Chemistry Chapter 3

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10/23/2011

meter- m

kilogram-kg

kelvin-K

seconds-s

Mole-mol

1000x unit
(1000m=1 km)

10dm= 1 meter
10

100cm= 1 meter
100

1000mm= 1 meter

micro

1 x 10^6 um= 1 meter

nano

1 x 10 ^9= 1 meter

pico

1 x 10 ^12 pm= 1 meter

Conversion factors

fractions that represent the same unit (where the numerator and the denominator are equal to each other)
ex. 100 cents/1 dollar

How are conversion factors used?

used to solve any kind of problem

International System of Units

the revised version of the metric system, adopted by international agreement in 1960
The five SI base units commonly used by chemists are the meter, the kilogram, the kelvin, the second, and the mole.

Weight

a force that measures the pull on a given mass by gravity. It is a measure of force, it's different from mass, which is a measure of the quantity of matter.

Kelvin Scale

the freezing point of water is 273.15 kelvins (K), and the boiling point is 373.15 K. Notice that with the Kelvin scale, the degree sign is not used.
The zero point on the Kelvinscale, 0 K, or absolute zero, is equal to −273.15°C.

Energy

the capacity to do work or to produce heat

joule (J)

the SI unit of energy. It is named after the English physicist James Prescott Joule

calorie (cal)

One of these is the quantity of heat that raises the temperature of 1 g of pure water by 1°C

Dimensional Analysis

a way to analyze and solve problems using the units, or dimensions, of the measurements. The best way to explain this problem-solving technique is to use it to solve an everyday situation.

Density

the ratio of the mass of an object to its volume.
densisty= mass/volume

Measurement

a quantity that has both a number and a unit, fundamental to the experimental sciences

scientific notation

a given number is written as the product if two numbers: a coefficent and 10 raised to a power

Accuracy

a measure of how close a measurement comes to the actual or true value of whatever is measured

Precision

a measure of how close a series of measurments are to one another

To evaluate accuracy...

measured value compared to the correct value

To evaluate precision...

compare the values of two or more repeated measurments

Accepted Value

the correct value based on reliable references

Experimental Value

the value measured in the lab

Error

the difference between the experimental value and the accepted value
Error= experimental value - accepted value

Percent Error

The absolute value of the error divided by the accepted value, multiplied by 100
% error= |error| / accepted value x 100

K= C + 273

C= K - 273

Example: