How do you make a chemical solution?

How do you make a chemical solution?
March 27, 2020

Please review the following guide on how to prepare a chemical solution:
https://www.sciencecompany.com/Preparing-Chemical-Solutions.aspx

Glossary, basic terms to understand

Reagent – Any substance used in chemical reactions, analysis or research.
Solute – The substance which dissolves in a solution.
Solvent – The substance which dissolves another to form a solution. For example, in a sugar and water solution, water is the solvent; sugar is the solute.
Solution – A mixture of two or more pure substances. In a solution one pure substance is dissolved in another pure substance uniformly. For example, in a sugar and water solution, the solution has the same concentration throughout, ie. it is uniform.
Concentration – The ratio of solute to solution e.g. 10mg per mL, 10mg/mL, 10mg/cc.
Suspension – Typically a solution is transparent because solute particles are microscopic. A suspension has visible particles.

Introduction to Chemical Solutions

Chemical solutions involve dissolving a reagent in liquid to make it easier to measure, without relying on an expensive or imprecise scale. Assuming the solution is at a uniform concentration, measurement of the reagent can be done precisely using volumetric measurement tools like a beaker or pipette.

Selecting an adequate solvent

If you do not select an adequate solvent your solute will precipitate out of solution or lack uniformity, making handling difficult. The best way to verify a solvent is adequate is through trial and error solubility analysis.

Selecting your concentration

Solutions are easier to make and handle at lower concentrations. If you saturate a solution the solute may precipitate out of solution thus ruining the uniformity. Changing the pH or temperature of your solution can also result in precipitation.

Solution Example: Using mass by volume (m/v)

Formula
The formula for mass by volume (m/v) is: [Mass of solute (mg) / Volume of solution (ml)]

Example
A 10mg/mL NaCl solution has 10 milligrams of sodium chloride dissolved in 1 ml of solution.

Procedure

  1. Select a concentration for your solution e.g. 10mg/mL.
  2. Select a total volume for your solution e.g. 50mL.
  3. Weigh out your solute by multiplying the concentration by total volume e.g. 10mg/mL * 50mL = 500mg.
  4. Select an adequate solvent for your concentration.
  5. Pour your solute into your solvent and mix.
  6. The solute should fully dissolve and the solution should become transparent. If there is sediment or visible particles then the solution is not uniform.

Notes:

  1. The procedure above is simplified. Simply measuring 50mL of solvent and adding 500mg of solute introduces error because adding the solid will change the final volume of the solution. The more correct procedure would be to mix solute with ~80% of your solvent and then add solvent until you reach your desired volume of 50mL.
  2. The most common causes of precipitation include selecting an inadequate solvent, selecting too high a concentration, not using adequate measurement equipment (milligram scale, graduated beaker), mixing multiple solutes together (which will affect pH and lower solubility).
  3. We recommend against heating or incubation, as our products are novel and this can cause an unintended chemical reaction. The solute will also precipitate out as it cools down.

Precipitation and Suspension

What if your solution precipitates? You have a few options. If you selected too high a concentration you can add more solvent or a cosolvent and lower the concentration.

Another option, if the precipitation is minor, is to suspend the precipitate temporarily by agitating (shaking well, stirring vigorously) and then make your volumetric measurement. This will have some error, dependent on the level of precipitation and uniformity.

Several of our premade solutions can precipitate slowly and we indicate this by instructing to shake well before administration on the product label.