Chapter 2 Mass Changes in Closed Systems

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

Exp. 2.1 The Mass of Dissolved Salt

Data and Observations
-individual data
        -class data table w/ mass before, mass after and mass change and UNITS.     
Conclusion  (Complete the circle of Science!)
       - respond to the purpose based on the data collected- "When salt dissolves in water...."

Discussion (number, respond, skip a space between each response)

1. What is the mode (the value that appears the most often) for the change in mass?

2. In the class data, circle the initial masses associated with the mass changes that were zero or close to zero. 
    Did all students begin with the same initial masses? 

3. 
Does the initial mass affect the mass change? Explain, and include data as evidence in your explanation.

4. Explain the difference between the results of Exp. 2.1 and those from Fig. 1.13 on p.14 in the textbook. 


Sources of Error
 
1. How would water leaking out of the vial during mixing affect the change in mass calculated?

2. Describe another error in the procedure that could have resulted in a loss of mass. 



Exp. 2.6 The Mass of a Gas

Data and Observations:
- Qualitative data
- Quantitative class data table 
- Histogram the CHANGE  in mass. (hand drawn of class data)
     

Conclusion Statement - Respond to the purposes based on the class data collected.

Discussion
1. Describe the class data that led to your conclusion statement.
   (i.e.The histogram of the change in mass when_____ shows a strong central tendency centered around ______ g.)

2. Describe whether or not a new substance was produced during the reaction, and describe qualitative evidence to support your idea.

3. Describe why even though new substances were produced, the mass did not change. (Clue: Chapter 2 title.)

4. Does a gas have mass? What is your evidence? Describe quantitative data.

Sources of Error
1. Describe 1 specific procedureal step from this exp. that could have introduced error into your experiment.

2. Indicate the effect on the results that this error would have had.




Exp. 2.5 The Mass of Copper (Cu) and Sulfur (S)

Data and Observations
- Qualitative data table
- Quantitative: your data and class data table
- Histogram of class data by hand.

Conclusion - Respond to the purpose based on the class data collected.

Discussion
1. Describe the class data that led to the conclusion statement.
   (i.e.The histogram of the change in mass when _____ shows a strong central tendency centered around ___ g.)

2. The substance or matter produced by heating a mixture copper and sulfur together is a new substance that was not
    present before heating of the mixture. Describe two qualitative observations that support this conclusion.

3. Explain why, even though new substances were produced, the mass did not change. Think about the procedure or
    design of this experiment.

4. Circle the two smallest and the two largest initial masses in the class data table. Does the initial mass affect
    the
change in mass?  Describe data as evidence to support your response.
  

Sources of Error
1. Describe one specific procedureal step unique to this experiment that could have introduced error into your results.
 
2. Describe the effect that this error would have had on the change of mass. (Do not just write- "...inaccurate...")


Exp. 2.4 The Mass of Ice and Water
Data and Observations:
        - Your own data
.
- Class data table
- Histogram


Conclusion - Respond to the purpose based on the data collected: "When ice melts..."

Discussion

1. What is the value of the strong central tendency of the histogram that led to your conclusion statement?
   
   -(i.e.The histogram of the change in mass when ___ shows a strong central tendency centered around ______ g.)

2. In the class data, circle the initial masses associated with the mass changes that were zero or close to zero.
    Did all students begin with the same initial masses?


3. Does the initial mass affect the mass change? Explain, and include data as evidence in your explanation.
   
4. What happens to the VOLUME of water when ice melts? From the results of THIS experiment, what happens to the MASS of the water when ice melts into a liquid?

Sources of Error

        1. If one group accidentally used two spoonfuls of ice, would this have affected their mass change? Explain.

        2. If the condensation that formed on the outside of the vial during the experiment was not wiped off, how would the
            results have been affected? Explain.
 



       




Exp. 2.5 The Mass of Copper and Sulfur

Data and Observations
- Qualitative data table
- Quantitative: your data and class data table
- Histogram of class data by hand.

Conclusion - Respond to the purpose based on the class data collected.

Discussion
1. Describe the class data that led to the conclusion statement.
   (i.e.The histogram of the change in mass when _____ shows a strong central tendency centered around ___ g.)

2. The substance or matter produced by heating a mixture copper and sulfur together is a new substance that was not
    present before heating of the mixture. Describe two qualitative observations that support this conclusion.

3. Explain why, even though new substances were produced, the mass did not change. Think about the procedure or
    design of this experiment.

4. Circle that two smallest and the two largest initial masses in the class data table. Does the initial mass affect
    the
change in mass?  Describe data as evidence to support your response.
  

Sources of Error
1. Describe one specific procedureal step unique to this experiment that could have introduced error into your results.
 
2. Describe the effect that this error would have had on the change of mass. (Do not just write- "...inaccurate...")



Exp. 2.6 The Mass of a Gas

Data and Observations:
- Qualitative data
- Quantitative class data table 
- Histogram the CHANGE  in mass. (hand drawn of class data)
     

Conclusion Statement - Respond to the purposes based on the class data collected.

Discussion
1. Describe the class data that led to your conclusion statement.
   (i.e.The histogram of the change in mass when.....shows a strong central tendency centered around ______ g.)

2. Describe why even though new substances were produced the mass did not change. (Clue: Chapter 2 title.)

3. Describe whether or not a new substance was produced during the reaction and provide qualitative evidence. 

4. Does a gas have mass? What is your evidence? Describe quantitative data.

Sources of Error
1. Describe 1 specific procedureal step from this exp. that could have introduced error into your experiment.

2. Indicate the effect on the results that this error would have had.














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