Blog 4.1 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?)

Tell whether each of your predictions was accurate or not. This should take at least four sentences in order to say if you were correct, and then why or why not.

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.

Blog 3.2 Properties of Ionic and Covalent Compounds

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?

Lab 3.1 Modeling of Molecules

As we know, all matter is made up of little particles. 

When a sample of material is known to use covalent bonds, the material is said to be “molecular,” or in other words, the material is made up of “molecules.”  A cluster of HCl molecules is shown below.  Molecules have an electrical charge of zero.

 

 

When a sample of matter is known to use ionic bonds, the material is said to be “ionic,” or in other words, the material is made up of “ions.”  A cluster of Al³⁺ and O^2- ions is shown below.  Ions have electrical charges on them.

 

One way of knowing whether a material is using ionic or covalent bonds is to test its melting point.  It is generally true that molecular substances have lower melting points than ionic substances.  For example, HCl melts at -115^oC while Al₂O₃ melts at 2072^oC. 

1.  Decide whether you think the attraction between ions is stronger than between molecules, or visa-versa.  Explain what evidence you are using from the information above, in order to make a conclusion about this.

2.   When HCl molecules are melted, do we still have HCl molecules, or are the molecules broken down into H and Cl atoms?  Explain based on your understanding of whether the process of melting is a physical or chemical change.

3.  When ionic substances are melted, they can conduct electricity.  When they are solids, they can not.  Explain why this is so.

4.  Molecular substances do not conduct electricity in either solid or liquid form.  Why not?

ENRICHMENT:  Research what a “polar” molecule is.  Find out whether or not water molecules are polar.  Draw a set of 4-5 water molecules showing how they arrange when touching each other.