also use a serial dilution when the dilution factor is so large that the amount of stock solution needed to make the dilution in one step (using the formula C₁V₁ = C

₂V

Serial Dilution Vs Parallel Dilution

₂) is too small to measure accurately. Remember that the smallest volume you can measure with the micropipettors is 2 μL.

YOUR TURN
You have a stock solution of 1.6 M sucrose and you need to prepare solutions with the following concentrations of sucrose: 0.4 M, 0.1 M, 25mM, and 6.25 mM.What is the dilution factor for this series?	Hint	Check your answer.
You plan to prepare 4 solutions by serial dilution. The concentration of your stock solution is 2.7 M and the dilution factor is 3. What will be the molarity of your four solutions?	Hint	Check your answer.
You have a 1.0 M stock solution of glycine (an amino acid), and you need 5 mL of a 0.1 mM solution. By what factor do you need to dilute your stock solution?	Hint	Check your answer.
Using the formula C₁V₁ = C₂V₂, calculate the amount of stock solution you need to make 5 mL of a 0.1 mM solution from a 1.0 M stock solution. Express your answer in mL:	Hint	Check your answer.
Do you have a measuring device that will accurately measure this amount? YES NO	Hint	Check your answer.
Explain.	Hint	Check your answer.

YOUR TURN
For each of the following situations, state whether the parallel or serial dilution technique would be more appropriate, and explain your reasoning.
You need 20 mL of a 5 mM glycerol solution. You have a 1.0 M glycerol stock solution on hand. Which dilution technique is appropriate and why?	Hint	Check your answer.
You have a 2.5 M stock solution of EDTA. You need 50 mL each of 2 M, 0.5 M, 0.2 M and 0.1 M solutions of EDTA. Which dilution technique is appropriate and why?	Hint	Check your answer.
You have a 2.0 M stock solution of sucrose. You need 100 mL each of 1 M, 0.5 M, 0.25 M, 0.125 M, and 62.5 mM sucrose solutions. Which dilution technique is appropriate and why?	Hint	Check your answer.

Serial Dilution Chemistry

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