# Science

## Lists of data, formulae and relationships

### Data

Name of constantSymbol 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 VesselSurface area (cm²)Typical volume (mL)Ratio to T-75Ratio to 6-well plate
96-well plate0.30.20.00400.03
48-well plate0.70.50.00930.07
BD Falcon CultureSlide (per well)0.70.50.00930.07
24-well plate20.70.0260.2
12-well plate40.70.0530.4
BD Falcon CultureSlide (per slide)5.640.0750.46
6-well plate1020.131
35 mm dish1020.131
60 mm dish203.50.262
100 mm dish60100.806
150 mm dish140231.8714

## 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

## 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.

## 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.

## 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.

Variable to solve for Value Units
Rotational speed RPM
G-force (RCF) xg

You are currently solving for rotational speed (RPM)

## 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: 