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alamo - CHEM 1405028 - Class Notes - Week 2

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Ch. 2 Chemistry and MeasurementsDon't forget about the age old question of What revolution was characterized by the shift from agrarian to industrial economy?

Standard measurements = metric system

Measurement

Metric

SI

length

Meter (m)

meter(m) kilometers(km)

volume

Liter (L)

Cubic meter (m3)

mass

Gram (g)

Kilogram (kg)

temperature

Degree celsius (oC)

Kelvin (k)

time

Scond (s)

Second (s)

We also discuss several other topics like 1.0075^12

1m = 100 cm 1m = 1.09 yd

1m = 39.4 in 2.54 cm = 1 in.If you want to learn more check out What forms around ions when water is dissolving salts?

We also discuss several other topics like Describe the coronary circulation.

Don't forget about the age old question of What significant event led to the The Tenure of Office Act (1867)?

Volume is the space occupied by a substance. The si unit of volume is m3, however, the metric system, volume is based on the liter, which is a tad larger than a quart.

Mass of an object is a measure of the quantity of material. Kilogram (kg) is used for larger masses. gram (g) is used for smaller masses.If you want to learn more check out Is Bernard William persuasive?

Temperature tells us how hot or cold something is. Celsius (oC) & Kelvin (K)

Water freezes at 37° F or 0°C

The Kelvin scale for temperature begins at the lowest possible temp, O K

Time is measured in units, minutes, hours, days, etc we will use seconds (s).

Measured numbers are the numbers obtained when you measure a quantity of something (Significant Figures) all the digits, including estimated digit Sig Fig are used

- to represent the amount of error associated with a measurement
- are all nonzero digits and zeros between digits
- are not zeros that act as placeholders betere digits
- are zeros at the end of a decimal number

Measured number

Number of Significant Figure

50

2

45

2

48 x 102

2

3000

1

3000.

↖Makes a difference

4

Exact Numbers Not measured & do not have a limited number of significant figures, Not used to find the number of sig fig in a calculated answer.

Numbers obtained by counting 8 cookies

Definitions that compare 2 units 6 eggs

Def, of the same measuring system 1qt = 4 cups

1kg = 1000g

Rules for rounding

3.1457 g ↓

3.146 g ↓

3.15 g ↓

Multiplication and Division

24.66 cm x 0.35 cm = 8.631 (calculator display)

= 8.6 cm2 (2 sig fig)

17.04 2.0 = 8.5 cm

Addition and Subtraction

The final answer is written so that it has the same number of decimal places as the measurement with the fewest decimal places.

2.012 65.09

61.09 - 3.0

+ 3.0 62.09

66.102 62.1 correct answer

66.1 correct answer

82.409 mg

+ 22.0 mg

104.409 mg

104.4 mg

Prefixes and Equalities

- A prefix can be placed in front of any unit to increase or decrease its size by some factor of ten. Ex: milli and micro

- milligram (mg)
- microgram (mg)

Kilo = always means 1000

1000 gram = 1 kilogram

1000 seconds = 1 kilosecond

1000 liters = 1 kiloliter

1000 m = 1 km

milli = “one thousandth of”

Prefixes that increase the size of the unit

Peta P 10-1

Tera T 10-2

Giga G

Mega M 106

Kilo K 103