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Dilution Experiment

INTRODUCTION

A dilution is the process of combining measured volumes of a concentrated solution of

analytic with a buffer to make less concentrated solutions. It is a process repeated constantly

in the laboratory. There are several ways to make dilutions. The terms concentrated and dilute

are qualitative terms that refer to a relatively high or low concentration, respectively, of

solute in the solution. Preparing solutions by dilution is convenient. One can make a single

concentrated stock solution of a solute, and then quickly prepare a variety of more dilute

solutions by dilution. Measuring volumes is quicker than weighing. Plus, dilution of a

concentrated solution is a practical method to make solutions that are diluted you would have

trouble weighing the solute. There is a simple equation for calculating dilutions. It is also

easy to present the logic of the equation. We mainly discuss dilution problems using molarity

as the concentration unit.

Objective

1. To study on the biochemistry laboratory and requirements for the course, and theneeded laboratory skills.

2. To practice accuracy and consistency in conducting some experiment that involvesdilution of chemical.

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Methods

1. 9 ml of distilled water are placed in 5 test tubes. The glass/serological pipets used.2.

1 ml of 0.5% (w/v) starch solution blue in the test tube is taken and it was added to the

test tubes that contained 9 ml of distilled water. The solution are mixed and left it to

settle. Labelled as A.

3. 1 ml of test tube A are taken and transferred into the next test tube that contained 9 mlof distilled water. The solution are mixed well and left to settle. Labelled as B.

4. 1 ml of test tube B are taken and transferred into the next test tube that contained 9 mlof distilled water. The solution are mixed well and left to settle. Labelled as C.

5. 1 ml of test tube C are taken and transferred into the next test tube that contained 9 mlof distilled water. The solution are mixed well and left to settle. Labelled as D.

6. 1 ml of test tube D are taken and transferred into the next test tube that contained 9 mlof distilled water. The solution are mixed well and left to settle. Labelled as E.

7. An aliquot of iodine solution are added to all test tubes and the observation arerecorded and described based on the observation.

8. The table below are used to calculate the starch concentration and dilution factor oftest tubes A to E.

Result:

Test Tube Starch concentration () Dilution factor

A 500 10

B 50 100

C 5 1000

D 0.5 10000

E 0.05 100000

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Discussion

The concentration of starch is reducing from that in test tube A until test tube E. This

was shown by the decreasing intensity of the blue-black colour produced in every test tube

after 50L iodine was added from test tube A until test tube E.

In this practical period, the important skills in biochemistry are practiced. These

include the determination of concentration of a chemical mainly by computing the raw data

using formulae in chemistry as well as by measuring the amount directly using right

apparatus, application of unit conversion and proper usage of laboratory apparatus in

conducting an experiment. The technique of determining concentration of a prepared

chemical solution is very important especially when it comes to the usage of a little amount

of chemical with mili- and micro- unit. Other than that, the safety precaution is also practiced.

This is a way to keep the laboratory in a safe condition and keep the experiment out of any

contaminations or interferences.

It is very important to master these skills as a simple mistake during an experiment

can lead to a huge impact and might cause a lot of experimental error which will get the

experiment to failure. Other than that, it can lead to any harm due to exposure to chemical

such as concentrated acid (corrosive), ethidium bromide (carcinogenic), and other harmful

chemical substances which can cause injury or health problems. These do not only occur

during experiments that focused on Biochemistry field alone but also to other branches of

science., studies have reported that 30-40% of medication administration errors are caused by

mistakes in drug calculation (Schulmeister,1999). So, this shows how important it is to

master the laboratory skills especially in applying them in real life.

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Conclusion

It was very helpful if you have the abilities to use the laboratory apparatus or other

biochemistry tool. The smoothness on doing the lab practical is ensured. Measuring volumes

is quicker than weighing. Plus, dilution of a concentrated solution is a practical method to

make solutions that are diluted you would have trouble weighing the solute.

References

Olmsted, J., and G.M. Williams. 1997. Chemistry: The Molecular Science. Wm. C. Brown

Publishers: Boston.

Robyt, John F and Bernard J. White. 1987. Biochemical Techniques Theory and Practice.

H.Robert Horton., K.Gray Scrimgeour.,Laurence A.Moran and Marc D.Perry. Principles of

Biochemistry. Publisher: Pearson.