To find out whether the foods contain starch, fats, proteins and glucose or not.

Apparatus: 

* Test tubes

*Gauze mat

*Test tubes rack

* Dropper

* Beaker

* Bunsen burner

* Spotting tile

* Tripod

Chemicals needed:

*Benedict’s solution

* Biuret solution

* Ethanol

* Iodine solution

Safety:

* Wear the goggle.

* Wear the lab coat.

* Mind the flame.

* Be careful when using the chemicals.

Method:

The iodine test:

1. First we set up the things that the diagram shows.

2. Add iodine solutions to all the substances.

3. See if the colors of the solutions change.

The Benedict’s test:

1. Set up the things that the diagram shows.

2. Add Benedict’s solutions to all the substances.

3. Put all the test tubes into the water bath.

4. Heat the water.

5. See if the color of the solutions changes.

The Biuret test:

1. Set up the things that the diagram shows
2. Add the biuret solution to all the substances.

3. Observe if the color changes from blue to purple/violet or not.

The Emulsion test:

1. Add water and ethanol to the all the substances.

2. See if there id a changes in the solutions.

Result:

In this experiment, we find out that bread and potato contain starches; milk, bread, oil and cheese contain cheeses; egg write, milk, bread, cheese and the unknown solution contain proteins; milk, bread, potato and cheese contain glucose. And we can see that there are a lot of proteins in the egg white by the color of the solution changed from blue to orange. And we know that there are a lot of starches in the bread, too, because the color of the iodine solution changed from brown to black very quickly. When we add the iodine solution to the bread, it changed the color very quickly. It’s almost the same time as the iodine solution touch to the bread.

Conclusion:

Many foods contain a lot of nutrients and they are good for our health. We find out that egg white, milk, bread, unknown solution and cheese contain proteins. These are good for growth, so we have to eat some everyday. And milk, bread, oil and cheese contain fats; and bread and potato contain starches; and milk, bread, potato and cheese contain glucose. All of them can produce energy for our health, so we have to eat some everyday, too.

Starch and Glucose are two types of Carbohydrate. Carbohydrates are food substances, which contain carbon, hydrogen and oxygen atoms in a fixed ratio. The general chemical formula is usually written as Cx (H2O) y. foe example: the chemical formula of glucose is C6H12O6. Fat molecules are made up of carbon, hydrogen and oxygen, too. The hydrogen to oxygen ratio is much larger than two to one. Fat molecules are commonly made up of a glycerol molecule and three fatty acid molecules. At room temperature, some fats are semi- solid. Proteins contain nitrogen. Some proteins also contain sulphur. The basic name of the unit of the protein is amino acids.

Evaluation:

I think this experiment is quite accurate, because it is simple to do, so there will be fewer mistakes. It is easy to understand, too. But I think we have to concentrate more when we are doing the experiment. We have to observe the changes of the experiment very attentively. And I think we have to wash the droppers every time. If we use the dropper to drop Iodine solution first, and then we did not wash it, and continue to use it to drop Benedict’s solution, the color of the solution might not be accurate. So we have to wash the droppers. Also we have to wash the test tubes after testing each type of food, too.

Basic idea of each nutrients