Chapter 1.
What is Chemistry?
R=Chemistry is too universal and dynamically-changing a subject to be confined to a fixed definition; it might be better to think of chemistry more as a point of view that places its major focus on the structure and properties of substances— particular kinds of matter— and especially on the changes that they undergo.
| atto- | a | 10-18 * | -- |
| femto- | f | 10-15 * | -- |
| pico- | p | 10-12 * | -- |
| nano- | n | 10-9 * | -- |
| micro- | m | 10-6 * | -- |
| milli- | m | 10-3 * | -- |
| centi- | c | 10-2 * | -- |
| deci- | d | 10-1 * | -- |
| (none) | -- | 100 | 20 |
| deka- | D | 101 * | -- |
| hecto- | h | 102 * | -- |
| kilo- | k or K ** | 103 | 210 |
| mega- | M | 106 | 220 |
| giga- | G | 109 | 230 |
| tera- | T | 1012 | 240 |
| peta- | P | 1015 | 250 |
| exa- | E | 1018 * | 260 |
The Significant Figures of a number are those digits that carry meaning contributing to its precision (see entry for Accuracy and precision). This includes all digits except:
leading and trailing zeros where they serve merely as placeholders to indicate the scale of the number.
They have several rules for the zeros:
leading and trailing zeros where they serve merely as placeholders to indicate the scale of the number.
They have several rules for the zeros:
- All non-zero digits are considered significant. For example, 91 has two significant figures (9 and 1), while 123.45 has five significant figures (1, 2, 3, 4 and 5).
- Zeros appearing anywhere between two non-zero digits are significant. Example: 101.12 has five significant figures: 1, 0, 1, 1 and 2.
- Leading zeros are not significant. For example, 0.00052 has two significant figures: 5 and 2.
- Trailing zeros in a number containing a decimal point are significant. For example, 12.2300 have six significant figures: 1, 2, 2, 3, 0 and 0. The number 0.000122300 still has only six significant figures (the zeros before the 1 are not significant). In addition, 120.00 has five significant figures. This convention clarifies the precision of such numbers; for example, if a result accurate to four decimal places is given as 12.23 then it might be understood that only two decimal places of accuracy are available. Stating the result as 12.2300 makes clear that it is accurate to four decimal places.
They have to Rounded too
Start with the leftmost non-zero digit (e.g. the '1' in 1200, or the '2' in 0.0256).
- Keep n digits. Replace the rest with zeros.
- Round up by one if appropriate. For example, if rounding 0.039 to 1 significant figure, the result would be 0.04. There are several different rules for handling borderline cases — see rounding for more details.
1. A)1 sf 1
b) 2 sf 10
c) 4 sf 523.0
d) 2 sf 0.013
e) 1 sf 0.0000000003
f)1 sf 7
b) 2 sf 10
c) 4 sf 523.0
d) 2 sf 0.013
e) 1 sf 0.0000000003
f)1 sf 7
2. A) 3 sf 502
B) 4 sf 10.23
c) 4 sf 0.001234
D) 1 sf 0.0000000000009
e)7 sf 269.03459
F) 1 sf 1x10^3
g) 3 sf 1.23 x10^2
h) 3 sf 9.21
B) 4 sf 10.23
c) 4 sf 0.001234
D) 1 sf 0.0000000000009
e)7 sf 269.03459
F) 1 sf 1x10^3
g) 3 sf 1.23 x10^2
h) 3 sf 9.21
And then we saw Dimensional analysis.
In this case the dimensional analysis is functional when you are resolving numbers that has many rulers like conversion factors.
= 
= 416.66666666666674 m/miThe temperature. The temperature is a physical property that underlies the common notions of hot and cold. Something that feels hotter generally has a higher temperature, though temperature is not a direct measurement of heat. They have many ways to measure in scales…
Kelvin= Mathematically
Celsius= By the building point of water and his freezing point.
Fahrenheit= the building point of alcohol and body temperature
Kelvin= Mathematically
Celsius= By the building point of water and his freezing point.
Fahrenheit= the building point of alcohol and body temperature
These scales have many ways to measure the temperature and have many explications for his way to measure.
C = (68 - 32) * 5/9,
C = 36 * 5/9,
C = 20
20 °C = 68 °F
At what temperature are Celsius and Fahrenheit temperatures equal?
Replace both temperatures with "T" in one of the equations above and just solve for T:
T = T * 9/5 + 32,
-32 + T = T * 9/5,
-32 = T * 4/5,
-40 = T
-40 °C = -40 °F
C = 36 * 5/9,
C = 20
20 °C = 68 °F
At what temperature are Celsius and Fahrenheit temperatures equal?
Replace both temperatures with "T" in one of the equations above and just solve for T:
T = T * 9/5 + 32,
-32 + T = T * 9/5,
-32 = T * 4/5,
-40 = T
-40 °C = -40 °F
