Introduction Worksheet


The standard lab report will typically have 8 sections:

 

1. Title

2. Abstract

3. Introduction - link to a pdf form for the Introduction

4. Experimental

5. Results

6. Discussion

7. Conclusion

8. References

 


Section I. General Idea of the Introduction

 

The introduction section is where the chemist provides a context for the experimental work performed.  Providing a context entails:

 

1) Describing the specific goal of the lab

            What are you trying to figure out?

 

2) Stating what scientific information already exists on the subject of this lab. 

            What theories and equations are employed in your lab?

 

3) Describing how your specific lab goal from point #1 relates to the scientific theories described in point #2.

            How does your experiment illustrate or use the theory?

 

Tips:

Do:

1)    Keep it brief, 1 – 2 paragraphs.

2)    Read from as many sources as possible to understand the context of your experiment.

3)    Cite any source you use.

4)    Use your own words or examples to illustrate theories.

 

Do not:

1)    Do not copy the introduction from your lab textbook or anywhere else.

2)    Do not use “I” or “we” if at all possible.

3)    Do not include results and/or conclusions.  These go in the Results and Conclusions sections, and also might be briefly listed in the Abstract.



Section II. Step by step example of writing an introduction.

This example is based on Experiment #3, “Estimating the Weight Percentage Sugar in Soft Drinks”.  

 

STEP 1: Answer the following questions.

 

Question 1:

What is the specific goal of the lab? What are you trying to figure out?

 

Answer 1:

The goal of this laboratory investigation is to use the relationship between density and percent sugar to determine the percent sugar in a soft drink.

 

Question 2:

What scientific information already exists on the subject of this lab? What theories and equations were employed in your lab?  In the case of lab #3, you could rephrase this question as, “What scientific information already exists about density of solutions and the relationship between a solution’s density and the percentage of its components?” 

      –Remember to cite the sources you use with number in square brackets, which will refer to the corresponding source at the end of the Introduction.  (In a complete lab report, the sources would be located at the very end in the References section.)  See the example with [1] below.

            Rule of thumb: If looked something up in a book, you should cite that book.

 

Answer 2:

Density is the relationship between the mass of an object and its volume.  The more dense an object is, the greater its mass per unit volume.  The density of a solution is determined by the density of its individual components and their relative amounts.  For a solution composed of solvent and one solute, the relationship between the solution’s density and the relative volumes of solute and solvent is summarized by Equation 1 [1]:

:Equation-1.jpgEquation 1

 

Question 3:

How does your experiment illustrate or use the theory?

 

Answer 3:

Flat soda can be considered a solution where the sugar is the solute and the water/flavoring is the solvent.  With these assumptions, the relationship between the soda’s density and the percent sugar (Equation 1) can be used to construct a calibration curve assuming that the density of sugar is 1.5805g/ml and the density of water/flavoring is 1.002g/ml [1, 2].  By comparing the predicted density from the calibration curve to the actual density measured from flat soda, the percentage sugar of flat soda can be determined. 

 


STEP 2: Now that you have answered each of the three questions, combine your answers to questions 1, 2, and 3 in paragraph form.

 

The Introduction:

The goal of this laboratory investigation is to use the relationship between density and percent sugar to determine the percent sugar in a soft drink.

Density is the relationship between the mass of an object and its volume.  The more dense an object is, the greater its mass per unit volume.  The density of a solution is determined by the density of its individual components and their relative amounts.  For a solution composed of solvent and one solute, the relationship between the solution’s density and the relative volumes of solute and solvent is summarized by Equation 1:

:Equation-1.jpgEquation 1

 

Flat soda can be considered a solution where the sugar is the solute and the water/flavoring is the solvent.  Then, the relationship between the soda’s density and the percent sugar (Equation 1) can be used to construct a calibration curve assuming that the density of sugar is 1.5805g/ml and the density of water/flavoring is 1.002g/ml [1, 2].  By comparing the predicted density from the calibration curve to the actual density measured from flat soda, the percentage sugar of flat soda can be determined.  

 

 


STEP 3: Don't forget to include your references with appropriate numbers that correspond to your citations.

 

 References:

 [1] Brown, P., General Chemistry II Laboratory Experiments, McGraw Hill, NY, 2000.

[2] Palmer, W.G., Experimental Physical Chemistry (Volume 0), 2nd ed., Cambridge University Press, Cambridge, 2009.

 


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