Summer Chemistry Honors: Chapter 3 (Numbers)
Exact or measured? a) 1 yard = 3 feet b) The diameter of a red blood cell is 6 x 10^-4 cm c) There are 6 hats on the shelf d) Gold melts at 1064C
a) exact; this is a defined relationship b) measured; a measuring tool is used to determine length; c) exact; the number of hats is obtained by counting d) A measuring tool is required
What are the names of these units and their symbols: a) Mass b) Length c) Time d) Temperature
a) grams or kilograms (kg or g) b) meter or centimeters (m) c) second (s) d) Kelvin (K)
The ______ ______ is the correct value based on reliable references.
accepted value
In carrying out an ______ or ______, the answer cannot have more digits after the decimal point than either of the original numbers.
addition; subtraction
When the original number is less than 1, the exponent is _______. a) positive b) negative
b
Exact relations and predefined values are a) measured b) not measured
b; 1 foot = 12 inches 1 meter = 100 cm
Zeros at the ______ of a number are not significant; they act only to locate the decimal point. Thus, 0.0834 has _____ significant figures, and 0.02907 ml has ____.
beginning; three; four
For conversions within the metric system, each "step" is 1 _____ _____ to the right or left.
decimal place
Zeros at the _____ of a number and _____ the decimal point are significant. It is assumed that these zeros would not be shown unless they were significant. 138.200 m has ___ significant figures. If the value were known to only four significant figures, we would write 138.2 m.
end; after; six
Zeros at the ____ of a number and _____ an implied decimal point ARE NOT significant (if they were, a decimal point would be added.) 3,000 has only ___ significant digit, but 3000. has ____.
end; before; 1; 4
Measured number = they are measured with a measuring device so these numbers have _______.
error
The difference between the experimental value and the accepted value is called the ______.
error
An _____ ______ is obtained when you count objects or use a defined relationship.
exact number
The ______ _____ is the value measured in the lab.
experimental value
Zeros in the ______ of a number are like any other digit; they are always significant. Thus, 94.072 g has ____ significant figures.
five
Exact numbers are ______ important (if you count 3 monkeys, it is EXACTLY 3)
infinitely
What are the three prefixes that we will use the most?
kilo, centi, milli
From each prefix every "step" is either: 10 times ______ or 10 times _______
larger; smaller
Every experimental measurement has a degree of ______.
uncertainty
Express 1.8 x 10^-4 in decimal notation.
.00018 (original number is less than one so exponent is negative)
What is the percent error if the experimental value is 99.1C and the accepted value is 100.0C?
.9%
How would you write 210,000,000,000,000, 000, 000, 000 (22 zeros) in scientific notation?
2.1 x 10^23
For every 1 inch you have _____ cm. For every 1 inch you have _____ mm.
2.5; 25
Write 28750.9 in scientific notation.
2.87509 x 10^4 (original number is greater than one so exponent is positive)
What is the answer to the following? 278 mi/11.70 gal
23.8 mi/gal
What is the answer to the following? 3.18 L + .01315 L =
3.19 L
True or False? When you use your calculator your answer can only be as accurate as your best measurement.
False When you use your calculator your answer can only be as accurate as your worst measurement.
True or False? If a calculation has several steps, it is best to round off in the beginning.
False; If a calculation has several steps, it is best to round off at the end.
What are the two types of observations? Give an example of each.
Qualitative: "The substance is a yellow solid." Quantitative: "The substance weighs 4.3 grams."
What is the objective of scientific notation?
The objective is to show how very small or very large numbers can be expressed as the product of a number between 1 and 10.
True or False? When using our calculators we must determine the correct answer; our calculators are mindless drones and don't know the correct answer.
True
True or false? To know if you are accurate, you have to know what the right answer was supposed to be.
True
What are the two widely used systems of units?
the English system and the metric system
Write (2.8 x 10^3)(5.1 x 10^-7) in scientific notation.
1.428 x 10^-3
1 centimer = ____ millimeters
10
Centimeters are ____ times larger than millimeters
10
When rounding numbers, if the first digit you remove is ___ or less, drop it and all following digits. 2.4271 becomes 2.4 when rounded off to two significant figures because the first dropped digit (a 2) is 4 or less.
4
4.58 x 10^6 is typed on a calculator ____________.
4.85 EE 6
When rounding numbers, if the first digit removed is ___ or greater, round up by adding 1 to the last digit kept. 4.5832 is 4.6 when rounded off to 2 significant figures since the first dropped eight (an 8) if 5 or greater.
5
Express .0000000902 in scientific notation.
9.02 x 10^-8
______ is a measure of how close a measurement comes to the actual or true value of whatever is measured.
Accuracy
210,000,000,000,000, 000, 000, 000 (22 zeros) This number is written in ______ notation.
Decimal
On the graphing calculator, scientific notation is done with the ____ or "___" button.
EXP; EE
What is the formula to find the error?
Error = experimental value - accepted value
What are the 2 different types of numbers?
Exact; Measured
What trick can you use to remember the order of the units in the metric system?
King Henry Died Basically Drinking Chocolate Milk (kilo) (hecto) (deka) (l, g, m) (deci) (centi) (milli)
What is the formula to find the percent error?
Percent error = |experimental value - accepted value|/accepted value x 100
______ is a measure of how close a series of measurements are to one another. Are you getting the same answer each time?
Precision
When the original number is more than one, the exponent is _______. a) positive b) negative
a
What are the answers to the following? a) .56 + .153 = .713 b) 82000 + 5.32 = 82005.32 c) 10.0 - 9.8742 = .12580 d) 10 - 9.8742 = .12580
a) .71 b) 82005 c) .1 d) 0
Make the following into a 3 Sig Fig number. a) 1.5587 b) .0037421 c) 1367 d) 128,522 e) 1.6683 x 10^6
a) 1.56 b) .00374 c) 1370 d) 129,000 e) 1.67 x 10^6
What are the answers to the following? a) 8.52 + 4.1586 x 18.73 + 153.2 b) (8.52 + 4.1586) x (18.73 + 153.2)
a) 239.6 b) 2180. NOTE: Remember to add decimal point since you need 4 significant figures
What are the answers to the following? a) 32.27 x 1.54 = 49.6958 b) 3.68 / .07925 = 46.4343312 c) 1.750 x .0342000 = .05985 d) 3.2650 x 10^6 x 4.858 = 1.586137 x 10^7 e) 6.022 x 10^23 x 1.661 x 10^-24 = 1.000000
a) 49.7 b) 46.4 c) .05985 d) 1.586 x 10^7 e) 1.000
Make the following into a 4 Sig Fig number. a) 4965.03 b) 780,582 c) 1999.5
a) 4965 b) 780,600 c) 2000. Note: You need a 4 sig fig so you add a decimal (.) at the end
How many significant figures does each have? a) 45.8736 b) .000239 c) .00023900 d) 48000. e) 48000 f) 3.982 x 10^6 g) 1.00040
a) 6 b) 3 c) 5 d) 5 e) 2 f) 4 g) 6
What are the three basic units?
meter, gram, liter
What is the preferred system of choice when referring to units? What are these units called?
metric system; SI units
In carrying out a ______ or _______, the answer cannot have more significant figures than either of the original numbers.
multiplication; divison
Measurements always consist of two parts: a _____ and a _____.
number; unit
All but ____ of the significant figures are known with certainty. The last significant figure is only the best possible estimate.
one
When you estimate a measurement from a measuring device you estimate __ unit past the unit the measuring device goes to.
one; For example, if a ruler measures ml like 1, 2, 3, 4 and the object stops between the two and the three, you would write 2.5 ml.
The _______ ______ is the absolute value of the error divided by the accepted value, multiplied by 100.
percent error
What are the prefixes of the SI units based on?
powers of 10
To indicate the ______ of a measurement, the value recorded should use all the digits known with certainty plus the last estimated digit.
precision
When reading a measured value, all nonzero digits should be counted as _______.
significant