I need help with an assignment it is a doc file about a chemistry lab I really need help with the charts. Thank You

Biology Fall 2014 Organic Chemistry Pre-Lab

Name:

Date:

Class:

What is the purpose of this lab?

Hypothesis: Generate your predictions hypothesis based on the introduction that you have read in this lab and check off which organic compound is found in each of your samples.

Sample	Simple sugar	Carbohydrate	Lipid	Protein

Tests: Chemicals are used many times as indicators, that they show us if the presence of specific biomolecules can be found in given substances. This lab focuses on identifying biomolecules using indicators. Read the procedures and complete the indicator table below.

Indicator	Tests for	Original Color/Characteristic	Color/Characteristic it changes to if biomolecule is present

Organic Compound Lab

Introduction

A characteristic of life is molecules containing carbon. These are called organic molecules. In our class we have been referring to them as organic compounds or biomolecules since they are necessary for life. The most common organic compounds found in living organisms are lipids, carbohydrates, proteins, and nucleic acids. Common foods, which often consist of plant materials or substances derived from animals, are combinations of these organic compounds. Simple chemical tests with substances called indicators can be conducted to determine the presence of organic compounds. A color change of an indicator is usually a positive test for the presence of an organic compound.

Purpose

To use indicators to test for the presence of lipids, carbohydrates, and proteins in various foods.

Materials

Indicators (Biuret reagent, Benedict’s solution, Iodine solution)

Foods in beakers, test tubes, test tube holder, hot plate, large beaker, brown paper, well plates

Procedures: see next page

Data Table

Substance	Lipid Test		Carbohydrate Tests			Protein Test
Spot or No Spot	Lipids Present?	Sugar Test		Starch Test	Biuret Color		Proteins Present?
Benedict Color	Sugar Present?	Iodine Color	Starch Present?
Milk
Apple Juice
Oil
Flour
Water

Which test substances contain lipids?

___________________________________________________________________________

Which test substances contain starch?

___________________________________________________________________________

Which test substances contain sugar?

___________________________________________________________________________

Which test substances contain protein?

___________________________________________________________________________

Which substances did not test positive for any organic compound?

___________________________________________________________________________

Biomolecule Lab Procedures

Part I - Testing for Lipids

On the brown paper, draw 5 small squares and label each with the name of one of the foods.
Place one drop of each food in the appropriate square as indicated by the name. Rub the drop of food around on the brown paper.
Set aside paper until dry, about 10 to 15 minutes.
Then hold the paper to the light. Some foods leave a translucent (shiny, wet looking) spot, indicating the presence of lipids.
Write observations (no spot or translucent spot) on the table and place check only for positive test for lipid.

Part II - Testing for Carbohydrates

Starches and simple sugars (saccharides) are two common types of carbohydrates.

Sugar (saccharide) Test

For the sugar test, put 5 mL of each food into a test tube (or ½ test tube).
Add 10 drops of Benedict’s solution to each test tube.

When heated, Benedict’s solution will change color from blue to yellow, orange, or red in the presence of a sugar.

Gently shake each test tube and place in the bot water bath and heat for 3 to 5 minutes. Remove using test tube holder.
In the Data Table, record any color changes and place a check next to any substance that tested positive for sugar.
Wash and dry the test tubes thoroughly.

Starch Test

Place 15 drops of each food in the corresponding numbered wells (1-5) of the well plate.
Add 2 drops of Iodine Solution to each well.

Iodine Solution will change from brown to blue/black in the presence of starch.

Gently shake the well plate. Record any color changes in the Data Table and place a check for positive test for starch.
Wash and dry the well plate thoroughly.

Part III – Testing for Proteins

Place 10 drops of each food in the corresponding numbered wells of the well plate.
Add 10 drops of Biuret reagent to each well.
Gently shake the well plate.

Biuret reagent changes to blue-violet in the presence of protein.

In the Data Table, record any color changes and place a check next to any substance that tests positive for protein.
Wash and dry the well plate thoroughly.

Biomolecules Lab Conclusion

Write-Up Guidelines

First Paragraph: Answer the following question to prepare for your write-up. Turn this information into your introductory paragraph.

Which organic compound (s) did you test for in this lab?
What were the test chemicals (reagents) you used to do the tests?
What food substances did you test?

Body Paragraphs: Write one paragraph for EACH test you did in this lab. Make sure you cover the information in the question below. Be sure to use complete sentences.

What is the name of the test substance and what does it test for?
Describe the organic compound you are testing for.
How do you know from the test that this organic compound is present?
What were the results of the test?
What can you conclude from the results about the presence or absence of this organic compound in each substance?

EXAMPLE:

Here is a good example of how to write one of your paragraphs. It is taken from a lab activity on acids.

Litmus paper can be used to test for the presence of acid. Acids are substances that contain hydrogen ions. They are sour in taste. Strong acids can burn you. Litmus paper turns pink the presence of an acid. When we tested the lemon juice the paper turned light pink; the vinegar turned the paper a darker pink; the buffer solution and the distilled water didn’t change the paper at all. From these results I concluded that lemon juice and vinegar are acids and that the buffer solution and distilled water are not.

Conclusion: Write a paragraph summarizing all of the positive results. Describe anything that might have affected your results. Make a suggestion for improving the lab in the future.