Look here for information about measurement systems, units, and related topics, as well as online calculators and software for unit conversions. You'll also find calculators for pH, temperature, molecular weight, and other chemistry figures.
Metric units of measurement are all based on units of ten. Here is a list of the most common metric unit prefixes.
Here's a handy online converter for temperatures. Simply enter your known temperature (Kelvin, Celsius, Fahrenheit) and the other values will appear. It's much easier than trying to remember the formulas or do the math!
Sometimes you just need to use a quickie calculator! Here's one for addition, subtraction, multiplication, and division.
Use these printable worksheets to practice unit conversions. These pdf questions and answers will test your understanding of metric-metric, metric-English, and temperature conversions.
Here is a step-by-step tutorial for balancing chemical equations, along with a worked example. This is a must-read for students of general and introductory chemistry!
Do the units for solution concentration confuse you? Get definitions and examples for calculating percent composition by mass, mole fraction, molarity, molality, and normality. I've also included a bit of information on dilutions.
This is an ever-growing collection of worked chemistry problems. The examples are grouped according to subject matter.
This is a set of tables with some useful physical constants, conversion factors, and unit prefixes. They are used in many calculations in chemistry, as well as in physics and other sciences.
Perimeter, surface area and volume formulas are used for many chemistry calculations. You may need to find surface area and volume to determine density and concentration, for example. While it's a good idea to memorize these formulas, here a list of formulas to use as a handy reference.
It's very important to know how to calculate the mean or average of a set of numbers. Among other things, this will allow you to calculate your grade point average. However, you'll need to calculate the mean for several other situations, too.
Take a multiple choice quiz to test your comprehension of units, conversions, and significant figures.
Here is a step by step example of a conversion between metric units. This illustrates how to cancel units to convert measurement units.
How well do you know your metric prefixes? Quiz yourself with this ten question multiple choice self-test.
Perimeter and surface area formulas are part of the math used in common science calculations. You While it's a good idea to memorize these formulas, here is a list of perimeter, circumference and surface area formulas to use as a handy reference.
Scientific notation uses exponents to express numerical figures. Here's an explanation of what scientific notation is, plus examples of how to write numbers and perform addition, subtraction, multiplication and division problems using scientific notation.
This article discusses the use of significant figures in taking measurements and performing calculations. Learn about significant figures, uncertainty, accuracy, precision, rounding, and truncating. Losing significant figures and effects of exact numbers are also described.
Surface area and volume formulas are part of the math used in common science calculations. You may need to calculate surface area and volume to determine density, pressure and concentration, for example. While it's a good idea to memorize these formulas, here a list of surface area and volume formulas to use as a handy reference.
Need a value for a fundamental physical constant? This handy reference table contains commonly used physical constants used in chemistry.
This thermometer is labelled with both Fahrenheit and Celsius degrees. Use it to compare the Fahrenheit and Celsius temperature scales or to look up conversions between them.
Have you ever wondered why lb is used as the symbol for the pounds unit? Here's the answer to the question.
These are online conversions for altitude, temperature, pressure, density, and speed of sound. Many different units are available.
A summary of most of the units of measurement to be found in use around the world today, together with the appropriate conversion factors.
The Indiana University Knowledge Base provides this table of decimal and hexadecimal equivalents for ASCII characters.
Enter a chemical formula and ChemCalc will calculate it molecular formula, molecular mass, exact mass, and elemental analysis will plot an isotopic distribution graph. In addition to the calculator, the site offers FAQs, contact information, mailing lists, table of elements and their atomic mass, and section on known atom groups.
There are online grams-to-moles, moles-to-grams, temperature, and ideal gas converters.
ConvertIt.com's online calculators can perform unit, time zone, and currency conversions. There is also a reference section for geographical locations.
This is a table of conversion factors to convert various units to their SI equivalents. It is not intended for people who prefer to use cgs or English units.
The US Geological Survey provides this table of common metric to English conversions.
The Institute of Chemistry, Berlin, provides this easy to use online calculator for a host of different units. You simply choose input the starting value and unit and select the desired result.
Botanical.com provides these English-to-metric and metric-to-English conversion tables for weights and measures.
Principles used in unit conversions of mg/m3 to ppm for gases and vapors. From the Canadian Center for Occupational Health & Safety.
On-screen conversions transform one international unit to another – including time zones.
From decimal 0 to decimal 255.
Système International history, units, definitions, and prefixes.
Tables and calculations involving vapor-liquid equilibria. From Shuzo Ohe, Science University of Japan.
A lot of information about units and unit conversion; includes also constants, information about SI, and unit prefixes.
Enter formula and get mass; enter mass and get some empirical formulas. From Guillaume Cottenceau, Imperial College of Science, Medicine and Technology.
From NIST, latest values of the constants and background information.
Convert from grit to mesh to microns to inches. From Reade Advanced Materials.
Everything you need to know about SI. A NIST special publication, available as PDF file for download.
From Russ Rowlett, University of North Carolina, a comprehensive dictionary of units of measurement covering the English customary systems, the metric system, and the International System of Weights and Measures (SI).
From NIST, essentials of the SI, background, and bibliography.
Converts metric, imperial, and US measurements.
Online tools calculate exact masses, isotopic abundances, and perform other mass spectroscopy functions. Includes periodic table with mass spectra of elements. From Scientific Instrument Services.
This is an online converter for angles, area, astronomical distance, density, energy, financial interest, force, fractions-to-decimal, heat index, kitchen measures, length, mass, prefixes, power, pressure, resistance, speed, temperature, time, viscosity, volume, weight, wind chill... you name it!
Includes length, mass, and volume conversions.
This site will calculate molecular properties (bond lengths, angles, atomic charges, dipole moment, bond orders, molecular orbital energies) and the best Lewis structure that fits the molecular orbitals. The Lewis structure is given with formal electron pair localized bonds and the hybridization of the atomic orbitals used to form these bonds. The calculations take 1-2 hours to perform.
Easily convert mg/dL to mEq/L for a variety of ions and important biomolecules.
Short descriptions with examples and a Java applet that calculates [H+] and pH. From Gwen Sibert, Roanoke Valley Governor's School.
Science Made Simple provides this program, which performs English to metric conversions for area, length, pressure, stress, speed, temperature, time, volume, weight, and fruit (I had to look that one up... it's apples and oranges).
This site does most conversions, with over 5,000 different units and 30,000 conversions. More unusual choices include clothing size conversions, light units, and number bases.
Converts from hydrogen ion concentration to pH and vice versa. From Henry Bungay, Rensselaer Polytechnic Institute.
SI units, atomic weights, ground states, atomic spectra, nuclear physics data. From National Institute of Standards and Technology.
Interconvert Pa, torr, mm Hg, atm, lb/in2 and more. From the American Vacuum Society.
There is an online converter between Arabic numbers and Roman numerals, dates in Gregorian or Julian calendars, and Roman to Gregorian dates. There is also a self-quiz.
Software for many makes and models of mass spectrometers. Includes wealth of mass spectroscopy information and references including resins used for packing columns, exact mass calculators, supplies, and equipment.
Supports unit conversions from non-SI to SI. From TechExpo.
A freeware units conversion program specifically for engineers, runs under Windows 9x/NT, from Katmar Software.
From NIST, essentials of expressing measurement uncertainty.
It may not be universal, but it is certainly worldwide.
Promoters of US transition to metric system.
This is the site for you if you are calculating probabilities, distributions, frequencies, proportions, correlations, regressions, t-tests, ANOVA, ANCOVA, or are performing other statistical tests.
For computing probabilities, regression analysis, analysis of variance, and other statistical tests. From John C. Pezzullo.
Free unit converter for Windows platforms from ESSCo. Commercial Windows API and COM versions for embedding unit conversions in user applications are also available.
Inches, gauge, and millimeters. From Reade Advanced Materials.
On-screen conversion calculators for length, weight, pressure, and volume.
Applets deliver on-screen conversions. From Jan Derk Stegeman.
