Chapter 3 Characteristic Properties

Reminders:
1. Use complete sentences for every question with proper punctuation.
2. No pronouns.
3. Use part of the question in your responses.
    Do not begin with "It..." ,"No, because..." "Yes, because..."   
4. Describe data as evidence to support your response.
5. Be specific with sources of error.

Scroll down to see experiments.



Exp. 3.7 The Density of a Gas

Data and Observations
- Individual data table
- Class data table
- Sample histogram of class data

Conclusion statement
        -respond to the purpose based on the data collected.

Discussion   (skip spaces between your responses)

        1.
Describe the class data (i.e. the strong central tendency of the histogram) that led to the conclusion statement.
   
        -(i.e.The histogram of the density of the.....shows a strong central tendency... ______ g/cm3.)

        2. Based on the histogram what gas could have been produced. Evidence? Be resourceful.

        3.Explain if the density of the gas is or is not dependent on the amount of gas? Look at this  sample data.

        4. How do the densities of gases compare with that of liquids and solids? Be resourceful and provide data to
            support your ideas.

Sources of Error
        1. How would the volume of the gas collected be affected if a large air bubble was in the bottle before the gas from the                 Alka Seltzer was collected?

        2. How would this large air bubble affect the calculated density of the gas collected? Explain by describing the equation
            for density in your response.


Exp. 3.9 Freezing and Melting
 
Data and Observations
1. Qualitative observations (could be listed alongside table of time and temperature)
2. Line graph time (on x axis) vs. temp. (on y axis)
3. Class histogram
Conclusion
       - respond to the purpose based on the data collected.
Discussion
      1.
Define freezing point.
      2. Examine the histogram (linked above) of past years data. How many strong central tendencies are there and what are the temperature values for the strong central tendencies?
      3. Is freezing point a characteristic property of a substance? Provide two reasons to support your response.
Think about your response to question number two. Remember that every lab station had different amounts of the substances.            
      4. If experiment 3.9 was repeated using water instead of the substances, at what temperature would a plateau be seen? Sketch a graph illustrating the freezing temperature of water. You do not need to draw complete scales for either axes.

Sources of Error
       1. Why did the substance need to be stirred as it cooled? (Check in textbook.) How would the cooling of the substance be affected if it were not stirred consistently? Think about where cooling occurs first.
       2.
If one group were accidentally given a mixture of the two substances, how do you think the data collected would be affected? What do you think the graph would look like? (Think about this one.)
         

Exp. 3.11 Boiling Point
      

Data and Observations
- Indicate whether 10 or 20 ml of liquid was used.
- Line graph- properly labeled
- class histogram

Conclusion statement
       - Simply respond to the purpose based on the data collected.

Discussion (Use complete sentences. Do not use abbreviations. Skip a space between each response.)

      
1. Define boiling point.

       2.
Examine the histogram (link above) of past years data. How many strong central tendencies are there and what are the temperature values for the strong central tendencies?

       3.
Describe two reasons why boiling point is considered to be a characteristic property of a substance?  Describe data from the experiment as EVIDENCE to support your idea.
    
       4.. If one pair of students was given 10 ml of liquid and another pair was given 20 ml of the same liquid, how would their graphs be different? How would their graphs be the same?  You may either describe or sketch neatly your response to this question.

Sources of Error
       1. What might the graph of the temperature as a function of time look like if the the flame was on too high and the test tube with the liquid to be heated was too close to the wire stand?

       2. What would the graph had looked like if the heat from the flame was very inconsistent?



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