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My report on "Chemical Reactions and Stoichiometry"
My report on "Chemical Reactions and Stoichiometry"
Student name: Kelly Birkeland
Teacher name: Dr_R_Belton
School: Northern Michigan University
Submission Time: 9/23/12 2:39 PM
Page 1 : http://mw2.concord.org/public/part2/chemreact/page1.cml
1. When does a chemical reaction occur? (Note: You can reset the model or even play it backwards .)
(a) Any two atoms can form a bond at any time.
(b) When two unbonded atoms collide with each other.
(c) When any two atoms hit each other even if they have already formed bonds to other atoms.
(d) Sometimes, when bonded atoms collide with something else, the bond breaks.
(e) Both B and D are correct.
My answer is (e) (1:28:16 PM)
2. If the atoms are heated to a high temperature:
(a) bonds tend to form rather than break.
(b) bonds tend to break rather than form.
(c) on average there are just as many atoms without bonds as atoms with bonds.
(d) the temperature seems to have no effect on bonding.
My answer is (b) (1:28:56 PM)
Page 2 : http://mw2.concord.org/public/part2/chemreact/page2.cml
1. How does the atom concentration affect the rate of the chemical reaction?
(a) Concentration has no effect.
(b) Increased concentration = increased reaction rate.
(c) Increased concentration = decreased reaction rate.
My answer is (b) (1:30:57 PM)
2. Explain the connection between concentration, collisions, and reaction rate.
With an increase in concentration of molecules, the closer they become to one another in proximity. This causes for more collisions between molecules and therefore increases the reaction rate. (1:32:50 PM)
Page 3 : http://mw2.concord.org/public/part2/chemreact/page3.cml
1. How does the temperature affect the rate of the chemical reaction?
(a) Temperature has no effect.
(b) Higher temperature = increased reaction rate.
(c) Higher temperature = decreased reaction rate.
My answer is (b) (1:32:56 PM)
2. Explain the connection between temperature, collisions, and reaction rate.
With an increase in temperature, the molecules move with greater speed in their random patterns causing for more collisions. Therefore, more collisions increase the reaction rate. (1:34:03 PM)
3. What do you think would happen if you could raise the temperature to a much higher level than is allowed using the slider above?
(a) It will just form bonds even faster.
(b) No bonds will form.
(c) Bonds will form, but they will also break apart.
My answer is (c) (1:34:03 PM)
Page 4 : http://mw2.concord.org/public/part2/chemreact/page4.cml
1. What changes did you make to the size of the container and the temperature to reach 80% completion the fastest way possible? Explain why that worked.
I made the container size slightly smaller and I increased the temperature a little bit to increase the movement of the molecuels but not too much to exceed 80% completion. This worked because the environment allowed for the molecules to create bonds, but not too only prompt them to break them apart. (1:49:30 PM)
2. Why shouldn't you set the temperature for the highest possible value if your goal is to have about 80% of the atoms bonded to form molecules?
If the temperature was increased to the highest possible, then reaching 80% of the molecules being bonded would not be possible because they would be breaking apart more than bonding. (1:50:36 PM)
Page 5 : http://mw2.concord.org/public/part2/chemreact/page5.cml
1. Describe what happens in the following reaction: A + B2 AB + B
One atom of A and one molecule of B2 (the reactants), chemically react to form one molecule of AB and one atom of B (the products). (1:55:52 PM)
Page 6 : http://mw2.concord.org/public/part2/chemreact/page6.cml
1. Which hydrogen to chlorine ratios give a reaction that forms HCl with nothing left over? (Select all that work.)
(a) 1 hydrogen : 1 chlorine
(b) 2 hydrogen : 1 chlorine
(c) 2 hydrogen : 2 chlorine
(d) 2 hydrogen : 3 chlorine
(e) 4 hydrogen : 4 chlorine
My answer is (a) (c) (e) (2:01:32 PM)
2. What is the correct balanced equation for making water from hydrogen and oxygen?
(a) H2 + O2 --> H2O
(b) 2 H2 + O2 --> H2O
(c) 4 H2 +2 O2 --> 4 H2O
(d) 2 H2 + O2 --> 2 H2O
(e) 2 H2 +2 O2 --> 4 H2O
(f) H2 +2 O2 --> H2O
My answer is (d) (2:07:28 PM)
Page 7 : http://mw2.concord.org/public/part2/chemreact/page7.cml
1. Which is the limiting reactant in the 2nd reaction?
(a) fuel
(b) oxygen
(c) both are limiting
My answer is (a) (2:08:08 PM)
2. Explain why it is hard to get ALL of the fuel to react if you use exactly the right ratio of fuel to oxygen. hint
If exactly the right ratio of fuel to oxygen is used, it is hard to get all of the fuel to react because as the reaction occurs, and ehaust is produced, then it becomes more difficult for the fuel and oxygen to collide and bond. The movement of the molecules becomes inhibited therefore becoming difficult to bond. (2:10:17 PM)
3. To power your car a specific amount of gasoline (fuel) is mixed with air (containing oxygen). If the mixture is not right, then your car will not have much power, or it will be spitting out lots of unburned fuel as a pollutant, or both. What do you think is the best fuel/oxygen mixture to optimize power and reduce pollution (i.e. get the most fuel in the cylinder which can be burned efficiently)?
(a) use the perfect ratio of fuel to oxygen as indicated by the chemical equation
(b) use extra fuel, making oxygen the limiting reactant
(c) use a lot of extra oxygen, making the fuel a very limiting reactant
(d) use a little extra oxygen, making the fuel the limiting reactant
My answer is (d) (2:10:33 PM)
Page 8 : http://mw2.concord.org/public/part2/chemreact/page8.cml
1. Reaction 1 is what type of reaction:
(a) synthesis
(b) decomposition
(c) single displacement
(d) double displacement
My answer is (b) (2:11:49 PM)
2. Reaction 2 is what type of reaction:
(a) synthesis
(b) decomposition
(c) single displacement
(d) double displacement
My answer is (a) (2:12:36 PM)
3. Reaction 3 is what type of reaction:
(a) synthesis
(b) decomposition
(c) single displacement
(d) double displacement
My answer is (c) (2:13:33 PM)
Page 9 : http://mw2.concord.org/public/part2/chemreact/page9.cml
1. Which of the following affect the rate of reaction?
(a) concentration of reactants
(b) temperature of reactants
(c) boiling point of reactants
(d) both A and B
(e) none of the above
My answer is (d) (2:13:45 PM)
2. Explain your answer for the previous question about factors affecting reaction rates.
The concentration and temperature of reactants affects the reaction rates by increasing the opportunity for the molecules to collide and form bonds. The more molecules there are and higher the temperature it is, the higher the reaction rate. (2:21:05 PM)
3. The process by which food rots is ultimately driven by chemical reactions. Why does refrigerating food make the food last longer? (Be sure to explain it at the molecular level.)
Due to the food being kept at a colder temperature, it decreases the reaction rate. The decreased temperature decreases the molecular movement and therefore decreases the opportunity for the molecules to collide and bond. The less bonding of chemical reactions that occur, the longer time the rotting will take to begin. (2:34:15 PM)
4. Which chemical equation below is shorthand for the following description? One molecule of methane (CH4) reacts with two molecules of oxygen (O2) to form one molecule of carbon dioxide (CO2) and two molecules of water (H2O):
(a) CH4 + O2 --> CO2 + H2O
(b) 2 CH4 + 4 O2 --> 2 CO2 + 4 H2O
(c) CH4 + 2 O2 --> CO2 + 2 H2O
(d) CH4 + 2 O2 --> 2 CO2 + 2 H2O
My answer is (c) (2:21:30 PM)
5. Aluminum reacts with oxygen to form aluminum oxide, a thin non-reactive coating that prevents aluminum from further rusting. The UNBALANCED chemical equation is: Al + O2 Al2O3. What is the correct BALANCED chemical equation?
(a) 8 Al + 6 O2 --> 4 Al2O3
(b) 2 Al + 3 O2 --> Al2O3
(c) 4 Al + 3 O2 --> 2 Al2O3
My answer is (c) (2:34:18 PM)
6. Some dry powder fire extinguishers contain baking soda and use the following reaction to produce carbon dioxide (CO2), which helps to smother the fire: 2 NaHCO3 Na2CO3 + H2O + CO2. What type of reaction is this?
(a) synthesis
(b) decomposition
(c) single displacement
(d) double displacement
My answer is (a) (2:36:36 PM)
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