Activity 3 1/19/11 Crystal Structures

Show crystal structures fo NaCl (sodium chloride)and CaCO₃ (calcium carbonate). what is the melting point for these two materials.

NaCl: melting point= 801⁰C/1074 K

CaCO₃: melting point=  825^o C/ 1098 K(calcite)  1339^oC/ 1612K (aragonite)

Activity 2 1/19/11 Weather and Bernoulli Principle

Describe some common weather occurrences in relation to the gas laws and characteristics we have been exploring.

                When temperature increases, volume increases; this applies when the sun produces heat, causing temperature to increase which causes the expansion of the molecules to increase (volume) which creates wind. When temperature decrease, volume decreases; this applies when clouds cover up heat making the air cooler and wind is being forced in an area (contraction).

                Global Warming: increase in world’s temperature caused by additional heat being trapped by greenhouse gases. Inverse relationship: temperature increases, volume decreases.

What is the Bernoulli Principle, provide an example or application of this.

                Bernoulli Principle states that a fluid’s flow (that has no viscosity (not thin or thick)), has an increase in the speed of the fluid occurs simultaneously with a decrease in pressure or decrease in the fluid’s potential energy. So when the pressure of a fluid decreases the speed of the fluid increases. High-speed flow is associated with low pressure, and low-speed flow is associated with high pressure.

http://library.thinkquest.org/27948/bernoulli.html  animation

http://www.centennialofflight.gov/essay/Dictionary/bernoulli/DI9.htm

Activity 1 1/19/11 Ideal Gas Law

What is the tire pressure at -20°F compared to 90°F, assuming the starting pressure was 32 psi?
 25.6psi


  32psi     =       ?psi
305.2K            244.3K

( 244.3K) ( 32psi )    =    (   ?psi)         ( 244.3K)

               (305.2K )          ( 244.3K)

                      

                                               244.3K cancel each other on this side

 ( 244.3K) ( 32psi )    =       ?psi

                (305.2K)         

32psi divide into 305.2K, then multiply 244.3 K, result is 25.6 PSI

Homework 1/18/11 Water Freezing

Room Temp	Freezing Point Temp	Salt Amount	Time	Time	Inches (height) Before	Inches (height) After
20°C	-7°C	3tsp	8:30  20°C 9:00 13°C 9:15  10°C 9:30   6°C	10:00  6°C 10:15  6°C 10:45  6°C 12:45  -7°C	2in	2.45in
20°C	-4°C	1 ½ tsp	8:30 20 °C 9:00 11°C 9:15  4°C 9:30   4 °C	10:00 2°C 10:15  -1 10:45   -1°C 11:15  -4°C	2in	2.78in
20°C	0°C	0tsp	8:30 20°C 9:00 6°C 9:15 0°C 9:30 N/A	10:00  N/A 10:15  N/A 10:45  N/A 11:00  N/A	2in	2.3in

1.) How much does water expand when frozen?

From my own experiment the water expanded from about 0.3 inches to about 0.78 inches when frozen.

2.) When is water the smallest? at what temperature.

From doing my experiment water was the smallest when it was at room temperature.

3.) What happens when salt is added to the water?

When salt gets added to water, it causes the water to break down the salt molecules, which slows down the process in which water freezes.

4.) Does the amount of salt added effect the freezing point?

I believe that the amount of salt added to water effects the water’s freezing point. I believe this because when I added more salt to my water it took longer for the water to freeze compared to my cup that did not have salt mixed with the water. The more salt I added, the longer it seemed to take for the water to completely freeze.

Activity 2 1/18/11 Molecular Masses

List the molecular masses of carbon dioxide, oxygen, and helium. Explain how you get this from the Periodic Table.

             Carbon dioxide: CO₂   C=12    O=16  O₂=32    12+32=44

                        CO₂ = 44

            Oxygen: O₂        O=16   O₂=32

                        O₂=32

            Helium: He = 4

            Water: H₂O     H=1    H₂= 2       O=16     16+2=18

                        H₂O= 18

    I had to use the atomic mass that is found on the periodic table.

Activity 1 1/18/11 Burning Candle observations

What is burning? Show the chemical formula and an image of the structure.

            The wax of the candle is burning and the wick is burning at a much slower time frame then wax.

  The flames are caused as a result of a fuel undergoing combustion; which is burning.

The fuel from the lighter combines with oxygen which forms the flame in which lights the candle wick. When you light the wick, you are providing a heat source and oxygen from the air. The smoke formed contains carbon dioxide and water and also some soot from the inefficient combustion.

Write the chemical reaction.  C₂₅H₅₂ + O₂ → CO₂ + H₂O 

                                                                               

Write the balanced chemical reaction.   C₂₅H₅₂ + 38 O₂ → 25 CO₂ + 26 H₂O

                A balanced chemical reaction is keeping track of carbon atoms- when burning wax, we are not burning away the carbon atoms.

Butane: C₄H₁₀   +    O₂          --->    H₂O   +  CO₂

                        C₄H₁₀   +   7 O₂          --->   6 H₂O   + 4 CO₂

2C₄H₁₀   +   13 O₂          --->   10 H₂O   + 8 CO₂   - two butane molecules

                                Oxygen: 10                     16oxygen             26 oxygen

Homework 1/13/11

Explain what happened in that mountain village we described in class. Your explanation will need to include detail that includes density and molecular weight of gases.

We discussed how there was a village in Africa in between a mountain and an old volcano with a lake on the other side of it. This old volcano had a lot of CO2 present. In this village, there was a house and people who had died. New people came and found these people dead, but were confused on how they died. There was no visible reason on why these people died. So the question is, how did they die? 


The CO2 drifted down into the village, which is a low-lying area. Then high CO2 levels get trapped in this low-lying area in between the mountain and the old volcano, causing the people to take in more CO2 then a body needs; causing them to die; "it typically becomes diluted to low concentrations very quickly whether it is released continuously from the ground or during episodic eruptions" http://volcanoes.usgs.gov/hazards/gas/index.php. If someone was so breathe in air that has more then 30% CO2, this can quickly induce unconsciousness and even cause death to a person.


CO2 gas is much heavier than air, giving it a molecular weight of 44.01; which means CO2 is more dense then the air (oxygen). Due to the people living in a trapped in area, they were not able to receive enough oxygen to rid the high levels of CO2.


The new people coming into the village could not find any identifiable source on why these people died because CO2 is a odorless and colorless gas.

http://volcanoes.usgs.gov/hazards/gas/index.php