Biology

Lab Report: Scientific Method Your Name: __________________________________________________________________

Purpose of this Lab What is the goal of this lab? What question is it trying to answer, or what problem is it trying to explain?

Hypothesis After reading the lab instructions – but before starting the lab – record your best “educated guess” about what will happen in the experiment. What hypothesis can you generate about the effect of adding salt to water?

Experimental Design List the materials used in this lab, and the procedure you followed.

Materials: 1.

2.

3.

Procedure (list steps in the order in which you performed them): 1.

2.

3.

Data Record the data you collected in the lab. (The data table and the graph.)

Table 2. Boiling point temperatures of various salt solutions.

Beaker/Concentration of NaCl (M)

Boiling Point Temperature (°C)

Pure tap water

1 tablespoon salt solution

2 tablespoon salt solution

3 tablespoon salt solution

Graph the data from Table 2 Label each axis (X and Y will NOT do). Devise a scale for each axis and label that scale (1, 2, 3…) Plot the data points. Connect the data points by drawing a straight line. Title the graph.

Analysis Analyze the data you collected in the lab. How does the data presented above relate to the hypotheses you generated earlier in lab? Are any hypotheses disproved by your experiment? Use your graph to determine the boiling point of a solution made with 2 ½ tablespoons. This use of a graph has generated a hypothesis that a 2 ½ tablespoon solution boils at ____degrees C. Prepare a 2.5 M solution and verify your hypothesis.

Conclusion After conducting the experiment, how would you now explain the problem(s) or answer the question(s) raised when you described the purpose of the lab? Be sure to base your answer on the data you collected. If you are given a solution of unknown concentration, can you determine its concentration? Explain.

Additional questions for this lab:

Notebook Activity: How do you apply the scientific method in everyday life? List examples.

Notebook Activity: Conversions between units If there are 1000 meters in a kilometer, how many meters are there in 0.05 km? _____ If there are 1,000,000 micrometers (µm) in a meter, how many µm are there in one millimeter (mm)? _____ If an object is 334 µm wide, how many mm wide is it? ____ If we have one Liter of a solution, how many milliliters (ml) is that? ____

Did your TAP water boil at 100 degrees C? If not, what might account for this? ____

An experimental control is a test that lacks the experimental variable. Was one of the solutions prepared in this lab a control? If so, which one? ____ In our experiment, you controlled one of the factors. Which one (temperature or NaCl concentration) was it? ___ This factor was the independent variable; it was controlled by you, the experimenter. The other variable was a consequence of changes you made. This is the dependent variable. It was a consequence of changes in the independent variable. What factor (temperature or NaCl concentration) was the dependent variable? _____

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