Chapter 2 Section 3 Flashcards Preview

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Flashcards in Chapter 2 Section 3 Deck (70):
1

Accuracy

The closeness of measurements to the correct or accepted value of the quantity measured

2

Precision

The closeness of a set of measurements of the same quantity made in the same way

3

Measured values that are accurate are close to the

Accepted value

4

Measured values that are precise are close to

One another but not necessarily close to the accepted value

5

The accuracy of an individual value or if an average experimental value can be compared

Quantitatively with the correct or accepted value by calculating the percentage error

6

Percentage error is calculated by subtracting the

Accepted value from the experimental value, dividing the difference by the accepted value, and then multiplying by 100

7

Percentage error=

Experimental-accepted
----------------------x 100
Accepted

8

In science for a reported measurement to be useful there must be some indication of

It's reliability or uncertainty

9

Percentage error has a negative value of the accepted value is

Greater than the experimental value. The opposite is also true

10

The skill of the measured places

Limits on the reliability of the results

11

Conditions of measurement and the measuring instruments themselves place

Limits on precision

12

When you use a properly calibrated measuring device you can be almost certain of a

Particular number of digits in a reading

13

The hundredths place is somewhat

Uncertain but should not be left out because you have some indication of the values likely range

14

Thus the value would be estimated to the final

Questionable digit, possibly including a plus-or-minus value to express range

15

Measured values are reported in terms of

Significant figures

16

Significant figures in a measurement consist of all the

Digits known with certainty plus one final digit, which is somewhat uncertain or is estimated

17

Term significant does not mean

Certain

18

In any correctly reported measured value the final

Digit is significant but not certain

19

Insignificant numbers are

Never reported

20

The significance of zeros in a number depends on

Their location

21

Zeros appearing between nonzero digits are

Significant

22

Zeros at the end of a number and to the right of a decimal point are

Significant

23

Zeros at the end of a number but to the left of the decimal point

May or may not be significant

24

Zeros appearing in front of all nonzero digits are

Not significant

25

A decimal point placed after zeros indicated that they

Are significant

26

The answers given on a calculator can be

Derived results with more digits than are justified by the measurements

27

Answers have to be

Rounded off to make its degree of certainty match that in the original measurements

28

The extent of rounding required in a given Case depends on whether the numbers are

Being added, subtracted, multiplied, or divided

29

(Rounding rules) greater than 5

Increased by 1

30

(Rounding rules) less than 5

Stays the same

31

(Rounding rules) 5, followed by nonzero digits

Increases by 1

32

(Rounding rules) 5, not followed by nonzero digits, and preceded by an odd digit

Be increased by 1

33

(Rounding rules) 5, not followed by nonzero digits, and preceding significant digit is even

Stay the same

34

When adding or subtracting decimals the answer must have the same number of

Digits to the right of the decimal point as there are in the measurement with the fewest digit to the right of the decimal pt

35

When working with whole numbers the answer should be rounded so that the

Final significant digit is in the same place as the leftmost uncertain digit

36

For multiplication or division the answer can have no more significant figures than are in the

Measurement with the fewest number of significant figures

37

Conversion factors are typically

Exact

38

Because the conversion factor is considered exact the answer would not be

Rounded

39

Most exact conversion factors are

Derived, rather than measured, quantities

40

Counted numbers also product

Conversion factors of unlimited precision

41

In scientific notation numbers are written in the form

M x 10^n, where M is a whole number greater than or equal to one but less than 10 and n is a whole number

42

Wen numbers are written in scientific notation only the

Significant figures are shown

43

Determine M by moving the decimal point in the original number to the

Left/ right so that only one nonzero digit remains to the left of the decimal point

44

Determine n by counting the number of places that you moved the

Decimal point. If you moved it to the left, n is positive. The opposite is also tee

45

Addition and subtraction can be performed only if the by

Values have the same exponent (n factor)

46

If they don't have the same n factor, adjustments must be made to the values so that

Their exponents are equal

47

The exponent of the answer can remain the same or it may then require adjustment if the

M factor of the answer has more than one digit to the left of the decimal point

48

Multiplication the M factors are

Multiplied and the exponents are added algebraically

49

Division the m factors are

Divided and exponent of denominator is subtracted from that of the numerator

50

The first step in solving a quantitiative word problem is to read the problem

Carefully at least twice and to analyze the information

51

Note any important descriptive terms that c

Clarify or add meaning
Identify and list data
Identify the unknown

52

Develop a plan for solving the problem that shows how

Info given is to be used to find the unknown

53

Decide which

Conversion factors
Mathematical formulas
Chemical principles you will need to solve the problem

54

The third step involved substituting

The data and necessary conversion factors into the plan you have developed

55

Computing

Calculate the answer
Cancel units
Round the result to the correct number of significant figures

56

Calculate your answer to determine whether it is reasonable

Check if units are correct
Make an estimate of expected answer and compare with actual result
Check order of magnitude
Ensure that answer has correct number of significant figures

57

Two quantities are directly proportional to each other if

Dividing one by the other gives a constant value

58

When 2 variables, x And y, are directly proportional the relationship. An be expressed as

y ∝ x.

59

y ∝ x.

Y is proportional to x

60

General equation for a directly proportions relationship between two variables

Y
- = k
X

61

K

Proportionally constant

62

Equation expresses that in a direct proportion ratio between 2 variables

Remains constant

63

Directly equation can be rearranged into

Y = kx

64

If 2 variables are directly proportional their graph is

A straight line that passes through the origin

65

Two quantities are inversely proportional to each other if their products are

Constant

66

Equation for inversely proportional equation

y ∝ 1
-
X

67

Equation thing for inversely means

Y is proportional to 1 divided by x

68

Equation can be rewritten as

K = xy

69

In this equation (inversely) if x increases, y must

Decrease by the same factor to keep the product constant

70

Inversely proportional graph produced a

Curve called a hyperbola