welcome to class. my name is charlie arbuiso and i will be your chemistry teacher. copy the...
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Welcome to class.My name is Charlie Arbuiso and I will be your chemistry teacher.
Copy the objective, and get ready to learn… Put the other papers away now.
1. Print the Objective: The synthesis of dihydrogen monoxide
Since it’s a chemistry class, let’s examine what we are dealing with…
2. dihydrogen monoxide =
3. Its formula is written as ____________________
4. ____ is the symbol for ________________________
5. ____ is the symbol for _________________________
6. The Word equation for this reaction is:
______________ and ________________ yields _________________________
7. The Skeleton equation (proper chemistry symbols, but not balanced yet):
_______ + _______ __________________
Since it’s a chemistry class, let’s examine what we are dealing with…
2. dihydrogen monoxide = 2 hydrogen atoms and 1 oxygen atom
3. Its formula is written as H2O (note the “2” is a subscript!)
4. H is the symbol for Hydrogen
5. Ois the symbol for oxygen
6. HYDROGEN and OXYGEN yields DIHYDROGEN MONOXIDE (WATER)
7. The Skeleton equation (proper chemistry symbols, but not balanced yet):
H + O H2O
Something that you didn’t know, and couldn’t know is that both hydrogen and oxygen are atoms that are not happy being single. They exist in nature in the pure form only as paired partners, like H2 and O2. Seven atoms are like this. You’ll learn them.
So let’s fix this symbol equation to a skeleton equation:
8. H + O H2OMath counts. Keeping track of atoms counts. This equation is not “balanced”. Not balanced means BAD. We need to fix that.
(you should not be able to do this, so don’t sweat, just copy for now)
9. H2 + O2 H2OThis is called a balanced chemical equation, the same amount of atoms on the start side of the reaction, and at the end.
10. copy this : (4 H atoms + 2 O atoms form into the same 4 H’s + 2 O’s but they are combined differently – that’s chemistry!)
Something that you didn’t know, and couldn’t know is that both hydrogen and oxygen are atoms that are not happy being single. They exist in nature in the pure form only as paired partners, like H2 and O2. Seven atoms are like this. You’ll learn them.
So let’s fix this symbol equation to a skeleton equation:
8. H2 + O2 H2OMath counts. Keeping track of atoms counts. This equation is not “balanced”. Not balanced means BAD. We need to fix that.
(you should not be able to do this, so don’t sweat, just copy for now)
9. 2H2 + O2 2H2OThis is called a balanced chemical equation, the same amount of atoms on the start side of the reaction, and at the end.
10. copy this : (4 H atoms + 2 O atoms form into the same 4 H’s + 2 O’s but they are combined differently – that’s chemistry!)
Now we need to add phase symbols, there are three phases of matter in our course.
11. What are phase symbols? ________________
12. Rewrite this balanced equation with phase symbols now.
2H2 + O2 2H2O
H2 gas + O2 gas in the
air
Now we need to add phase symbols, there are three phases of matter in our course.
11. What are phase symbols? They tell if the matter is solid, liquid or gas (there’s a few more, but not today, okay?)
12. Rewrite this balanced equation with phase symbols now.
2H2(G) + O2(G) 2H2O(G)
H2 gas + O2 gas in the
air
This will be a fun, memorable chemical reaction.
14. It’s called the synthesis of dihydrogen monoxide, or wata.
It will happen very fast, and will release lots of energy. Lots.
So much I have to teach you safety now, before we can continue.
You will not get hurt, but it is rather loud.
BANG! 15. What do we call a chemical reaction that gives off or emits energy?
This will be a fun, memorable chemical reaction.
It’s called the synthesis of dihydrogen monoxide, or wata.
It will happen very fast, and will release lots of energy. Lots.
So much I have to teach you safety now, before we can continue.
You will not get hurt, but it is rather loud.
BANG! 15. What do we call a chemical reaction that gives off or emits energy? EXOTHERMIC
16. Let’s write out the fully balanced thermochemical reaction…
2H2(G) + O2(G) 2H2O(G) + energy
17 (copy this) The synthesis of water is exothermic. Hydrogen and oxygen are elements. Water is a compound. Chemistry is the study of matter and how matter acts and reacts.
Homework:1. Read the handout for the course 2. Fill in the student data form, with parents3. Bring back the student data form, filled in, and with your parent’s signature
4. Get a loose-leaf binder and some paper. NO SPIRAL NOTEBOOKS for chemistry.
5. Tell your family about making wata and how much you will love this class.
Measurement Class 1
OBJECTIVE: To learn to distinguish between qualitative and quantitative measures, and between error and percent error; finally, to calculate percent error.
Paper is cheap. Knowledge is valuable.
Let’s have some fun, guess my weight.
Measure my mass, using your eyes and mind as your tools.
In science we measure (and estimate) all the time.
18. Write your answer down.
What were your guesses? Fast and loud.
Your eye “measurements” in pounds
19. On the bathroom scale, what is the ACTUAL mass of your teacher in pounds? ______
20. Measurements that are close to the correct weight are called ______________
21. Measurements that are close together (close to correct or not) are called: ____________
22. In our class we will measure our best to be _______________________
What were your guesses? Fast and loud.
Your eye “measurements” in pounds
19. On the bathroom scale, what is the ACTUAL mass of your teacher in pounds?
20. Measurements that are close to the correct weight are called ACCURATE
21. Measurements that are close together (close to correct or not) are called: PRECISE
22. In our class we will measure our best to be both ACCURATE + PRECISE
Accurate measurements are close to the actual or correct measure.
Precise measurements are close together.
23. If your measures are precise, your tool is ______________
Precise and accurate together is great.
Precise alone means that your tool is good.
24. Measurements that are not precise means that your ________________________________________ working well.
Accurate measurements are close to the actual or correct measure.
Precise measurements are close together.
23. If your measures are precise, your tool is CONSISTENT
Precise and accurate together is great.
Precise alone means that your tool is good.
24. Measurements that are not precise means that your
tool (or you) are not working well.
25. Qualitative measures: use only words
26. Quantitative measures use numbers with units In chem we will sometimes use qualitative measures, but sometimes quantitative ones.
Examples:
27. Quantitative measure:
Mr. Arbuiso is ___________________
28. Qualitative measure:
Mr. Arbuiso is ____________________
29. Error
How far away your measure is from accurate.
What was your “error” in measuring the mass of the teacher?
_______________________________________________________________________
It’s always a positive number (no need for a sign)
30. Error is the difference between your measure and the actual measure
Error = |Measured value – Actual value| (those lines indicate absolute value)
31. Percent Error is much more important in our class.
Percent error is how far off you were from your measured value to the actual value expressed as a percentage, with the +/- sign to indicate if you were over or under in your measuring.
32. Formula:
% Error = Measured value – actual valueactual value
X 100%
or
%E = MV – AVAV X 100% Calculate the
% Error now.
What is your % Error?Let’s talk about your answers now.
33. Quick, measure with your eyes, how many inches it is to the top of the door. Write your measurement down.
The actual height is _________”.
Do your Error and %E NOW.
Write the formulas!
34. Standard Units in our class are:
Length: METER, also millimeter, centimeter
Volume: LITER and MILLILITER
Mass: GRAM, and kilogram and milligram
Density: GRAMS/CENTIMETER CUBED or GRAMS PER MILLILETER
Temperature: KELVIN and CENTIGRADE (AKA celcius)
Time: SECONDS
Hand in your student data form now. Put everything, EVERYTHING, into the inbox.Do not hand me stuff - put it into the inbox (unless it is money or chocolate chip cookies)
Measurement Class 2
35. OB: To determine what density is and how it’s measured; what are
the two temperature scales in chemistry and how to convert one to another.
Some background info…
36. MASS: The amount of “stuff” in something
37. VOLUME: The amount of space stuff takes up
38. WEIGHT: The affect of GRAVITY on a mass
39. Mass is a ______________________________
40. Weight ___________ depending upon __________________
41. Density is the mathematical relationship between _____ + ______
42. The formula you to learn is:
Some background info…
MASS: The amount of “stuff” in something
VOLUME: The amount of space stuff takes up
WEIGHT: The affect of GRAVITY on a mass
Mass is a CONSTANT
Weight VARIES depending upon STRENGTH OF GRAVITY (what planet you’re on)
Density is the mathematical relationship between MASS + VOLUME
The formula to learn is: D = mV
Units for density are most often:
43. __________________________ _________
or
44. __________________________ _________
45. __________= _____________ 46. There is NO SUCH THING as an ______
If you don’t GET That, RAISE YOUR HAND AND ASK!
Units for density are most often:
43. grams/centimeter cubed g/cm3
or
44. grams/milliliter g/mL
45. 1 cm3 = 1 mL, 46. There is NO SUCH THING as an mL3
If you don’t GET That, RAISE YOUR HAND AND ASK!
47. A cube or metal has a mass of 4506 grams and it is 10.0 cm per side. (V = s x s x s)Calculate the density of this metal.(you must, must write the formula for each problem!)
47. A cube or metal has a mass of 4506 grams and it is 10.0 cm per side. (V = s x s x s)Calculate the density of this metal.(you must, must write the formula for each problem!)
D = mV = 4506 g
1000 cm3
D = 4.506 g/cm3
48. What metal is it? (how could you know this?)
You could have memorized the density tables from a chem book, or you could just look it up!
It’s titanium, Ti.
49. FIVE pennies together have a mass of 14.5 grams. Their total volume is 1.75 cm3. Calculate the density of the pennies.
49. FIVE pennies together have a mass of 14.5 grams. Their total volume is 1.75 cm3. Calculate the density of the pennies.
D = mV = 14.5 g
1.75 cm3
D = 8.29 g/cm3
50. Assuming the pennies are made up of pure copper, what is your % Error?
%E = MV – AVAV
%E = MV – AVAV
=
%E = -7.48% 3SF
8.29 – 8.96 g/cm3
8.96 g/cm3
51. Is your measured value for density UNDER or OVER the actual measurement for the density of copper? How would you KNOW?
51. Is your measured value for density UNDER or OVER the actual measurement for the density of copper? How would you KNOW?
A Negative percent error means YOUR measure is under the actual measurement.
-7.48% means it was close, (~ 8%) but it was not perfect.
It’s like getting about a 92% correct on a quiz.
52. A bar of metal is 27.73 g and has volume of 4.70 cm3. Is it gold?
= 27.73 g4.70 cm3D = m
VD = 5.90 g.cm3 (3SF!)
Is that the density of gold?Check NOW! No guessing.
Temperature We will not use Fahrenheit (normal for you) temperature in chemistry class.
53. We will use _______________ AKA _____________________
54. As well as ________________________
55. Fill in the chart carefully.
Temperature We will not use Fahrenheit (normal for you) temperature in science class.
We will use Centigrade AKA Celsius
As well as KELVIN
Water boils
Water freezes
Absolute Zero
F C K212°F 100°C 373K
32°F 0°C 273K
O K-273 C
56. Converting Kelvin to Centigrade Formula:
____________57. Calculate room temperature in Kelvin. It’s 26.0°C today. (write the formula to calculate this)
57. Calculate room temperature in Kelvin. It’s 26.0°C today. (write the formula to calculate this)
K = C + 273
K = 26.0 + 273 = 299 K
NOT DEGREES, it’s just Kelvins!
3 SF!
Measurement Class 3
58. OB: defining and understanding significant figures in measuring and in math equations.
Handout: The Significance of Significant Figures.
Significant figures are the numbers in our math that are important enough to count. They have real, or significant, value to the measurement.
We will measure so many things in chemistry, and we’ll use so many formulas, we need to learn how to deal with the numbers. The rules to significant figures is how we’ll do so.
Officially, significant figures is defined this way:59. In a measurement, all numbers you know that you measured properly, plus one more estimated place, are significant.
You want to be sure that your measurements are as correct as possible. You never want to round away how exact you can be. You also are not permitted to be magically more exact than your tool will let you.
For instance, 6 grams is not really the same as 6.0 grams, or 6.00 grams, or 6.000 grams.
The are all measured to different levels of exactness.
If we are going to measure the temperature in this room right now, with our centigrade thermometer, let’s look at the tool now. 60. What temperature is it?
This tool indicates temperature in degrees centigrade. Whole degrees.
With tools that we read with our eyes, like a thermometer, or a ruler, we measure to the closest measure, then estimate out ONE more place. Our eyes can estimate one place, but not two or three more decimal points.
You can’t be “more accurate” than your tool let’s you. You should never give up how exact you can be, (don’t just say it’s 20 degrees centigrade, estimate to the tenth of a degree.
61. ____________________________
Let’s look over these rules on the back of this handout and see if we can’t figure out what this is all about.
For any measures:Rule 1. Any digit 1-9 is going to be significant
(it’s important and we need to keep track of how many SF we have).62. How many significant figures in these temperatures? Which is most/least exact?
23°C 23.1°C 23.39°C
For any measures:1. Any digit 1-9 is going to be significant (it’s important and we need to keep track of how many SF we have).
62. How many significant figures in these temperatures? Which is most/least exact?
23°C 23.1°C 23.39°C
2 SF 3 SF 4 SFLeast exact Most exact
RULE 2. If there’s a ZERO digit between significant figures, that is significant too.
(it’s not just a placeholder)
63. How many SF are in these measures?
101 grams 4509 joules 20,445,567 kilocalories
110 grams 4590 joules 21,445, 567 kilocalories
20,456,056 seconds
RULE 2. If there’s a ZERO digit between significant figures, that is significant too.
(it’s not just a placeholder)
63. How many SF are in these measures?
101 grams 4509 joules 20,445,567 kilocalories
110 grams 4590 joules 21,445, 567 kilocalories
20,456,056 seconds
3 SF 4 SF 8 SF
2 SF 3 SF 8 SF
8 SF
Rule 3. Zeros before SF are not significant (they are placeholders)
64. How many SF in these measures?
0.0054 kilograms _________
0.000000000000001 kPa ________
0.565 grams ___________
Rule 3. Zeros before SF are not significant (they are placeholders)
64. How many SF in these measures?
0.0054 kilograms 2SF
0.000000000000001 kPa 1 SF
0.565 grams 3 SF
Rule 4. Zeros with a decimal point or without a decimal point
(the dot counts!)
150 grams has a zero at the end, and this means we are SURE of 1 one hundred, and 5 tens of grams, but not too sure of the rest. This means it has 2 SF
If the measure is 150. grams, that’s different.We are now sure of all three digits. 3 SF
65. What about these measures, how many sig figs?
250 atm _____ 340. grams ______
55,678,900 seconds ________
14,050. cm _______
48. What about these measures, how many sig figs?
250 atm 2 SF 340. grams 3 SF
55,678,900 seconds 6 SF
14,050. cm 5 SF
RULE 5. Zeros at the end of a decimal number are significant, these ARE NOT PLACEHOLDERS, but indicate you measured to that decimal place and found it to contain NO digits.
66. How many SF in these 4 measures?
1.50 grams _______ 2.0 seconds _______
98,754,123.00 g _______
0.0040 days _______
RULE 5. Zeros at the end of a decimal number are significant, these ARE NOT PLACEHOLDERS, but indicate you measured to that decimal place and found it to contain NO digits.
66. How many SF in these 4 measures?
1.50 grams 3 SF 2.0 seconds 2 SF
98,754,123.00 g 10 SF
0.0040 days 2 SF
RULE 6 - Unlimited Significant Figures Unlimited SF will be important whenever we use EQUALITIES, especially when converting from one unit to another.
67. For example, if we measured 1.5 pounds of butter
and needed to convert it to grams, we’d use this EQUALITY or conversion factor: 1 pound = 454 grams
The calculator answer would be 681 g. This is NOT correct. Our equality has UNLIMITED SF, but our original measure does not, it has 2 SF. Our answer is limited to the LEAST amount of SF in the math.
That’s because
1 pound = 454 grams
Means
1.0 pounds = 454.0 grams
Or
68. 1.00000… pounds = 454.000000… grams
(to the nth degree)That last zero on the end would be
significant, and all the zeros in between would be too, so equalities never “limit” SF.
69. (copy all) In a math equations, the answers must not gain or lose SF. You can’t get MORE EXACT because you multiply or divide, nor should you round away how well you have measured.
70. If you measure your room to be 7.7 meters X 5.4 m, you’ll need a rug of 41.58 m2
Not really.
If you only measure to 2 SF because that’s the limit of your tool, your answer can only have 2 SF. Round the 41.58 m2 to 42 m2 to be correct.
Last rule…
When using scientific notation, only the front part (the coefficient) has SF.
71. How many SF in this measure?
6.02 x 1023 atoms has ___________ SF
Last rule…
When using scientific notation, only the front part (the coefficient) has SF.
71. How many SF n this measure?
6.02 x 1023 atoms has
3 SF, just the 6.02 part counts
Practice (talk together)
72. How many SF in these measures?
123 m _____ 40.506 cm _____
0.345 g _____ 30.0 seconds _____
22 Liters _____ 22.4 liters _____
0.07080 kg ______ 9.7 x 107 years ______
9.70 x 107 years _____
Practice (talk together)
72. How many SF in these measures?
123 m 3 SF 40.506 cm 5 SF
0.345 g 3 SF 30.0 seconds 3 SF
22 Liters 2 SF 22.4 liters 3 SF
0.07080 kg 4 SF 9.7 x 107 years 2 SF
9.70 x 107 years 3 SF
Density is the relationship between mass and volume of a substance. (how much stuff divided by how much space it takes).
The formula is d=m/v
73. If your unknown metal has mass of 11.46 grams and volume of 1.15 cm3, what is the density?
Density is the relationship between mass and volume of a substance. (how much stuff divided by how much space it takes).
The formula is d=m/v
73. If your unknown metal has mass of 11.46 grams and volume of 1.15 cm3, what is the density?
D = massvolume
Density is the relationship between mass and volume of a substance. (how much stuff divided by how much space it takes).
The formula is d=m/v
73. If your unknown metal has mass of 11.46 grams and volume of 1.15 cm3, what is the density?
D = 11.46 g 1.15 cm3
= 9.9652173 g/cm3 ???
Round to only 3 SF!!! 9.97 g/cm3
Density is the relationship between mass and volume of a substance. (how much stuff divided by how much space it takes).
The formula is d = m/v
74. If your unknown metal has mass of 35.46 g + volume of 7.75 cm3, what is the density?
Density is the relationship between mass and volume of a substance. (how much stuff divided by how much space it takes).
The formula is d = m/v
74. If your unknown metal has mass of 35.46 g + volume of 7.75 cm3, what is the density?
D = massvolume
35.46 g7.75 cm3 = 4.57548387 g/cm3
Measurement Class 4
75.OB: Learning the rules and operations of unit conversion math, AKA DIMENSIONAL ANALYSIS
In our lives, and in our studies, we will have to convert our math units from one form to another all the time.Each time you put on your two sneakers in the morning, or your pair of sneakers, you put on the same number of sneakers, but you think it, or say it differently.
76. 2 Sneakers = 1 pair of sneakers
Same thing, right?
No matter if you are playing 52-Pickup or watching a magician, you know that there are 52 cards in the deck of cards. A deck of cards has 52 cards.
77. A deck of cards EQUALS 52 cards.
If your brother ripped the ace of diamonds in half during a minor fit of insanity, you no longer have a deck of cards (although if he’s under eight years old he might not notice).
=
78. If I said how many cards are in 2 decks of cards, or how many shoes are in three pairs of shoes, could you tell me? (104 and 6)
To figure these problems out, you would probably just “do it in your head”, but in fact you are doing dimensional analysis computations.
3 pairs of shoes1 X 2 shoes
1 pair of shoes
= 6 shoesThis is how your “mind” converted from pairs to shoes in units.You didn’t even realize (probably) that 2 shoes = 1 pair of shoes is called an Equality, which can be changed into 2 different CONVERSION FACTORS.
• Conversion factors are used to convert one unit to another.
• All conversion factor numerators must = their denominators.
• They MUST have units top and bottom. MUST.
• They will always equal “1” - right side up or upside down.
Every equality can make 2 different conversion factors, and conversion factors equal 1.
12 inches = 1 foot
12 inches1 foot
1 foot12 inches=
An Equality
TwoConversion
FactorsFrom one equality
79. List these
80.
81. Let’s convert your teacher’s mass (________ pounds) into ounces.
Do you know of an equality with pounds & ounces? 1 pound = 16 ounces
81. Let’s convert your teacher’s mass (________ pounds) into ounces.
Do you know of an equality with pounds & ounces.
___ pounds1
X 16 ounces1 pound = ounces
_____ ounces. WHOA! What about SF? How many SF in the math?
How many SF are supposed to be in the answer? What’s the real answer?
_____________ ounces has 2 SF, which is as close as we can measure.
Let’s try a few one step unit conversion problems in a row. Set it up correctly, with our “starting point” over 1, use units, cancel units, talk to each other and check to see if your neighbor has the same answer as you do.
82. Convert 1.2 kilograms into grams (1 kg = 1000 g).
83. Convert 56,750 mL into liters (l L = 1000 mL).
82. Convert 1.2 kilograms into grams (1 kg = 1000 g).
83. Convert 56,750 mL into liters (l L = 1000 mL).
1.2 kg1 X 1000 g
1 kg = 1200 g
56,750 mL1 X 1 L
1000 mL = 56.75 L
Starting point ◊ watch units ◊ watch SF ◊ BANG!
Multiple step unit conversions…You can sometimes get a problem that you can’t simply convert from one unit to another because you don’t know a conversion factor. But you know other ones, so you can go in steps.
84. Convert your age (you are 15.4 years old right now) into minutes.
How many minutes are in one year? There is an answer to that, and if you know it, you can make this a one step conversion problem.
Since you don’t let’s think.
All conversion factors must equal 1.If you multiply 15.4 x a conversion factor = 15.4
If you multiply 15.4 x a conversion factor x another one = 15.4
You can multiply any number by 1 as many times as you like, it’s ok.
84. Convert 15.4 years into minutes.
15.4 yr1
365 days1 yr
24 hours1 day
60 minutes1 hour
X X X =
15.4 yr1
365 days1 yr
24 hours1 day
60 minutes1 hour
X X X =
Be sure to see how you started OVER 1, and ALL of the units cancel, and the last unit left (minutes) is the one that the answer needs to have!
Do the math, and consider your ANSWER’S SF BEFORE you multiply.
How many SF does your answer NEED to have?
8,094,240 min. with just 3 SF: 8,090,000 min.
85. Convert the 400. meter race into yards so the football players can easily compare that length to their field. 1 inch = 2.54 centimeters
85. Convert the 400. meter race into yards so the football players can easily compare that length to their field. 1 inch = 2.54 centimeters
400. m1
100 cm1 m
1 inch2.54 cm
1 yard36 inches
X X X =
400. m1
100 cm1 m
1 inch2.54 cm
1 yard36 inches
X X X =
How many SF in the answer?! Do the math across the top and write your answer, then CLEAR your calculators. Do the math across the bottom, write your answer, then clear again. Then do the division.
40,00091.44
= 437.445319 changes to 437 yards with 3 SF
86. I live in a make believe world (sometimes) and in my world there are special magical ways that will allow me to convert from unusual units to even more unusual units. Sometimes I bring silly problems back to Earth, just to help my students think abstractly. As long as you have equalities, you can make conversion factors. Ergo, you can convert units easily.
A YOWZA is what a student yells when she earns an all correct on her quiz.1 Yowza feels the same as 3.4 hoo-hoo’s1 hoo-hoo is the same as hollaring 8.2 ka-ching’s1 ka-ching is equal to 2.3 hmmmm’sIt takes 5.9 hmmmm’s to match up with 1.6 unh’s.
So, tell me quick! How many unh’s are the same as 7.00 Yowza’s?
(units are units, and they are there just to be crossed out)
Watch your starting point, and how many SF in your answer?
Homework Tonight: Measurement HW _____
7.00 Y1
3.4 Hoo1 Y
8.2 ka-ch1 Hoo
2.3 hmm1 ka-ch
1.6 unh5.9 hmm
=X X X X
Set it up, watch the unit placement, cancel the units out, is your LAST UNIT the one that you need in the answer?
Do the math across the top, hit equal and write that down.Do the same on the bottom.
Divide and check SF.
718.18885.9
= 121.7269… with 3 SF rounds to 122 unh’s!
Do your homework tonight, I will collect it tomorrow.
87. OB: Scientific Notation for fun and personal enjoyment
You must start with a calculator in hand. Do the math in the proper order and
you’ll always be right!
Measurement Class #5: Scientific Notation
Express the following as Scientific Notation:
88. 17,000,000,000 ants
89. 6,374,000 meters
90. 0.034 gram
91. 0.000 000 000 154 meters (the radius of a carbon atom
92. 0.000 008 m (the diameter of a human hair)
Express the following as Scientific Notation:
88. 17,000,000,000 ants 1.7 x 1010 ants
89. 6,374,000 meters 6.374 x 106 m
90. 0.034 gram 3.4 x 10-2 g
91. 0.000 000 000 154 meters (the radius of a carbon atom 1.54 x 10-10 m
92. 0.000 008 m (the diameter of a human hair) 8 x 10-6 m
93. Scientific notation rule: the coefficient shall always be more than one, less than ten
For example, THESE ARE ALL EQUIVLENT, BUT…
60,500 = 605 x 102
60,500 = 60.5 x 103
60,500 = 6.05 x 104
60,500 = 0.605 x 105
94.
Convert 36.8 kilograms into ounces, answer to be given in scientific notation.(hints: 454 g = 1 pound = 16 ounces) (1kg = 1000 grams) Round to correct SF.
94.
Convert 36.8 kilograms into ounces, answer to be given in scientific notation.(hints: 454 g = 1 pound = 16 ounces)
36.8 kg1
x1000 g
1 kg1 p
454 g16 oz1 p
xx =588 800
454 1296.9163 oz=
1.30 x 103 oz
MAKE SURE YOU SEE how the UNITS CANCEL OUT
95.
Convert 300. seconds into years, answer as scientific notation(hint: your answer will be a small fraction of years, your exponent must be negative)
95.
Convert 300. seconds into years, answer as scientific notation
(hint: your answer will be a small fraction of years, your exponent must be negative)
300. sec1
x1 min60 sec
1 HR60 min
1 day24 HR
xx
= 0.00000950 years = 9.50 x 10-6 years
30.031536000
=x1 year
365 day
MAKE SURE YOU SEE how the UNITS CANCEL OUT
96. Multiplication rules for scientific notation
Multiply coefficients, add powers of ten, adjust coefficient if necessary. (teapot)
97. (3 x 105)(2 x 102) =
98. 5.0 x 104
X 3.0 x 102
Multiplication rules for scientific notation
Multiply coefficients, add powers of ten, adjust coefficient if necessary. (teapot)
97. (3 x 105)(2 x 102) = 6 x 107
98.
5.0 x 104
X 3.0 x 102
15.0 x 106
1.50 x 107
1.5 x 107 with 2 SF
99. Division Rules for Scientific Notation
Divide coefficients, subtract powers of ten, adjust coefficients (teapot) if necessary.
100.
101.
3.0 x 104
2.0 x 102=
9.0 x 105
3.0 x 103 =
Division Rules for Scientific Notation
Divide coefficients, subtract powers of ten, adjust coefficients (teapot) if necessary.
3.0 x 104
2.0 x 102= 3.0
2.0 X 10(4-2) = 1.5 x 102
9.0 x 105
3.0 x 103= 9.0
3.0 X 10(5-3) = 3.0 x 102
102. Addition rules:
Adjust scientific notation so both terms have the SAME POWERS OF TEN, add or subtract coefficients, then adjust answer if necessary (teapot)
103. 104.
6.5 x 107
+ 2.2 x 107
6.2 x 108
+ 1.5 x 106
Adjust scientific notation so both terms have the SAME POWERS OF TEN, add or subtract coefficients, then adjust answer if necessary (teapot)
103. 104.
6.5 x 107
+ 2.2 x 107
8.7 x 107
6.2 x 108
+ 1.5 x 106
6.2 x 108
+ 0.015 x 108
6.215 x 1086.2 x 108
105. Subtraction rules:
Adjust scientific notation so both terms have the SAME POWERS OF TEN, add or subtract coefficients, then adjust answer if necessary (teapot)
106. 107.
8.5 x 103
- 2.4 x 103
7.1 x 105
- 1.6 x 104
Adjust scientific notation so both terms have the SAME POWERS OF TEN, add or subtract coefficients, then adjust answer if necessary (teapot)
106. 107.
8.5 x 103
- 2.4 x 103
6.1 x 103
7.1 x 105
- 1.6 x 104
7.1 x 105
- 0.16 x 105
6.94 x 1056.9 x 105
8.72 x 1011
+ 1.72 x 1010
4.65 x 1014
- 2.25 x 1015
8.72 x 1011
+ 0.172 x 1011
8.892 x 1011
8.89 x 1011
0.465 x 1015
-2.25 x 1015
-1.785 x 1015
-1.79 x 1015
108.
109.
Take out your reference tables, calculators at the ready. (1.06 Qt = 1 L)
112. Convert 2450 mL into gallons. Show all units (3 SF)
112. Convert 2450 mL into gallons. Show all units (3 SF)
2450 mL1
X 1 Liter1000 mL
X 1.06 Qt1 Liter X 1
gallon4 Qt
=
= 2597/4000 = 0.64925 gallons
= 0.649 gallons with 3 SF
113. How many millimeters are in 1000. yards? Put answer into scientific notation.
1000. yd1
X 36 inch1 yd X 2.54 cm
1 inch X 10 mm1 cm
=
= 914,400 mm = 9.144 x 105 mmWith 4 SF
114. If you have exactly 25.0 Liters of water, how much does that weigh in tons? Hint: write the density of pure water first, then see if it helps you convert things around
If you have exactly 25.0 Liters of water, how much does that weigh in tons?The density of pure water is 1.0g per mLwhich should tell you how much 25.0 liters mass is.
25.0 L1
X 1 pound454 g
X 1 ton2000 p
= 25000/ 908000 = 0.0275 tons
with 3 SF2.75 x 10-2 tons
=1000 mL1 L
1 g1 mLX X
In dimensional analysis, the units are there just to be converted. They don’t “really” even matter. In fact, they can be made up, make believe. As long as you have equalities, you can convert from one unit to another, even if they are fake units.Using fake units is called abstract thinking. You need to be abstract now, not obtuse. OK?
Imagine you are working at a zoo. Different animals have different “values”, which are not real, but come into play when trading other zoos to get new cool animals. Think and get psyched for this one…
You wish you could get a new proboscis monkey for the empty cage at your zoo. You have an abundance of lemurs on hand and hope to trade them away. In a multi- zoo trade, you set it all up.
1 proboscis monkey = 14 zebras8 zebras = 1 giraffe2 giraffes = 1 elephant1 elephant = 27 penguins5 penguins = 1 lemur
115. If this is all true (it is, I promise), how many lemurs will it take to get one proboscis monkey? (don’t sweat SF)Round to the nearest whole lemur!
115.
1 proboscis monkey = 14 zebras8 zebras = 1 giraffe2 giraffes = 1 elephant1 elephant = 27 penguins5 penguins = 1 lemur
115. 1 proboscis monkey = 14 zebras8 zebras = 1 giraffe2 giraffes = 1 elephant1 elephant = 27 penguins5 penguins = 1 lemur
= 378/80 = 4.725 or
5 lemurs are equal to 1 proboscis monkey!
1 P.M.1
X 14 zebra1 P.M.
X 1 giraffe8 zebra
X1 elephant2 giraffes X
27 penguins1 elephant
X1 lemur
5 penguins =
116. You have a special moment and discover a hunk of metal in your yard in the dirt. It’s stamped “pure osmium” and “100.0 grams” as well. It looks pretty new and you even believe this is real. What is the volume of this hunk of metal in cm3? Show a formula and all your work. SF are your initials.
116. You have a special moment and discover a hunk of metal in your yard in the dirt. It’s stamped “pure osmium” and “100.0 grams” as well. It looks pretty new and you even believe this is real. What is the volume of this hunk of metal in cm3? Show a formula and all your work.
SF are your initials.
D = Mv
22.587 g/cm3
1= 100.0 g
v
22.587 g/cm3 (v) = 100.0 g
v = 4.42732… = 4.427 cm3 with 4 SF
117. 1.0 pigs equal 1.6 dogs2.2 dogs is equal to 0.95 cats1.9 cats is equal to 3.1 birds1.0 bird is the same as 11.0 spidersand finally, 3.7 spiders is the same as 8.5 bugsIf this is true, how many bugs make up 1.0 pig? (wow)
Please round (UP) to the nearest whole bug (or yuck!)
1.0 pig1
1.6 dog1.0 pig
0.95 cat2.2 dogs
3.1 birds1.9 cats
11.0 spiders1.0 birds
8.5 bugs3.7 spiders
xx x x x
1.0 x 1.6 x 0.95 x 3.1 x 11.0 x 8.5 = 440.572 = 28.48648649 bugs 1 x 1.0 x 2.2 x 1.9 x 1.0 x 3.7 = 15.466
Rounded to the nearest whole bug, that’s 29 bugs!
117.
Measurement Class 6:REVIEW FOR CELEBRATION OF KNOWLEDGE
Objective: more chemistry math, because you gotta love it!
Get a calculator in your hot little hand, sit with a few smart friends, let’s go…
First, determine how many significant figures are in each of these measurements:
5,600 grams___ 5.600 kilograms___
4.305 mL___ 0.678°C___
0.00065 moles Hg___ 1.400 seconds___
The product of 4.569 grams x 2.0 g/cm3___
First, determine how many significant figures are in each of these measurements:
5,600 grams 2 SF
5.600 kilograms 4 SF
4.305 mL 4 SF
0.678°C 3 SF
0.00065 moles Hg 2 SF
1.400 seconds 4 SF
Product of 4.569 grams x 2.0 g/cm3 2 SF
Do the drills for SF if you need to.
(you do)
In each set of temperatures, decide which is the coldest, which is the hottest.
10 Kelvin10 centigrade10 Fahrenheit
280 K32°F6°C
Convert -15.0°C into K
Convert350 K to C
In each set of temperatures, decide which is the coldest, which is the hottest.
10 Kelvin COLDEST10 centigrade HOTTEST10 Fahrenheit
280 K HOTTEST32°F COLDEST6°C
Convert -15.0°C into KK = C + 273K = (-15) + 273K = 258 K
Convert 350 K to CK = C + 273350 K = C + 273-273 = -27377° C = C
Two quick (and easy) one step dimensional analysis problems to solve…
Convert 125 grams into kilograms
Convert 34.75 liters into mL
Two quick (and easy) one step dimensional analysis problems to solve…
Convert 125 grams into kilograms
Convert 34.75 liters into mL
125 g1
x 1 kg1000 g
= 0.125 kg with 3 SF
34.75 L1
x 1000 mL1 L
= 34,750 mL with 4 SF
In the funky world that your teacher resides, there are some weird equalities. Given a short list of them, you should be able to solve a funky problem like this…
How many light switches will equal one house?
Equalities
1.0 house = 8.0 rooms 2.0 rooms = 3.0 windows
1.0 windows = 2.0 lights 3.0 lights = 4.0 light switches
In the funky world that your teacher resides, there are some weird equalities. Given a short list of them, you should be able to solve a funky problem like this…
How many light switches will equal one house?
Equalities
1.0 house = 8.0 rooms 2.0 rooms = 3.0 windows
1.0 windows = 2.0 lights 3.0 lights = 4.0 light switches
1.0 House1
x 8.0 Rooms1.0 House
x 3.0 Windows2.0 Rooms
x 2.0 Lights1.0 Windows
x 4.0 Switches3.0 Lights
=
1926 32 switches
(2 SF)
You measure some pure niobium metal to have a density of 8.00 g/cm3. What is your percent error? (hint, write the formula first)
You measure some pure niobium metal to have a density of 8.00 g/cm3. What is your percent error? (hint, write the formula first)
MV – AVAV
X 100% =% E =
8.00 g/cm3 – 8.570 g/cm3
8.570 g/cm3X 100% =% E =
% E = - 6.65%
Do what the math says to do:
(3.5 x 106)(2.0 x 102) = ____________________________
(8.0 x 108) ÷ (4.0 x 1012) = ___________________________
Do what the math says to do:
(3.3 x 108) + (1.2 x 107) = ___________________________
(5.64 x 105) – (2.33 x 104) = _________________________
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