This page shows useful units, constants, and conversions. Often these will be supplied in the problem statements within the course, but they should also be a useful reference.
Prefixes
Metric
\[\rm pico\ (p) = 10^{-12}\] \[\rm nano\ (n) = 10^{-9}\] \[\rm micro\ (\mu) = 10^{-6}\] \[\rm deca\ (da) = 10^1\] \[\rm kilo\ (k) = 10^3\] \[\rm mega (M) = 10^6\] \[\rm giga (G) = 10^9\] \[\rm tera (T) = 10^{12}\] \[\rm peta (P) = 10^{15}\] \[\rm exa (E) = 10^{18}\] \[\rm zetta (Z) = 10^{21}\]
Roman
\[\rm m = 10^3\] \[\rm mm = 10^{6}\] \[\rm quad = 10^{15}\]
Density
\[\rm Water = 1\ g/cm^3 = 1\ g/ml = 1\ kg/L = 1\ metric\ tonne/m^3\] \[\rm \text{Air at Sea Level} = 1.2\ kg/m^3\] \[\rm Crude\ Oil = 0.88 (0.75 -0.98)\ kg/L = 7.34\ lb/gal = 140 kg/bbl\] \[\rm Gasoline = 0.745\ kg/L = 6.22\ lb/gal\] \[\rm Diesel = 0.837\ kg/L = 7.00\ lb/gal\] \[\rm Biodiesel = 0.880\ kg/L\] \[\rm Ethanol = 0.789\ kg/L = 6.58\ lb/gal\] \[\rm Methanol = 0.792\ kg/L = 6.61\ lb/gal\] \[\rm Nat. Gas = 0.717\ kg/m^3 = 44.8\ lb/mft^3\] \[\rm Hydrogen = 0.025\ kg/L (@35MPa); 0.08988\ kg/m^3 (@STP)\] \[\rm Coal \approx 1.32\ kg/L = 1230\ metric\ ton/ha-m = 1800\ sht\ ton/acre-foot\]
Energy Unit Conversions
\[\rm 1\ J = 1\ Nm= 1\ kgm^2/s^2 = 0.239\ cal = 0.74\ ft-lb\] \[\rm 1\ Cal = 1\ kcal = 1000\ cal = 4.187\ kJ = 3.968\ Btu\] \[\rm 1\ KJ = 0.239\ Cal = 0.947817\ Btu \approx 0.95\ Btu\] \[\rm 1\ Btu = 1,055.056\ J = 0.252\ kcal\] \[\rm 1\ kWh = 3.6\ MJ = 3,412\ Btu\] \[\rm 1\ MWh = 3.6\ GJ = 3.412\ mmBtu\] \[\rm 1\ Quad = 10^{15}\ Btu = 1.055\ EJ = 293\ TWh = 25.2\ Mtoe = 0.974\ TCF\] \[\rm 1\ EJ = 10^9\ GJ = 10^{18}\ J = 0.95\ Quad\] \[\rm 1\ TWyr = 31.5\ EJ = 29.86\ Quad\]
Power Unit Conversions
\[\rm 1\ W = 1\ J/s = 3.6\ kJ/hour = 31.5\ MJ/year\] \[\rm 1\ kW = 1.341\ hp = 738\ ft-lb/s\] \[\rm 1\ hp = 745.7\ W = 0.7068\ Btu/s\] \[\rm 1\ TW = 10^{12}\ W = 31.5\ EJ/year\]
Time
\[\rm 3,600\ sec/hour\] \[\rm 730\ hour/month\] \[\rm 365.25\ day/year\] \[\rm 8,766\ hour/year\] \[\rm 31,536,000\ sec/year\]
Numerical Constants
| Ideal gas constant: | \(R = 0.0821 \text{ L} \cdot \text{atm}/(\text{mol}\cdot\text{K}) = 8.31 \frac{\text{J}}{\text{mol}\cdot\text{K}}\) |
| Planck's constant: | \(h = 6.626 \times 10^{-34}\text{J}\cdot\text{s}\) |
| Speed of light: | \(c = 3.00 \times 10^8 \frac{\text{m}}{\text{s}}\) |
| Acceleration due to gravity: | \(g = 9.8 \frac{\text{m}}{{\text{s}}^2}\) |
| Avogadro's number: | \(N_A = 6.02 \times 10^{23}\text{ molecules/mol}\) |
| Specific heat capacity of water: | \(C_{\text{H}_2\text{O}} = 4.18 \frac{\text{J}}{\text{g}\cdot ^{\circ}\text{C}}\) |
| Heat of fusion for water: | \(\Delta H^{\circ}_{\text{fus}} = 6.01\frac{\text{kJ}}{\text{mol}}\) |
| Heat of vaporization for water: | \(\Delta H^{\circ}_{\text{vap}} = 44.0\frac{\text{kJ}}{\text{mol}} = 2.46\frac{\text{kJ}}{\text{g}}\) |
| Wien's displacement constant: | \(b = 0.0029\text{ m}\cdot \text{K}\) |
| Stefan-Boltzmann's constant: | \(\sigma = 5.67 \times 10^{-8}\frac{\text{W}}{\text{m}^2 \cdot \text{K}^4}\) |
| Boltzmann's constant: | \(k_\text{B} = 1.38 \times 10^{-23} \frac{\text{J}}{\text{K}}\) |
| Faraday's constant: | \(F = 96,485 \frac{\text{C}}{\text{mol}}\) |
| Mass of a proton: | \(m_p = 1.67 \times 10^{-27}\text{ kg}\) |
| Mass of an electron: | \(m_e = 9.11 \times 10^{-31}\text{ kg}\) |