Beykeny University General Chemist Lesson 2
General Chemist
Chapter I Essential Ideas
Measurements
Measurements provide the information that is the basis of most of the hypothesis, theorys and law in chemistry. Every measurements provides three kinds of information .
The size or magnitude of the measurement a number.
A standard of comparison for the measurements a unit.
An indication of the uncertainty of the measurement.
The SI unit of length is the meter(m)
A Meter is about 3 inches longer than 1 yard
The SI unit of mass is the kilogram(kg)
1 kilogram is about 2.2 pounds.
The Relative length is of(m,1 yd,1 cm and 1 in are shown(not actual size)
The SI unit of temperature is the kelvin(k)
The Degree Celsius ('C) is also a load in the SI system.
The SI unit of time is the second(s)
VOLUME
The measure of the amount of space occupied by an object.
The Standard SI unit for volume is the cubs meter.(m^3),which is divided from the SI basis unit of lenght.
Other units for volume are the liter(L) and milliliter(ml)
1 dm^2 = 1 L
DENSITY
The Density of a subs a is the radio of the mass of an sample of the substance to it's volume
The Standard SI unit on the density is the kilogram divided cubs meter(kg/m^3).
Common used density units based on standard matter.
density = mass/volume
Measurement uncertainty accuracy and procession the result of country measurement is an example of an exact number.
The numbers of defined quantities are also exact.
1 ft is exactly 12 in
1 in is exactly 2,54 cm
2 g is exactly 0,001 kg
SIGNIFICANT FIGURES
All the digits measurement including are the last significant figure or significant digits.
SIGNIFICANT FIGURES IN CALCULATE
The follow in examples illustrate the application of this rule in rounding a fifth different numbers to there significant figures.
0,028657
dropped digits seven grater than seven
0,0287
Mathematician Treatments and Measurements Results
A quantity of interest may not be easy to measure directly bu instead must be calculated directly from other directly measured property and approperty mathematical relationship.
The mathematical approach we will be using is num as dimensional analysis.
CONVERSION FACTOR AND DIMENSIONAL RELATIVES
| ____ | * | 1 in 2.54 | = | ? in |
Conversion of Temperature Units
Temperature refers to the hotness and coldness of substance.
Celsius Scale
Water freeze a 0'c
Water boils at 100'c
Fahrenheit Scale
Water Freeze as at 180'F
Celsius Scale
Water freeze a 0'c
Water boils at 100'c
Fahrenheit Scale
Water Freeze as at 180'F
Fahrenheit and Celsius
°F = °C × 1.8 + 32
Kelvin and Celsius
°K = °C + 273.15
The Fahrenheit Celsius and kelvin temperature scalier are compared.
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