General Flashcards
The English System of Units consists of:
- Length: inch (in), foot (ft), yard (yd), mile (mi)
- Volume: fluid ounce (oz), cup (c), pint (pt), quart (qt), gallon (gal)
- Weight: ounce (oz), pound (lb), ton
- Time: second (s), minute (min), hour (h), day (d), year (y)
English System of Units conversion factors:
- Length:
12 in = 1 ft; 3 ft = 1 yd; 5280 ft = 1 mi; 1760 yd = 1 mi - Volume:
2 c = 1 pt; 2 pt = 1 qt; 32 oz = 1 qt; 4 qt = 1 gal - Weight:
16 oz = 1 lb; 2000 lb = 1 ton - Time:
60 s = 1 min; 60 min = 1 h; 24 h = 1 d; 365 1/4 d = 1 y
Units of the Metric System:
- Length: meter (m)
- Volume: liter (L)
- Mass: gram (g)
Metric System prefixes:
- femto-
- pico-
- nano-
- micro-
- milli-
- centi-
- deci-
- kilo-
- mega-
- giga-
- tera-
Femto-:
Symbol: f
Meaning: 10^-15
Pico-:
Symbol: p
Meaning: 10^-12
Nano-:
Symbol: n
Meaning: 10^-9
Micro-:
Symbol: mu
Meaning: 10^-6
Milli-:
Symbol: m
Meaning: 10^-3
Centi-:
Symbol: c
Meaning: 10^-2
Deci-:
Symbol: d
Meaning: 10^-1
Kilo-:
Symbol: k
Meaning: 10^3
Mega-:
Symbol: M
Meaning: 10^6
Giga-:
Symbol: G
Meaning: 10^9
Tera-:
Symbol: T
Meaning: 10^12
1 mL =
1 cm^3
1 g =
1 mL H20 at 4 C
Mass versus Weight:
Mass is a measure of the amount of matter in an object, so the mass of an object is constant.
Weight is a measure of the force of attraction of the earth acting on an object. The weight of an object is not constant.
The seven base units for the SI system are:
- Length: meter (m)
- Mass: kilogram (kg)
- Time: second (s)
- Temperature: kelvin (K)
- Electric current: ampere (D)
- Amount of substance: mole (mol)
- Luminous intensity: candela (cd)
The common derived SI units used in chemistry are:
- density (kg/m^3)
- electric charge: coulomb (C (A s))
- electric potential: volt (V (J/C))
- energy: joule (J (kg-m^2/s^2))
- force: newton (N (kg-m/s^2))
- frequency: hertz (Hz (s^-1))
- pressure: pascal (Pa (N/m^2))
- velocity (speed): meters per second (m/s)
- volume: cubic meter (m^3)
The Non-SI units in common use:
- Volume: liter (L (10^-3 m^3)
- Length: angstrom (D (0.1 nm))
- Pressure: atmosphere (atm (101.325 kPa))
torr (mmHg (133.32 Pa)) - Energy: electron volt (eV (1.601 x 10^-19 J))
- Temperature: degree Celsius (EC (K - 273.15))
- Concentration: molarity (M (mol/L))
Unit conversions for length:
1 m = 1.094 yd
1 yd = 0.9144 m
Unit conversions for volume:
1 L = 1.057 qt
1 qt = 0.9464 L
Unit conversions for mass:
1 g = 0.002205 lb
1 lb = 453.6 g
1 in =
2.54 cm
Systematic error:
can be caused by an imperfection in the equipment being used or from mistakes the individual makes while taking the measurement. A balance incorrectly calibrated would result in a systematic error. Consistently reading the buret wrong would result in a systematic error.
Random errors:
often result from limitations in the equipment or techniques used to make a measurement. Suppose, for example, that you wanted to collect 25 mL of a solution. You could use a beaker, a graduated cylinder, or a buret. Volume measurements made with a 50-mL beaker are accurate to within 5 mL. In other words, you would be as likely to obtain 20 mL of solution (5 mL too little) as 30 mL (5 mL too much). You could decrease the amount of error by using a graduated cylinder, which is capable of measurements to within 1 mL. The error could be decreased even further by using a buret, which is capable of delivering a volume to within 1 drop, or 0.05 mL.