HW #11 for 3/26

1) HW #11-pg. 589 #7, 9-10
2) All late HW due Thurs 3/26
3) Test on Thursday-study guide up
4) Composition books due—8 take home labs; 4 in class labs: mixture stations, kool aid, salt/boiling, polluted water
5) Science-Math family night on Apr 17th  from 5-7pm (not positive date)

Study Guide for Chapter 15 & 16 Test

Chapter 15

• Know what a solution is
• Be able to explain difference between solvent and solute
• Know what a homogeneous and heterogenous mixtures are
• Know what an aqueous solution is and what is in it
• Explain that polar dissolves with polar and what does not dissolve with polar
• Know whether water is polar or nonpolar
• Know what it means for a solute dissolve in a solution
• Know difference between saturated, unsaturated, supersaturated
• Know difference between concentrated and dilute
• Know the three factors that affect how solutes dissolve and explain how it affects it to make it dissolve faster
• Know the differences in the formulas for: mass percentage, molarity and dilution. Be able to read a question and know what formula applies in that case.
•  Know what molarity represents in a solution. Understand difference between high molarity and low.
• Explain how to dilute a solution you need to add water and be able to calculate how much water needs to be added.
• Be able to explain the affect of salt on water's freezing and boiling point

 pg. 559 Answers
#2=C   #3=D   #4=C   #5=B  #6=A  #7=D   #11--written answer

Chapter 16

• Know definition of acid and base
• Be able to explain why H+ is a proton
• Know that each acid has a conjugate base and how to determine its formula
• Know that each base has a conjugate acid and how to determine its formula
• Understand that to make a conjugate base you take away a H+, but to make a conjugate acid you add a H+
• Understand how a strong acid differs from a weak acid

pg. 593 Answers
#1=B   #2=C   #9=weak acid   #10=strong acid

Dilution of polluted water lab

Dilution of Polluted Water Lab

Purpose: All human activity and many natural processes produce pollution. Pollution is a generic term for contamination from any activity that has a negative impact on the environment or human health. Pollution can travel by three major pathways: air, water, and land. Since it can travel using several different methods, it can be very difficult to remove pollution completely once an area has been contaminated. Sometimes even very small amounts of pollution can have a negative effect on people, animals and plants, so detecting and removing it can be complicated and expensive. In this activity, we will take a sample of a chemical and treat it as if it is ‘polluted water’. We will then dilute the sample five times, decreasing its concentration by ten times for each step, all the way down to one-hundred thousandth of the original concentration. Finally, we’ll test each sample with a drop of chemical indicator to attempt to detect ‘pollution’ at each concentration.

Directions:

1. You should have six test tubes in a test tube rack.

2. Obtain the solution representing the “polluted water” and place 10 mL of the “water” in a graduated cylinder.

3. Pour the 10mL of “polluted water” in your first test tube on left. Rinse out graduated cylinder thoroughly.

4. Using a plastic pipette, remove “polluted water” from test tube #1 and measure 1 mL in your graduated cylinder.

5. Transfer this 1 mL to test tube #2 and rinse out your graduated cylinder.

6. Using graduated cylinder measure 9mL of “clean water” and add to test tube #2. This dilutes the polluted sample to ten times less concentrated.

7. Then take repeat the steps and measure 1mL of “polluted water” from test tube #2 and add to test tube #3. Rinse out graduated cylinder.

8. Add 9mL of clean water to test tube #3.

9. Repeat these steps until you are at test tube #6.

10. After you have your “polluted water” samples in test tube #1 through #6, take 1 drop with your pipette and test on pH paper. Record the color and pH number.

11. Then add 1 drop of indicator to each of the test tubes and record the color of each. You may swirl the test tube to mix the indicator.

Data Table:

	Test tube #1	Test tube #2	Test tube #3	Test tube #4	Test tube #5	Test tube #6
pH paper color
pH numerical value
Color with indicator

Analyze:

1. What trend did you notice in the colors of the test tubes after the indicator was added and the test tubes became less concentrated and more dilute? Why do you think this happened?

2. What happened to the pH value from test tube #1 to #6? What is happening to the solutions? Did it ever become “neutral”?

3. Do you think that you can remove pollution from water by simply diluting it? Explain why or why not using your evidence.

Changing the boiling point of water lab

Changing the Boiling Point of Water

Purpose

To determine how adding a solute to water will affect the boiling point of water.

Calculations:

1. Calculate the molar mass of NaCl.

2. Determine the amount of salt needed in grams to make a 0 M solution of salt that has a volume of 200 mL.

3. Determine the amount of salt needed in grams to make a 0.5 M solution of salt that has a volume of 200 mL.

4. Determine the amount of salt needed in grams to make a 1.0 M solution of salt that has a volume of 200 mL.

5. Determine the amount of salt needed in grams to make a 1.5 M solution of salt that has a volume of 200 mL.

6. Determine the amount of salt needed in grams to make a 2.0 M solution of salt that has a volume of 200 mL.

Results: record the temperature that the water boiled at in Celsius.

Sample	0 M	0.5 M	1.0 M	1.5 M	2.0 M
Trial 1
Trial 2
Trial 3
Average

Concentration	Average BP (°C)	Change in BP from 100 °C (°C)
0.0 M	99.5 C	-.5 C
0.5 M
1.0 M
1.5 M
2.00 M

Analysis

1.  Graph your data using the average boiling temperature (molarity on x-axis and temperature on y-axis) and see if there is a line of best fit for the data. 

2.  What occurs when you add salt to water? What is it causing to the water’s properties?

What is the solvent, solute in the solution? Explain why it is a