Activity 8: Exploration of Chemistry

Activity 8: Exploration of Chemistry

PhET- Density Activity- Funsheet

Custom Section                                                                                     Name visualizethis39/penaj

Material	Mass (kg)	Volume (L)	Density (kg/L)	Does it Float?
Styrofoam	2.26	15.08	.15kg/L	Yes
Wood	6.03	15.08	.40kg/L	Yes
Ice	13.85	15.08	.92kg/L	Yes
Brick	30.15	15.08	2.00kg/L	No
Aluminum	40.70	15.08	2.70kg/L	No

1.      In the custom setting, choose the ‘My Object’ option in the material drop down box.  Set the mass of your object to 4 kg.  Adjust the volume to find the minimum volume needed to make the object float.

Volume____4.17_____________                Density_____.96kg/L_____________

2.      How does the density of a large piece of aluminum compare to a small piece?
Density remains the same.

Same Mass Section

Material	Mass (kg)	Volume (L)	Density (kg/L)	Does it Float?
Blue	5.00kg	105.00L	47.619	No
Yellow	5.00kg	105.00L	47.619	Yes
Green	5.00kg	102.50L	48.78	No
Red	5.00kg	101.25L	49.382	No

Same Volume Section

Material	Mass (kg)	Volume (L)	Density (kg/L)	Does it Float?
Blue	6.00kg	105.00L	57.14	No
Yellow	8.00kg	105.00L	76.19	No
Green	4.00kg	104.00L	38.406	Yes
Red	2.00kg	102.00L	19.607	Yes

3.  Looking at the data on the previous page, what must be true about the density of

an object in order for it to float?  The object must be under .92kg/L, perhaps higher, but not as high as 2.00kg/L, in order for it to float.

Same Density Section:
4.  Calculate the density of the blue object in this section.
     Mass ___3.00kg__________         Volume____103.00L___________        Density____29.126____________

5.  Explain why both the yellow and red objects float when they have different sizes.  They may be made out of the same materials, such as aluminum.

Mystery Section:

6.  Before you start, pick an object that you think will float.  Styrofoam
 Pick an object that you think will sink.  Brick

Material	Mass (kg)	Volume (L)	Density (kg/L)	Does it Float?
A	65.14	103.38	630.1025	No
B	.64	100.64	6.359	Yes
C	4.08	104.08	39.20	Yes
D	3.10	103.10	30.067	Yes
E	3.53	101.00	34.95	No

7.  In the Custom section describe the difference between how Styrofoam and ice  

 floated.  Also explain why you think this is the case?  The volume remained almost exact.

8.  In the Same Mass Section discuss what was interesting about the blue object’s behavior in the water.  Although the object sank all the way to the bottom it did so slowly.

9.  In the Mystery Section, click on the “Show Table” button.  What is the most dense   

object on the list?  Write its density as well.  Gold; 19.3kg/L

10.  List something you learned from this activity.  Even though some objects can have the same volume or even mass, they may, or may not float, or sink in the same way.

The three 4th grade science education standards that my Teaching Idea meets are: 

1) Science Performance Standard A, Science Connections: A.4.3 When investigating a science-related problem, decide what data can be collected to determine the most useful explanations.

2) Science Standard B, Nature of Science:  B.4.1 Use encyclopedias, source books, texts, computers, teachers, parents, other adults, journals, popular press, and various other sources, to help answer science-related questions and plan investigations.

3) Science Standard E, Earth and Space:  E.4.5 Describe the weather commonly found in Wisconsin in terms of clouds, temperature, humidity, and forms of precipitation, and the changes that occur over time, including seasonal changes.

Green House Effects
How a Fourth Grader Can Help Support a Better Tomorrow

 Goals:  Students will have an introductory look into understanding what green house effects are and be able to identify how harmful gases have an effect on global warming.

Procedures:
1. Click on the following links to view a video of green house effects http://www.youtube.com/watch?feature=player_embedded&v=LFNKfWyGxHw

http://www.youtube.com/watch?v=bSjRM8qNUEQ&feature=player_embedded

2. Draw and list how the sun rays effect the earth and how raidiation is formed.

Questions:
3. Write a hypothesis, or predict then write a possible hypothesis of wthy you think the heat index of summer 2012 in Wisconsinis  so extreme?

4. How do C02 emissions affect the atmosphere?

5. How do scientists meausre C02?

6. Name some ways you can help stomp out the green house effects and educate others by helping the planet in your daily living?

Activity 7: Acids and Bases

Activity 7: Acids and Bases

Water is everywhere! So, lets spend one more activity learning about one of the key aspects of water. Water has the ability to dissociate (break apart from HOH (or H₂O) into H+ ions and OH- ions). We refer to solutions with lots of H+ ions as acids and solutions with lots of OH- ions as bases. By adding chemicals with H+ ions acidic solutions can be made. By adding chemicals with OH- ions basic solutions can be made.

• Teaching Idea “Concept Questions for Chemistry using PhET” posted by Trish Loeblein on the pH Scale simulation at PHET (http://phet.colorado.edu/en/simulation/ph-scale).

1. F, pH levels identify a solution
2. D, pH levels need to be above 7 to be considered a basic solution
3. C, because the solution is more acidic
4. B, due to higher levels of OH-
5. D, three of them have more acidic levels
6. A, more H20 increases the level
7. B, decrease the pH
8. A
9. E
10. A, Since the pH is not 7, then something was added to make the equilibrium shift left. For example, if NaOH was added to water, OH
- is immediately in the solution and some of it will react with the H3O+ , so the pH (which is inversely related to [H3O+ ]), goes up. If something like HCl were added there would be more H3O+ , which would also cause a shift left, but there would be less OH- , (which is directly related to pH), so the pH is less than 7.

• Teaching Idea “Intro to Strong and Weak Acids and Bases” posted by Chris Bires on the Acid-Base Solutions simulation (http://phet.colorado.edu/en/simulation/acid-base-solutions)

Name: Visualizethis39/penaj

Introduction to Strong and Weak Acids and Bases PhET Lab (rvsd 5/2011)

        How does the strength of an acid or base affect conductivity?pH?

Introduction:

When you test your pool’s pH, what are you those little vials or paper strips telling you?  When you hear an acid called “strong” or “weak”, what do those terms refer to?  In aqueous solutions, compounds can exist as molecules (undissociated) or ions (dissociated).  When an acid or a base exists in solution nearly completely as dissociated ions, we refer to that acid or base as strong.  A weak acid or base will donate ions to the solution, but will remain primarily as undissociated molecules.

Notation:

Acids are abbreviated HA, with the H representing the proton (H+) the acid donates to the solution.  The A is referred to as the acidic anion (A-) that is left in solution as the proton is donated.

Strong Bases are abbreviated MOH, with the OH representing the hydroxide ion (OH-) the base donates to the solution.  The M is cation (M+) that is left in solution as the hydroxide is donated. .

Autoionization:

Even without any acid or base added a very small number of water molecules will form protons (H+) and hydroxide ions (OH-).  The protons will then form hydronium ions, the acid ion.

Procedure: PhET Simulations à Play With Sims à Chemistryà Acid-Base Solutions à  

The concentration of the acids and bases used in the  at 0.010 (10^-2) Molar.

·         Begin with a strong acid and lower the pH probe into the beaker.  What is the pH of this solution? 

·         Test this strong acid with both pH paper and the conductivity probe.  What color does the pH indicator become?  Is this strong acid an electrolyte?  Does current travel through this solution?

·         Repeat the above tests with the weak acid, the strong base, and the weak base, and water.  Collect your observations in the table below:

	Strong Acid	Weak Acid	Strong Base	Weak Base	Water
pH meter read (value)
pH paper (color)
Conductivity (bright/dim/none)
Exists as Mostly (ions/molecules)

Procedure:

This simulation allows you to change the concentration of a strong and weak acid and base.

Complete the table below for some strong acids and bases and weak acids and bases by adjusting the concentration.

Strong Acids

Strength	Initial Acid Concentration (mol/L)	[HA] (mol/L)	[A-] (mol/L)	[H+] (mol/L)	pH
	.010 M
	.050 M
	.100 M
	1.00 M

Weak Acids

Strength (approximately)	Initial Acid Concentration (mol/L)	[HA] (mol/L)	[A-] (mol/L)	[H+] (mol/L)	pH
	.015 M
	.150 M
	.015 M
	.150 M

Strong Bases

Strength	Initial Acid Concentration (mol/L)	[MOH] (mol/L)	[M+] (mol/L)	[OH-] (mol/L)	pH
	.010 M
	.050 M
	.100 M
	1.00 M

Weak Bases

Strength (approximately)	Initial Acid Concentration (mol/L)	[B] (mol/L)	[BH+] (mol/L)	[OH-] (mol/L)	pH
	.015 M
	.150 M
	.015 M
	.150 M

Conclusion Questions:

1.      A strong acid is very concentrated / exists primarily as ions. (circle)

2.      A weak base is a nonelectrolyte / weak electrolyte / strong electrolyte.

3.      A strong base is a nonelectrolyte / weak electrolyte / strong electrolyte.

4.      At the same concentration (Molarity) a strong acid will have a higher / lower / the same pH as a weak acid.

5.      As concentration of a weak acid increases, the pH increases / decreases / remains constant.

6.      As concentration of a weak base increases, the pH increases / decreases / remains constant.

7.      As the concentration of a weak acid increases, the number of ions increases / decreases / remains constant.

8.      As the concentration of a weak acid increases, conductivity increases / decreases / remains constant.

9.      As the strength of a weak acid increases, the proportion of ions to molecules increases / decreases.

10.  As the strength of a weak acid increases, the conductivity increases / decreases / remains constant.

11.  What are the pH values of a weak acid with a concentration of 0.10 and a strong acid with a concentration of 0.01, ten times lower?     Weak acid, 0.10 M :____________    Strong Acid, 0.01 M :____________

Explain the significance of the results of your calculation above. ____________________________