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Chem 101: Chapter 1
Keys to the Study of Chemistry
10
Chemistry
Undergraduate 1
09/30/2009

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Cards

Term

1) Define: Precision

2) What kind of error do precise measurements have?

Definition

1) refers to reproductablilty or how close measurements are to one another

2) Precise measurements have low random error

Term

1) Define: Accuracy

2) What tipe of error do accurate measurements have?

Definition

1) refers to how close a measurement is to the actual value

2) low systematic error and generally low random error

Term

1) Define: Systematic Error

2) How can this be avoided?

Definition

1) produces values that are either all higher or all lower than the actual value

2) can be avoided by calibrating measurement devices

Term

1) Define: Random Error

2) How can it be avoided?

Definition

1) produces values that are both higher and lower than the actual value

2) it can't be completely avoided but it varies in size

Term
General procedures for calculating Significant Figures
Definition

1) make sure there is a decimal point

2) move from left to right until you hit the first non-zero

3) count that didgit and every digit to its right

*note: if right most digit is a zero and there is no decimal point, it is not significant*

Term

Significant Figures:

Multiplication and Division Rules

Definition
round to the smallest number of significant figures
Term

Significant Figures:

Addition and Subtraction

Definition
round to the least number of decimal places
Term

Rounding rules when ending in 5

ex. round 46.35 and 102.25 to the tenths place

Definition

"round to the evens"

if # before 5 is even, round down

if # before 5 is odd, round up

ex. 46.4 and 102.2

Term
In a multi-step problem, when do you round?
Definition
The very end, even when considering significant figures
Term
Do exact numbers count for sig figs?
Definition
NO!!! only consider sig figs with calculated values
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