The following calculators are to assist you in determining measurements for chemical recipes.

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1. Molarity to Dry Mass
   1. This calculator is designed to output mass measurements when you insert your desired molarity.
2. Molarity to Volume
   1. This calculator is designed to output volume measurements when you insert your desired molarity. It assumes you already have solutions of known molarity.
3. Molarity to Percent Mass Per Volume
   1. This calculator is designed to output volume measurements when you insert your solution's molarity and solute's molecular mass. It assumes you already have solutions of known molarity.
4. Percent Mass Per Volume to Molarity
   1. This calculator is designed to output volume measurements when you insert your desired molarity and solute's molecular mass. It assumes you already have solutions of known mass/volume percent.
5. Percent Mass Per Volume to Dry Mass
   1. This calculator is designed to output mass measurements when you insert your desired percent mass and solute's molecular mass.
6. Percent Mass Per Mass ↔ PP(M,B,T)
   1. This calculator is designed to convert between mass percent and parts per million, billion, or trillion.
7. Helps for the Recipe Calculators
   1. This calculator outputs the mass of a molecule, given the names and amounts of each element present.

The following is definitions of and information about chemistry concentration.

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1. General information
   1. Concentrations can be expressed in numerous units. Some of these units can be a source of confusion.
   2. For example, when working in air concentration 1 ppm = 1 volume/10⁶ volumes or 10^-6 atm/1 atm.
   3. However, when working in liquid concentration 1 ppm = 1 gram of solute/10⁶ grams of solvent.
   4. To avoid confusion, the terms ppmv and ppmw are commonly used to designate part per million by volume and part per million by weight respectively.
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   6. Following are definitions of commonly used units and calculators to convert one concentration to another.
   8. Molarity (M)
      1. This unit of conversion relates the number of moles of solvent to a liter of solution.
      2. Molarity = moles of solvent/Liter of solution
      3. For instance: 2.5 moles of dissolved particles in 5 Liters of liquid solution constitute a 0.5 mol/L (or M) solution (0.5 molar solution)
   9. Molality (m)
      1. This unit of conversion relates the number of moles of solvent to a kilogram of solution.
      2. Molality = moles of solvent/Kg of solution
      3. For instance: 2.5 moles of dissolved particles in 5 Kg of solution constitute a molality of 0.5 mol/Kg (or m) (0.5 molal solution).
         
   10. Weight Percentage (w/w%)
       1. This unit of concentration is often used for concentrated solutions of acids and bases. It is defined as the weight of solute times 100 divided by the total weight and is often abbreviated as w/w%.
       2. w/w% = grams of solute x 100 / (grams of solvent + grams of solute)
       3. For example: if a label indicates a concentration of 25% by mass, then it contains 25 grams of solute and 75 grams of solvent.
   11. Volume Percentage (v/v%)
       1. This unit of concentration is most useful when liquid-liquid solutions are prepared. It is defined as the volume of solute times 100 divided by the total volume and is often abbreviated as v/v%.
       2. v/v% = volume of solute x 100 / (volume of solvent + volume of solute)
       3. For example: if a label indicates a concentration of 25% by volume, then it contains 25 mL of solute and 75 mL of solvent.
   12. Weight Percentage 2 (w/v%)
       1. This unit of concentration is the least specifically named, but the most common when diluting solvents in liquid. If w/w%, w/v% or v/v% is not specified, then w/v% is assumed.
       2. w/v% = grams of solute/100mL solution
       3. For example: if a label indicates a concentration of 2.5%, then it contains 2.5 grams of solute per every 100 mL of solution.
   13. Parts Per Million (ppm)
       1. This unit is a way of expressing very dilute concentrations of substances. Just as per cent means out of a hundred, so parts per million or ppm means out of a million. ppm is commonly used to describe very small amounts of contaminants.
2. Solubility and dissolution
   1. Solubility is an important property to consider when thinking about mixing two or more substances together. The solubility of a solute is the maximum quantity of solute that can dissolve in a certain quantity of solvent at a given temperature. Solubility is expressed as a maximum concentration.
   2. The main factors that have an effect on solubility are:
   3. • The nature of the solute and solvent -- molecular size and polarity
      • Temperature : Generally, an increase in the temperature of the solution increases the solubility of a solid solute. A few solid solutes, however, are less soluble in warmer solutions. For all gases, solubility decreases as the temperature of the solution rises.
      • Pressure (for gaseous solutes)
   4. When a solution at equilibrium can not hold any more solute, it is said to be saturated.
      Under special conditions, solutions may hold more solute than the solvent can normally dissolve. This is called supersaturation.
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   6. The rate of dissolution is determined by :
      
      • the size of the particles -- When a solute dissolves, the action takes place only at the surface of each particle. When the total surface area of the solute particles is increased, the solute dissolves more rapidly. Breaking a solute into smaller pieces increases its surface area and hence its rate of solution.
      • stirring -- With liquid and solid solutes, stirring brings fresh portions of the solvent in contact with the solute, thereby increasing the rate of solution.
      • the amount of solute already dissolved -- When there is little solute already in solution, dissolving takes place relatively rapidly. As the solution approaches the point where no solute can be dissolved, dissolving takes place more slowly.
      • temperature -- For liquids and solid solutes, increasing the temperature not only increases the amount of solute that will dissolve but also increases the rate at which the solute will dissolve. For gases, the reverse is true. An increase in temperature decreases both solubility and rate of solution.
      
      Generally polar molecules will dissolve in polar solvents and non-polar molecules will dissolve in non-polar solvents. The polar molecules have a positive and a negative end to the molecule. When the solvent molecule is also polar, positive ends of solvent molecules attract negative ends of solute molecules.
      Polar solvents can generally dissolve solutes that are ionic. The negative ion of the substance being dissolved is attracted to the positive end of a neighboring solvent molecules while the positive ion of the solute is attracted to the negative end of the solvent molecule.
      
      
3. Polymer basics
   1. Under Construction
   2. Definition --- all plastic=polymer but not all polymer=plastic (ex: some biological and inorganic molecules)
      large molecule with repeating units (monomer)
      linear/branched
      
   3. Thermoplastic/thermoset
   4. Amorphe/crystallin
   5. condensation/addition
   6. Photoresists (SU8 = epoxy polymer = thermoset) see this page for more information.
   7.