Science
Lists of data, formulae and relationships
Data
| Name of constant | Symbol and value |
|---|---|
| Gravitational contstant | $G = 6.67 \times 10^{-11} \text{N m}^2 \text{kg}^{-2}$ |
| Acceleration of free fall (close to earth) | $g = 9.81 \text{m s}^{-2}$ |
| Gravitational field strength (close to earth) | $g = 9.81 \text{N kg}^{-1}$ |
| Electronic charge | $e = -1.60 \times 10^{-19} \text{C}$ |
| Electronic mass | $m_e = 9.11 \times 10^{-31} \text{kg}$ |
| Electronvolt | $1 eV = 1.60 \times 10^{-19} \text{J}$ |
| Unified mass unit | $u = 1.66 \times 10^{-27} \text{kg}$ |
| Planck constant | $h = 6.63 \times 10^{-34} \text{J s}$ |
| Speed of light in a vacuum | $c = 3.00 \times 10^{8} \text{m s}^{-1}$ |
| Molar gas constant | $R = 8.31 \text{J K}^{-1} mol^{-1}$ |
| Boltzmann constant | $k = 1.38 \times 10^{-23} \text{J K}^{-1}$ |
| Avogadro constant | $N_A = 6.02 \times 10^{23} \text{mol}^{-1}$ |
| Permittivity of free space | $ \epsilon _{0} = 8.85 \times 10^{-12} \text{F} \text{m}^{-1}$ |
| Permeability of free space | $\mu _0 = 4\pi \times 10^{-7} \text{N} \text{A}^{-2}$ |
Read more...Published on 12th March 2013.
Tissue Culture Vessel Comparison
This table lists all major tissue culture vessels with their corresponding areas, ratios and volumes.
| Culture Vessel | Surface area (cm²) | Typical volume (mL) | Ratio to T-75 | Ratio to 6-well plate |
|---|---|---|---|---|
| 96-well plate | 0.3 | 0.2 | 0.0040 | 0.03 |
| 48-well plate | 0.7 | 0.5 | 0.0093 | 0.07 |
| BD Falcon CultureSlide (per well) | 0.7 | 0.5 | 0.0093 | 0.07 |
| 24-well plate | 2 | 0.7 | 0.026 | 0.2 |
| 12-well plate | 4 | 0.7 | 0.053 | 0.4 |
| BD Falcon CultureSlide (per slide) | 5.6 | 4 | 0.075 | 0.46 |
| 6-well plate | 10 | 2 | 0.13 | 1 |
| 35 mm dish | 10 | 2 | 0.13 | 1 |
| 60 mm dish | 20 | 3.5 | 0.26 | 2 |
| 100 mm dish | 60 | 10 | 0.80 | 6 |
| 150 mm dish | 140 | 23 | 1.87 | 14 |
| T-25 flask | 25 | 4 | 0.33 | 2.5 |
| T-75 flask | 75 | 12 | 1 | 7.5 |
| T-175 flask | 175 | 28 | 2.3 | 17.5 |
Read more...First published on 25th June 2011 and last modified on 17th March 2014.
Molarity of common concentrated solutions
Lab solutions are often purchased as concentrated solutions of a standard strength. This strength is often given as a percentage (e.g. w/w) however it is usually more convenient to know these as molarity. The calculations are simple enough but are tedious and require knowledge of the density of the solution as well as molecular mass of the molecule.
This list includes commonly used commercially available solutions and their molar equivalent.
- Glacial acetic acid - 17.47M
- 98-100% formic acid (density = 1.22 g/cm³) - 26.51M
- 70% perchloric acid (density = 1.664 g/cm³) - 11.65M
- 60% perchloric acid (density = 1.535 g/cm³) - 9.17M
- 35% NH3OH (ammonium hydroxide) (by mass) - 18.08M
- 70% HNO3 (nitric acid) (density = 1.4 g/cm³) - 17.46M
- 32% HCl (hydrochloric acid) (density = 1.159 g/cm³) - 10.17M
- 38% HCl (hydrochloric acid) (density = 1.189 g/cm³) - 12.39M
Read more...First published on 30th May 2011 and last modified on 19th May 2013.
Lab freezing bath temperatures
Freezing mixtures in the lab are often made from a mixture of either liquid nitrogen or dry ice with a solvent. If using liquid nitrogen this forms a slurry. The viscosity of this slurry is dependent on the solvent or mixture of solvents used. If using dry ice, you generally end up with an equilibrium where a small amount of dry ice is sat in a cold bath of solvent. By varying the solvent used, different temperatures can be achieved.
There has been lots of good work done in the past in determing the temperatures of these baths and there are links for further reading in the references below.
Read more...First published on 9th November 2010 and last modified on 25th June 2011.
Isotope Half Lives and Energies
This page is not meant to be a comprehensive list of all information that is required to work safely with radiation. It is only a small fraction of isotopes available but it covers the commonly used isotopes in my research institute. I will add other data if requested though.
Read more...First published on 3rd February 2009 and last modified on 25th June 2011.
Centrifuge RPM and RCF Calculator
This calculator allows you to inter-convert between RPM and RCF for any centrifuge with a known rotor size. There is a limited list of rotors below for manual rotor selection.
You are currently solving for rotational speed (RPM)
Read more...First published on 21st September 2008 and last modified on 25th June 2011.
Standard Deviations
The correct manipulation of standard deviations is an often overlooked skill. When working with data sets it is cruicial that the correct manipluations are applied for the results to be valid.
This page demonstrates several methods for combining standard deviations correctly with some worked examples.
Addition and subtraction of values with standard deviations
Consider this problem where each value (a, b or c) has an associated standard deviation or error (Da, Db or Dc respectively). We are trying to calculate the correct value for z ± Dz:
Read more...First published on 21st September 2008 and last modified on 16th March 2011.
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