# Chemical Calculator

## Introduction

Chemical Calculator provides a set of tools that aid in preparation of solutions from chemical substances, liquid chemicals, or concentrated stock solutions.

## Molarity, mass, and volume

The calculations of molarity (molar concentration), mass, and dilution volume of a chemical substance are based on the equation:

 molar concentration [mol·l-1] = mass [g] molar mass [g·mol-1] · volume [l]

Note that the molar mass is always required for the calculations. The program will report an error if the molar mass value is missing.

## Percentage and molarity

The "Percentage and molarity" calculator provides two options: % w/v (weight in volume) and % v/v (percents of volume). The first option is used for substances dissolved in a solvent. The value describes the amount by weight (mass) of a solid substance dissolved in a measured quantity of liquid. Percent w/v expresses the number of grams of a substance in 100 ml of solution. As in this case the percentage directly defines the weight of the substance in a volume unit, the molarity can be calculated without knowing the mass density of the solution:

 molar concentration [mol·l-1] = percent w/v[%] · 10 molar mass [g·mol-1]

In the second case, the % v/v describes the volume fraction of a liquid mixed with another liquid. To calculate the molarity of the liquids, the weights have to be derived from mass density of the solution:

 molar concentration [mol·l-1] = mass density[kg·l-1] · percent v/v[%] · 10 molar mass [g·mol-1]

Again, the molar mass is always required for the calculations and the program will report an error if the molar mass value is missing.

## Dilution of a stock solution to a working concentration

This calculator gets the results with a simple propotion equation:

 stock solution volume = target concentration stock solution concentration · target volume

Conversions between molar concentration units and mass per volume units are done with the first equation stated on this page.

## Dilution to a desired concentration

Dilution of a whole solution to a certain target concentration is calculated with the formula:

 volume to add = ( initial concentration final concentration - 1 ) · initial volume

Conversions between molar concentration units and mass per volume units are again done with the first equation stated on this page.

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