Lab 5.1 Rates of Reaction

Ok so the last experiment that we did really focused in on the reasons that a reaction will proceed at a certain rate. The way that you will need to think about this process has to do with particle collisions and how they influence how fast the reaction will happen. For a reaction to happen we need what is called an effective collision. This means that the particles have collided in such a way that there will be a chemical reaction. The changes we made in the lab, influence the number of effective collisions that were occuring.

The first thing that we did in the lab was try to make a plan so that you could determine how the lab would be done so that you could tell how changing each variable would influence what happened. Describe quickly what you did in the experiment. Include in this description why it was important that you controlled the variables in a certain manner. In the lab pre-assessment that you did we chose that student B was the one that had the best procedure to determine how a variable affected the rate. Why was his method the best? What would happen if you varied multiple variables at the the same time?

By changing the concentration of the vinegar, the temperature of the vinegar, and the amount that the tablet was crushed the rate of reaction was changed. Describe, using particle collisions why each variable changed the rate. Also describe if the results in your experiment were consistent with what you expected to happen. If they aren't, describe something that could have gone wrong in the process.

Enrichment: Do some online research and find an example of a real-life catalyst. Find out what changes in the reaction and how that has a significant influence on the rate of reaction. If you need help getting started catalysts are often used in industrial processes in order to make reactions more efficient. Also, you could look at enzymes and see specifically how they change a biological process.

Lab 4-2 Heating and Cooling Curves

Now that you have had the chance to digest the heating and cooling curve process a little bit, I am going to ask you guys to think about what happened in the process.

Paragraph #1: Write a clear procedure for what you did in this experiment. This may be in bullet and complete sentence form, or paragraph form. The blogs have been getting better, but the complete sentence issue is a must.

Paragraph #2: Take a look at the graph that you made as a result of the data that you collected. Identify the melting point of lauric acid from your graph. Identify the freezing point from the second graph that you made [many of you put the on the same axis, which is fine]. Are these two values the same (and should they be the same)? Explain how you determined the freezing and melting points from your data.

Paragraph #3: As you heat a substance to its melting point and through the phase change there are changes that occur in both kinetic and potential energy. Explain what kinetic energy is and when it is increasing during your heating curve and decreasing in your cooling curve. Explain what potential energy is, and also explain when it is increasing and decreasing in your curves.

Enrichment:

Lauric acid of course has an actual melting point. Find the actual melting point and compare it to your data. Calculate the percent error and predict a reason why you were high or low (the thermometers are accurate, so don't blame them.)

Find out more about lauric acid. Maybe what it is used for, or could potentially be used for, find its chemical formula, structure, anything relevant about the chemical. Reference the source that you used to find the information.

Blog 4.1 Having Fun With Air Pressure

Answer each of the following AND Explain!!! 

I am looking for you understanding of how and why the particles in the gases cause the change that you are predicting.

You will not receive full credit if you do not explain with complete sentences.

 

1. A decrease in pressure causes the volume of a balloon to _______________________.

                                                                                                  (increase, decrease or stay the same?)

2. Adding more gas to a bottle ____________________ the pressure in that bottle.

                                                       (increases or decreases?)

3. As the volume of a cylinder is increased the pressure will __________________________.

                                                                                                    (increase, decrease or stay the same?)

4. Increasing the pressure in a tire by adding more gas will cause the volume to _______________ .

                                                           (increase, decrease or stay the same?)

5. As the temperature of a closed container of water is increased the amount of water vapor  above the water causes a(n) _________________________ in vapor pressure.

                                          (increase, decrease or no change?)

6. As the air pressure above a liquid is increased by adding more air, the boiling point of the liquid will _____________________.  (increase, decrease, or remain the same?)

7. If a balloon filled with air is taken under water to a depth of 10 feet, it’s volume will ______________________ . (increase, decrease, or remain the same?)

8. The temperature of a beaker of boiling water will __________________ as more heat is  added.                                                                                  (increase, decrease, or remain the same?)

  

9. Hot air rises because it is _____________ dense the cold air around it.  

                                                  (less or more?)

10.  When heated, the volume occupied by air in a balloon  will ___________________________ .

                       (increase, decrease or stay the same?)

ENRICHMENT: 

Try to explain what happened to the tanker car shown in the pix, in terms of gas particle behavior.  The situation happened when some workers cleaned the tanker out with a hot water flush and then sealed the tanker car lid after doing their work in the middle of the day.  That night, the air temperature dropped down to the 35⁰F range.  The car did this sometime during the night.

Properties of Ionic and Covalent Compounds (3.1)

Conclusion:

 Respond to each item asked for on the rubric and answer the following questions.

1. List the general properties of ionic compounds. (hardness? conductivity? conductivity in solution? melting point?)

 

2. List the general properties of covalent substances. (hardness? conductivity? conductivity in solution? melting point?)

 

3. What types of elements combine to form ionic bonds? Explain what happens with electrons with this type of bonding.

 

4. What types of elements combine to form covalent bonds? Explain what happens with electrons with this type of bonding.

5. Why do covalent compounds lack the ability to conduct electricity as a solid or in solution?

 

6. Why do ionic substances conduct electricity in solution, but not as solids?

Enrichment:

Solutions containing ions are often called “electrolyte solutions.”  Research electrolytes and find out:

¨  Why drinks like Gatorade advertise that they contain electrolytes,

¨  What electrolytes have to do with you and exercising,

¨  How electrolytes are used by your body to transmit messages from your brain to your muscles,

¨  What is the electrolyte substance used by your body?

Post 2.2 - Bag of Ions and Periodic Table Chem Crunch

After completing these activities I am looking for you guys to communicate your understanding for the organization for the periodic table. So please consider the following [Bill Nye Reference]

In your own words describe how the periodic table is arranged, you may wish to include something about the groups and periods, electron configuration, valence electrons, and the different families.

For the second part, I want you to compare and contrast ions and atoms:

• What is similar about atoms and ions of the same element
• What is different about atoms and ions of the same element
• Why do ions form?
• How can you predict the charge on an ion by looking at valence electrons and location on the periodic table

Overall, I am looking for how well you understand these concepts, if you have any questions use your packets and notes and chem crunches, and don't be afraid to ask questions!!

Lab 2.1 Grouping of Elements

1.    Based on the information in your text on p158-160 (or another source that names the different groupings on the periodic table),  “Name” the groupings of elements that you created on the last page.

2.  Classify the four properties tested in this lab as either a physical property or chemical property.  Explain your thinking.

3.   a)  State what is unique about elements that are “metalloids.” 

b)  Identify any elements among our seven that are metalloids.

c)  List the names and symbols of all the metalloids. 

4.   When you look at a Periodic Table, you will notice that the seven elements we tested are all clustered near each other. 

State the trend that appears to exist:

a)  In terms of metallic character of elements, as you proceed from elements on the left to elements on the right in the Periodic Table.

b)  In terms of metallic character of elements, as you proceed from elements near the top to elements near the bottom in the Periodic Table.

ENRICHMENT:  Some elements, like lead (Pb), have symbols that due not seem to match their names.  Pb is derived from the Latin name for lead, which is “plumbum.”  This is due to the fact that this element was used in Roman times for making pipes for drinking water (“plumb”ing pipes).  There are 10 other elements like this.  Find one or more of them, and research why the symbol is what it is.

Lab 1-4 Physical and Chemical Changes

We have talked a bunch about physical and chemical changes now. What I would like you to do is to design a clear set of criteria that you can use to determine whether a change is physical or chemical.

In this process I want you to discuss the following:

• What types of changes are chemical and what types are physical? (Come up with examples for each)
• What types of evidence are you looking for in a physical change?
• What types of evidence would convince you that a chemical change has occurred?
• When you are stuck in a scenario where you are unsure, what other resources can you use to figure it out? A good example of this would be the sodium polyacrylate and water, what was it anyway?

Enrichment:

Find a video of a sweet physical or chemical change. Describe which it is. See if you can figure out how to embed a video into a blog post.