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73 Cards in this Set
- Front
- Back
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What is chemistry?
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Chemistry is, quite simply, the study of matter . Chemistry, then, is the study of nearly everything!
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There is one thing that has no mass and takes up no space. What is it?
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What very common thing that is surrounding you right now has no mass and takes up no space? The answer is: light.
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True or False: Air has mass and takes up space.
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True
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So what is light, if it is not matter?
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It is pure energy!!
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How do we study matter?
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Well, the first thing we have to be able to do in order to study matter is to measure it. If I want to study an object, I first must learn things like how big it is, how heavy it is, and how old it is.
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When a scientist is reporting information, what must he always have with a number?
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Scientists should never simply report numbers. They must always include UNITS with those numbers, so that everyone knows exactly what those numbers mean.
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What is the difference between mass and weight?
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Mass measures how much matter exists in an object. Weight, on the other hand, measures how hard gravity pulls on that object.
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True or False? Since weight is a measure of how hard gravity pulls, an object weighs different amounts depending on where that object is.
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True.
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In order to use a prefix unit in the metric system, what do you do?
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you add a prefix to the base unit
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True or False? In the metric system the prefixes mean the same thing regardless of the physical quantity that you want to measure.
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True!
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The metric system is more logical and versatile than the English system. True or False? Why?
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True. You don't have to worry about conversions, you just have to remember what the prefix means, and also there are more prefix units than there are alternative units in the English system.
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What steps do you take in converting units?
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FACTOR-LABEL METHOD:
1. First write the known measurement in fraction form by putting it over one. 2. Then find the relationship between the unit we have and the unit to which we want to convert. 3. We will then use that relationship to make a fraction that, when multiplied by our first fraction, cancels out the unit we have and replaces it with the unit we want to have. |
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A student measures the mass of a book as 12,321 g. What is the book's mass in kg?
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12,321 kg
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If a glass contains 0.121 L of milk, what is the volume of milk in mL?
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121mL
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On a professional basketball court, the distance from the three-point line to the basket is 640.08 cm. What is this distance in meters?
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6.4008 m
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True or False? The factor-label method can only be used within systems of units... it can not be used to convert between them.
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FALSE. The factor-label method CAN be used to convert between systems of units as well as within systems of units.
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How many slugs are there in 123.5 kg?
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8.46 sl
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If an object occupies 3.2 gallons of space, how many liters of space does it occupy?
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12.096 L
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If you have no relationship between the unit you are given and the unit to which you will convert, what do you do?
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first convert the given unit to the base unit
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A balloon is blown up so that its volume is 1,500 mL. What is its volume in kL?
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0.0015 kL
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If the length of a race car track is 2.0 km, how many cm is that?
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200,000 cm
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How many Mg are there in 10,000,000 mg?
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0.01 Mg
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What are the rules for using units in mathematical expressions?
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1. Adding and Subtracting Units: When adding and subtracting units, the most important thing to remember is that the units you are adding or subtracting must be identical: You cannot add grams and liters.
2.Multiplying and Dividing Units: When multiplying and dividing units, it doesn't matter whether or not the units are identical. |
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The metric unit for volume is the liter, but there are others as well. What are some?
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Another metric unit for volume is the cm 3. Additionally, m 3 (cubic meters) and km 3 (cubic kilometers) are also possible units for volume.
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1 cubic centimeter is the same as 1 milliliter. (very important, memorize this)
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1 cubic centimeter is the same as 1 milliliter.
(Very important, memorize this) |
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A braggart tells you that he walks 100,000 cm each day. He expects you to be impressed with such a big number. Should you be impressed? Convert the distance measurement to miles in order to determine whether or not to be impressed. (HINT: Earlier in this module, you were told how many inches are in a foot and how many feet are in a mile. You must use those numbers to solve this problem.)
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0.621371 miles
Since that's not even 1 mile, you should not be impressed by the braggart. |
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How many cm3 are in 0.0045 kL?
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4,500 cm3 (mL and cm3 equivalent)
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The area of a room is 16 m2. What is the area of the room in mm2?
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16,000,000 mm2
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The first rule for measuring with a ruler is:
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The first rule for measuring with a ruler is to start at “1,” not “0.”
This is slightly more accurate, and accuracy is important! |
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When using a measuring device that has a scale on it, what do you do?
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First, determine what the dashes on the scale mean.
Then, try to estimate in between the dashes if the object you are measuring does not exactly line up with a dash. That gives you as accurate a measurement as possible. |
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Since chemists spend a great deal of time mixing liquids, volume is often a very important factor and must be measured. What useful tool is frequently used for this?
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One of the most useful tools to measure volume is the graduated cylinder.
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True or False? It is easy to measure with a graduated cylinder as the markings on the side make measuring the flat surface of the liquid inside the cylinder easy to see!
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FALSE. It is easy to use the graduated cylinder, BUT the liquid does NOT have a flat surface to measure by!
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When liquid is poured into a cylinder, the liquid tends to creep up the edges of the cylinder. Why?
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This is because there are attractive forces between the liquid and the cylinder.
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In order to determine the volume of the liquid that is in any graduated cylinder, you must read the level of the liquid from ........... where?
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the bottom of the meniscus
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Thus, the precision of your measurement depends completely on ..............What?
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the measuring device you use!
The smaller the difference in the dashes on the scale, the more precise your answer will be. |
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The accuracy of your measurement depends on how carefully and correctly you ........... what?
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used the measuring device
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True or False? A measurement's precision depends upon the instrument, whereas a measurement's accuracy depends upon the person doing the measurement.
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True
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Since a measurement's precision depends on the instrument used, the only way to improve your precision is to get a better instrument. However, there are other ways to improve your accuracy. Name them.
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1. First, you can make sure you understand the proper methods of using each instrument at your disposal.
2. Second, you can practice making measurements, which will help you in being careful. 3. make your measurement several times and average the results. An even better way of assuring accuracy is to have several different people make the measurements and average all of their answers together |
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A digit within a number is considered to be a significant figure if:
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i. It is non-zero OR
ii. It is a zero that is between two significant figures OR iii. It is a zero at the end of the number and to the right of the decimal point |
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How many significant figures are in the following measurement?
3.0220 cm |
All three non-zero digits are significant figures as are both zeros. One zero is between two significant figures while the other is at the end of the number to the right of the decimal. Thus, there are five significant figures.
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How many significant figures are in the following measurement?
0.0060 m |
The first three zeros are not significant because they are not between two significant figures. The six is a significant figure as is the last zero because it is at the end of the number to the right of the decimal. Thus, there are two significant figures.
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How many significant figures are in the following measurement?
1.00450 L |
All digits are significant figures here. The first two zeros are between significant figures and the last one is at the end of the number to the right of the decimal. Thus, there are six significant figures.
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How many significant figures are in the following measurement?
61.054 kg |
All digits are significant figures. The zero is between two significant figures. Thus, there are five significant figures.
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If you report the length as 3 cm, that means the ribbon could be as short as 2.5 cm or as long as 3.4 cm. Both of those measurements round to 3. So what SHOULD you report the measurement as?
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3.00 cm
Thus, the ribbon is somewhere between 2.995 and 3.004 cm long |
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As numbers get very large, it becomes more difficult to report their precision properly. So how do you report them?
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By using scientific notation!
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Scientific notation always has a number with a decimal point right after the first digit times a ten raised to some power. True or false?
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True
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When putting a large number into scientific notation, all you need to do is ......... what?
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When putting a large number into scientific notation, all you need to do is count the number of spaces the decimal point needs to move, and raise the ten to that power.
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Why do we use scientific notation?
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Also called "mathematical shorthand'" it makes writing down very large or very small numbers easier.
Scientific notation also gives us a way to make zeros significant if they need to be. |
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Convert the following number into scientific notation.
26,789,000 |
2.6789 x 10 to the 7th power
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Convert the following number into scientific notation.
123 |
1.23 x 10 to the 2nd power
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Convert the following number into scientific notation.
0.00009870 |
9.870 x 10 to the -5th power
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Convert the following number into scientific notation.
0.980 |
9.80 x 10 to the -1 power
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Convert the following number from scientific notation to decimal form.
3.456 x 10 to the 14th power |
345,600,000,000,000
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Convert the following number from scientific notation to decimal form.
1.2341 x 10 to the 3rd power |
1234.1
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Convert the following number from scientific notation to decimal form.
3.45 x 10 to the -5th power |
0.0000345
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Convert the following number from scientific notation to decimal form.
3.1 x 10 to the -1 power |
0.31
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What is the rule for Adding and Subtracting with Significant Figures:
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When adding and subtracting measurements, round your answer so that it has the same precision as the least precise measurement in the equation.
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What is the rule for Multiplying and Dividing with Significant Figures:
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When multiplying and dividing measurements, round the answer so that it has the same number of significant figures as the measurement with the fewest significant figures.
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The definitions of the prefixes in the metric system and the integers we use in fractions are not considered when determining the significant figures in the answer.
Memorize this rule. |
The definitions of the prefixes in the metric system and the integers we use in fractions are not considered when determining the significant figures in the answer.
Memorize this rule. |
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Why is density a very important quantity in chemistry?
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It gives you an idea of how tightly packed the matter is in an object.
Density gives us a way to determine exactly how much heavier one object is compared to another. |
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Every substance on earth has its own characteristic density.
True or False? |
True.
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What are two important things about studying chemistry?
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1. First, many chemistry problems require a great deal of algebra in order to solve. Thus, you must be pretty familiar with algebra to be successful at chemistry
2. Second, you must always watch your units. Be sure that units cancel when they should and do not cancel when they shouldn't. The best way to do this is to write down all of your units in every equation. |
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The density of silver is 10.5 grams per cm3. If a jeweler makes a silver bracelet out of 0.081 kg of silver, what is the bracelet's volume in mL?
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7.7 mL
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A gold miner tries to sell some gold that he found in a nearby river. The person who is thinking about purchasing the gold measures the mass and volume of one nugget. The mass is 0.319 kg and the volume is 0.065 liters. Is this nugget really made out of gold? (Remember that the density of gold is 19.3 grams per mL)
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4.9 g/mL
The answer can have only 2 significant figures, since 65 has only 2 significant figures. Since the density did not work out to be 19.3 grams per mL, then we know that this is not gold. In fact, this density is equal to the density of iron pyrite, also known as “fool's gold” because it looks a lot like gold but has little value. |
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Which of the following contains no matter?
a. A rock b. A balloon full of air c. A balloon full of helium d. A lightning bolt |
Pretty much everything except light contains matter. Since (d) is the only thing on the list that is
just light, the lightning bolt (d) has no matter |
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List the base metric units used to measure length, mass, time, and volume.
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Length is measured in meters, mass is measured in grams, time is measured in seconds, and volume
is measured in liters. |
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In the metric system, what does the prefix .centi. mean?
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. The prefix “centi” means 0.01, or one hundredth.
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Which has more liquid: a glass holding 0.5 kL or a glass holding 120 mL?
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Since a kL is equal to 1,000 L and a mL is only equal to 0.001 L, the glass holding 0.5 kL has more
liquid in it. |
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Two students measure the mass of a 502.1 gram object. The first student measures the mass to be
496.8123 grams. The second measures the mass to be 501 grams. Which student was more precise? Which student was more accurate? |
.Assuming both students reported the proper number of significant figures, the first student was
more precise (because that measurement has more places to the right of the decimal), but the second student was more accurate (because that measurement is closer to the correct value). |
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. How many significant figures are in the following numbers?
a. 0.0120350 b. 10.020 c. 12 d. 3.40 x 10^3 |
a. The first two zeros are not significant, but the other two are. Thus, there are 6 significant figures.
b. All of the zeros are significant. Thus, there are 5 significant figures. c. There are 2 significant figures. d. The zero is significant. Thus, there are 3 significant figures |
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A student measures the mass of an object as 2.32 grams and its volume as 34.56 mL. The student
then calculates the density to be 0.067129629. There are two things wrong with the student.s value for density. What are they? |
The student’s value for density has far too many significant figures, and it has no units attached.
Either of these things would make the student’s answer wrong. |
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Why does ice float on top of water?
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Ice floats on water because its density is lower than that of water.
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Lead has a density of 11.4 grams per mL, whereas gold has a density of 19.3 grams per cc. If I
were to make two identical statues, one out of gold and the other out of lead, which would be heavier? |
The golden statue would be heavier because the density of gold is greater than that of lead.
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