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Homework - Unit 4

Assignment name Date due Points earned

Vocabulary for Unit 4

Graph Interpretation

Line Graph HW

The Commandments of Graphing Made Easy

Slope and Graphing Extrapolation

Graphing Scientific Data

Bond Energies

Electrolysis

Reaction Rates

Isotopes

Nuclear Chemistry Questions

Nevada’s Hidden Ocean of Radiation

Nuclear Decay Organizer

Nuclear Decay

Fission vs. Fusion

Summary:

The commandments of graphing

Be able to construct a graph and calculate the slope accurately with units Bond energy Know how the process of making and breaking bonds releases and stores energy Be able to explain how endothermic and exothermic reactions are related to bond energy Recognize that in all reactions energy is conserved Reaction rates Know how different factors affect the rate of reaction (concentration, temperature, pressure) Nuclear chemistry Be able to identify isotopes and find the number of subatomic particles in each Know how to find the average atomic mass of a group of isotopes Explain what happened to an atom when it emits radiation (goes through nuclear decay) Be able to identify three kinds of radiation Be able to predict products of nuclear reactions and decay processes Recognize key differences between fission and fusion

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Uni

t 4

Bond energy

Exothermic

Endothermic

Law of conservation of Energy

Concentration

Catalyst

Equilibrium

Isotope

Average atomic mass

Nuclear decay

Alpha

Beta

Gamma

Fission

Fusion

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Graph interpretation

A container of water is placed over a Bunsen burner and is heated. The scientist records the amount of energy (Heat in calories) they add to the system and the resulting temperature of the water. a Did the water consistently get warmer? b When did it increase the fastest? c If the heating was not constant when did it slow down? d Were there times where the temperature remained the same even though energy was added, if so when? e What might be occurring in “leg B” and “leg D” on this graph? Rachel keeps a record of the mass of her puppy as it grows. The records she has gathered are listed below: Age (months) 1 2 4 6 9 10 12 Mass (kilograms) 5 8 10 12 21 23 24

a. Plot the data

b. Title the graph (The title should always be the y variable vs. the x)

c. Draw a best fit line

a. Estimate the mass of the puppy when it was born.

b. Estimate the mass of the puppy at 8 months

c. Estimate the mass of the puppy at 13 months

d. Should your best-fit line go to the origin? Why or why not?

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The commandments of graphing made easy. Use the data on the opposite side to answer the following questions so you construct a perfect graph.

1. Use the graph paper provided

2. Title your graph and label the axis correctly with units

3. Find the correct scale:

a. Independent variable (X axis) ______________

b. Dependent variable (Y axis) _____________

c. Y axis data range: _________

i. Number of squares available: __________

ii. Scale for Y axis: (range / number of squares) _________

iii. Rounded up to an easy number: ________

d. X axis domain: _________

i. Number of squares available: __________

ii. Scale for X axis: (domain / number of squares) _________

iii. Rounded up to an easy number: _________

4. Fill up the graph. Use all the data provided and create a best-fit line.

Questions for after you construct your graph: (we will also do this as a class if you need help)

A. Calculate the slope (show all your work).

B. If the object travels 45.9 seconds what distance would it have covered? (Use your slope to figure this out.)

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Graph the following data. Be sure to include all of the 5 commandments of graphing.

Distance (m) Time (sec) Distance cont. (m) Time cont. (sec) 0.25 1 2.55 20 0.57 4 2.75 22 0.72 6 2.90 24 1.03 8 3.27 26 1.58 10 3.50 28 1.47 12 3.67 30 1.80 14 4.05 32 2.00 16 4.28 34 2.23 18 4.21 36

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Slope and Graphing Extrapolation Study the graphs of the following lines, pay close attention to the scales of both the x and y-axis and calculate the slopes of each using the slope formula.

Step one: label two places where the line intersect the graph paper with (x,y) coordinates Step two: solve for slope using: 𝑠𝑙𝑜𝑝𝑒 =   !"#$

!"#

0  5  10  15  20  25  30  

1   3   5   7   9   11  13  15  17  19  21  23  25  

Temperature  (*C)  

Time  (min)  

Temperature  Vs.  Time  

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1. Solve for x

2. Solve for x

3. If the object from the first graph on the previous page were allowed to travel for 7.3 hours how far would the object travel? (In this class we will solve problems like this by setting up the slope as an equality, but if you are comfortable using the formula y = mx + b then you may use that instead.)

4. Using the second graph from the previous page calculate the pressure that would result if the sample were heated to a temperature of 800 K

5. Using the third graph from the previous page:

a. Without doing any math estimate when the object would reach a temperature of 18oC.

b. Using the slope calculate at what time the sample would reach a temperature of 18oC.

c. Compare the two values (which do you think is more accurate and why?):

x3= 94

x12sec

= 5m300sec

x7.3hrs

= 10km1hr

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Graphing Scientific Data Experimental data provide information about the variables from specific measurements. Graphs can be prepared from data. A straight line or curve is drawn using the data points as a guide. The data points are not connected in a “dot-to-dot” manner. Rather, the line that best fits the data is drawn. Often scientists need to know what the value of a variable will be at a point that was not measured. Interpolation is a method used to approximate values that are between points of a graph. Extrapolation is a method for approximating values that are beyond the range of data. Data must be extrapolated when values needed are not in the range of the measurements obtained. The data in the table to the right were obtained from an experiment conducted to find out how the volume of a gas changes when scientists increase the temperature of the gas. Use this data to construct and interpret a graph.

Procedure: 1) Draw a graph on the graph paper provided 2) Mark the x-axis for the independent variable

and the y-axis for the dependent variable. 3) Plot a point for each temperature/volume set of

data in the table. 4) Draw the line that best frits the data points 5) Extend the line to include all temperatures

from 0K to 600K. Data Table:

Temperature (K) Volume (cm3) 0 0

100 57 210 124 273 152 280 174 360 206

(go up to a max of 600) (go up to a max of about 430)

Questions (to be answered AFTER making the graph):

1. What does extrapolate mean?

2. What does interpolate mean?

3. Suppose you had drawn the graph in a “dot-to-dot” fashion. Why would it be difficult to extrapolate form this type of graph?

4. Why isn’t it necessary for all the data points to be on the drawn line of the graph?

5. Write a sentence that describes the relationship between the temperature and the volume of a gas.

6. Use your graph to predict the values for the volume of a gas at 140K, 400K and 600K.

a. Why don’t we enter data points on the graph for these points?

7. Calculate the slope of your best fit line (show all work on next page)

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Slope Calculation

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Line Graph Homework

Find a LINE graph in a newspaper, magazine or off the Internet. Attach your graph to the paper and answer the following questions. You will not receive credit without the attached graph.

1. What is the source of your graph? (Where did you find it?) 2. What is the independent variable?

3. What is the interval (scale) for the independent variable? What are the units of measure?

4. What is the dependent variable?

5. What is the interval (scale) for the dependent variable? What are the units of measure?

6. Summarize the information that the graph tells you.

7. How does this graph help convey information?

8. In general does the graph follow our “commandments of graphing”? Explain.

9. Are there any mistakes or problems with the graph that makes it confusing? Be detailed and specific!

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Bond Energies

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Reaction Rates

1. What are the four major factors that affect reaction rate?

2. Why would a mixture of gases react faster when the volume they occupy is decreased?

3. Why would iron filings rust faster than an iron nail?

4. What is the effect of a catalyst on the required energy to achieve effective collisions?

5. Enzymes act as catalysts in our bodies. Have you ever noticed that your hands seem to get “stiff” when they get cold? The reason this happens is because the enzyme reactions causing the muscles to contract, __________ down when your hands are cold, so you can’t contract your muscles as fast, and your hands feel stiff! Decreasing temperature (decreases, increases) the rate of reaction.

6. Enzymes are in molds and bacteria that spoil food. Explain, using your knowledge of

factors affecting the rate of reaction, why food doesn’t spoil as fast when it is refrigerated as it would at room temperature.

7. Due to decomposition reactions with oxygen or carbon dioxide in the air, meat begins to feel slimy and smell spoiled. Explain, using your knowledge of chemical kinetics, why meat spoils less rapidly when left un-sliced.

8. Based on your knowledge of factors affecting the rate of reaction, why is there a danger of explosions in places such as silos and coal mines where there are large quantities of powdered, combustible materials?

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Isotopes – Atomic Structure Practice Sheet 1) What does the 18 in the symbol O-18 represent? Place a *star by each isotope in the table below; make sure to write their symbol correctly.

symbol protons electron neutrons atomic number

mass number

Ca

20

C

6 8

Pb

201

10

23

3 3

13 14

50 118

F

9 17

Mg

12 12

28 61

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Nuclear Chemistry Questions

1. What determines whether or not an atom is radioactive?

2. How does an unstable atom gain stability?

3. What part of an atom undergoes change during radioactive decay?

4. Explain the difference between an isotope and a radioisotope.

5. Where are most of the radioactive elements found on the periodic table?

6. How does a nuclear reaction differ from a chemical reaction?

7. Which subatomic particles are involved in a nuclear reaction; which is involved in a chemical reaction?

8. Which of the following will be the most stable? Which will be the least stable? Explain your answer. K-40 I-126 Zn-65 U-238

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Nevada's hidden ocean of radiation Toxic | Offcials take a new look at blast damage, as the state faces a water crisis November 13, 2009|Ralph Vartabedian YUCCA FLAT, NEV. — A sea of ancient water tainted by the Cold War is creeping deep under the volcanic peaks, dry lake beds and pinyon pine forests covering a vast tract of Nevada. Over 41 years, the federal government detonated 921 nuclear warheads underground at the Nevada Test Site, 75 miles northeast of Las Vegas. Each explosion deposited a toxic load of radioactivity into the ground and, in some cases, directly into aquifers. When testing ended in 1992, the Energy Department estimated that more than 300 million curies of radiation had been left behind, making the site one of the most radioactively contaminated places in the nation. During the era of weapons testing, Nevada embraced its role almost like a patriotic duty. There seemed to be no better use for an empty desert. But today, as Nevada faces a water crisis and a population boom, state officials are taking a new measure of the damage. They have successfully pressured federal officials for a fresh environmental assessment of the 1,375-square-mile test site, a step toward a potential demand for monetary compensation, replacement of the lost water or a massive cleanup. "It is one of the largest resource losses in the country," said Thomas S. Buqo, a Nevada hydrogeologist. "Nobody thought to say, 'You are destroying a natural resource.' " 1.6 trillion Gallons Polluted

In a study for Nye County, where the nuclear test site lies, Buqo estimated that the underground tests polluted 1.6 trillion gallons of water. That is as much water as Nevada is allowed to withdraw from the Colorado River in 16 years -- enough to fill a lake 300 miles long, a mile wide and 25 feet deep. At today's prices, that water would be worth as much as $48 billion if it had not been fouled, Buqo said. Although the contaminated water is migrating southwest from the high ground of the test site, the Energy Department has no cleanup plans, saying it would be impossible to remove the radioactivity. Instead, its emphasis is on monitoring. Federal scientists say the tainted water is moving so slowly -- 3 inches to 18 feet a year -- that it will not reach the nearest community, Beatty, about 22 miles away, for at least 6,000 years. Still, Nevada officials reject the idea that a massive part of their state will be a permanent environmental sacrifice zone. Access to more water could stoke an economic boom in the area, local officials say. More than a dozen companies want to build solar electric generation plants, but the county cannot allow the projects to go forward without more water, said Gary Hollis, a Nye County commissioner.

The problem extends beyond the contamination zone. If too much clean water is pumped out of the ground from adjacent areas, it could accelerate the movement of tainted water.

Application denied

When Nye County applied for permits in recent years to pump clean water near the western boundary of the test site, the state engineer denied the application based on protests by the Energy Department.(The department did not cite environmental concerns, perhaps to avoid acknowledging the extent of the Cold War contamination. Instead, federal officials said the pumping could compromise security at the test site, which is still in use.) "Those waters have been degraded," said Republican state Assemblyman Edwin Goedhart of Nye County, who runs a dairy with 18,000 head of livestock. "That water belongs to the people of Nevada. Even before any contamination comes off the test site, I look at this as a matter of social economic justice." In 1950, President Truman secretly selected the site for nuclear testing and withdrew the federally owned land from public use.

In early 1951, atomic blasts started lighting up the sky over Las Vegas, then a city of fewer than 50,000. Early atmospheric tests spawned heavy fallout, and some areas are still so radioactive that anybody entering must wear hazardous-material suits. Later tests were done underground, leaving hundreds of craters that resemble otherworldly scars. Each of the underground detonations -- some as deep as 5,000 feet -- vaporized a huge chamber, leaving a cavity filled with radioactive rubble. About a third of the tests were conducted directly in aquifers, and others were hundreds or thousands of feet above the water table. Federal scientists say contamination above the aquifers should remain suspended in the perpetually dry soil, a contention that critics say is unproven. In the hottest zones, radioactivity in the water reaches millions of picocuries per liter. The federal standard for drinking water is 20 picocuries per liter. Federal officials say they don't know how much water was contaminated. Whatever the amount, they say, extracting it would be prohibitively expensive, and even if the radioactive material could be separated, it would have to be put back in the ground elsewhere. Although radiation levels in the water have declined, the longer-lived isotopes will continue to pose risks for tens of thousands of years. The Energy Department has 48 monitoring wells at the site and began drilling nine deep wells in the summer. Bill Wilborn, the Energy Department's water expert at the site, said the water is moving about two-thirds of a mile every 1,000 years from low-lying Yucca Flat, where 660 nuclear tests were conducted. Although Nevada has not pressed for compensation or replacement water so far, public officials say they are considering such action.

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Nuclear Decay Organizer

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Alp

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Nuclear Decay

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Fission vs Fusion Nuclear Weapons There are two main types of nuclear weapons: atomic bombs, which are powered by fission reactions similar to those in nuclear reactors [power plants], and hydrogen bombs, which derive their explosive power from fusion reactions. An atomic bomb slams together two pieces of fissionable material, usually uranium-235 or plutonium-239, creating critical mass. This releases its energy instantaneously as atoms inside it split in an uncontrolled chain reaction. On August 6, 1945, an atomic bomb called Little Boy was dropped on the Japanese city of Hiroshima, followed three days later by another, called Fat Man, on Nagasaki. Hydrogen bombs fuse together hydrogen atoms to form heavier helium atoms, releasing far more energy than a fission bomb. Two isotopes of hydrogen are used – deuterium (2 neutrons) and tritium (3 neutrons). Hydrogen bombs have never been used in war and are thousands of times more powerful than atomic bombs. Directions: #1-8 Identify each as a fusion , fission , or both kinds of reactions:

1. Used in nuclear power plants:

2. Occurs on the sun:

3. More power per gram:

4. A larger nucleus divides to make a smaller nucleus:

5. Two hydrogen atoms fuse to make a helium atom: ______________________________

6. A critical mass is necessary to explode: _________________________________

7. An atomic bomb: ____________________________

8. The picture below shows ____________________________

Short answer questions #9-12. Write a sentence or two on each.

9. Why can’t we use fusion reaction in a nuclear power plant?

10. What is the downside to fission reactions used in power plants?

11. How is electricity generated from nuclear power plants?

12. Is cold fusion possible?

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Complete the following fission and fusion nuclear equations. Indicate if the equation represents fission or fusion (circle one) 1. Fission or fusion 2. Fission or fusion 3. Fission or fusion 4. Fission or fusion 5. Fission or fusion 6. Fission or fusion 7. Fission or fusion 8. Fission or fusion

231 91 Pa ! Ir + ________ 192

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Pu ! Pr + ________

He + H ! _______

U ! Te + ________

Db ! Mo + Si + ________

244 94

141 59

Be + C ! _______

Fe + Ni ! _______

Hs ! O + Be + ________

4 2

12 6

9 4

238 92

128 52

2 1

56 26

59 28

262 105

265 108

96 42

16 8

28 14

9 4