- Make a solubility graph for KCl which has:
__22__
- Title
- Axis labels
- units of measurement
- answers based on100mL of water (not 10 mL)
- has one line for averages and one for non-averaged (your group's) data
- The two lines are in colors and are keyed
- Is neat
- Uses available space
- Is on graph paper
- Data points are visible
- Data points are accurate
- Answers to questions (on back of this sheet)
__18__
- Procedure (has all the steps)
__10__
- Lab summary paragraph
__10__
- Introduce the paragraph
- Discuss how reliable you feel your results are
- Discuss possible errors that can occur in the procedure and how to avoid
them (Be sure to give careful consideration to the things in this lab that
would throw off your constants)
- Analyze your graph lines and discuss why they are not the same
5. Lab participation
__5 ___
6. Presentation (neatness, spelling, grammar,
__5____
this list is stapled to front of papers)
QUESTIONS: (Answer these in full sentences. Make sure work is neat and
spell-checked)
- Two compounds were used in this lab. What are their formulas? List the
names of the elements that go into making them.
- What makes a compound different than a mixture?
- How is solubility measured? Is it a property that can be used to help you
identify a substance?
- Was this lab a demonstration of chemical change? Read your book from 75-78
to see if making a solution of KCl and water represents a chemical reaction.
Defend your answer with what you observed in the experiment?
- What are the three main factors that impact the solubility of a solute?
- Why did you have to stir the solution while cooling it? Why did you have
to stir gently?
- KCl is what chemists categorize as a "salt". The container it
comes in says that you should contact a physician if you accidentally ingest
it. Yet, we eat "salt" every day. Why do you suppose KCl is called
a "salt"?
- Explain why the KCl crystals form when the solution is cooled. Incorporate
kinetic molecular theory into your answer.
- Use the graph you made of the averages from the classes to answer these
questions:
A) At 50° C, how much KCl can you dissolve into
100 mL of water?
B) If you had 400 mL of pure water that was boiling, how much KCl would you
be able to dissolve into it?
C) What would you see happen if you stirred 50 g of KCl into a beaker of
100mL of water that was at a temperature of 10° C?
Make sure your answer tells what you'll see before, during and after the
mixing.
10. Compare a "saturated solution" to an
"unsaturated solution".