The idea. This is not a presentation on how to clean yourself with chemicals. Rather, it is an introduction into the safety practices of chemistry. As with any situation, chemistry has a set of rules to follow in order to learn safely.
The rules. The first rule of chemistry is: DO NOT MIX ANYTHING UNTIL YOUR INSTRUCTOR TELLS YOU TO! The second rule of chemistry is: DO NOT MIX ANYTHING UNTIL YOUR INSTRUCTOR TELLS YOU TO!
Key concepts. In this presentation, you will know: How to safely mix chemicals. How to safely quantify chemicals What to do when splashed or exposed to chemicals accidently. Special handling procedures. What an MSDS is.
Mixing chemicals Normally, mixing chemicals does not require any special procedures or know-how. This includes dissolving salts or mixing compatible liquids. However, there are a couple of terms to know. Solvent- this is the medium in which your material is being dissolved. (e.g. water) Solute- this is the material to be dissolved. (e.g. NaCl)
Mixing chemicals (con’t) Before you get started, make sure all of your calculations are done and your work area is free from clutter. This is to prevent any contamination of the experiment and to prevent any accidents. When mixing chemicals, you will always want to add the more concentrated solution to the least concentrated solution.
Mixing chemicals (con’t) Concentrated strong acids or bases require special attention: Due to the enthalpy of dissociation (the heat released when the solute is dissolved,) these chemicals need to be added in a certain way. When dissolving solids in water, add the solute in small amounts and mix. This will prevent a build up of heat and allow for even distribution of the chemical in the water.
Mixing chemicals (con’t) When mixing a liquid concentrated acid or base to water, always add the acid or base to the water. Not the other way around. The heat released when the concentrated solution dilutes may be enough to cause the solution to boil or become to hot to handle. Always stir the water continuously when you add the acid or base. When you have finished mixing the chemicals, immediately label and properly store or use your chemical.
Quantification. This is the way in which we obtain physical properties of a chemical. It is important to NEVER smell, touch, or taste a chemical unless your instructor tells you to. When you can, you will only smell. Plus this has a method. In order to smell a chemical, gently waft the fumes from the chemical towards you and smell. Never inhale chemical fumes directly. This can lead to injury.
Chemical exposure. As hard as we try to avoid it, accidents happen. If it does happen to you, follow this procedure: First, tell your instructor. He or she will make a decision on what to do next. If you splashed some of the chemical on your skin, flood the area with water. This will dilute and wash away the chemical in an effort to prevent or stave off any damage.
Chemical exposure (con’t) If you get some chemicals in your eye, wash your eye with water for a minimum of fifteen (15) minutes. Your instructor will get all the needed information for the EMT’s when they arrive. If you are splashed with a large amount of chemical, or the chemical saturates your clothing, use the chemical shower. This shower is designed to flood the exterior of your body to dilute the chemical or wash it away.
Chemical exposure (con’t) If the chemical fumes are causing you any of the following problems, let your instructor know. Headache Pain at the site of (possible) exposure Difficulty breathing Any signs of an allergic reaction.
Special handling procedures. Some chemicals are not compatible with one another. It is important to ,once again, not mix any chemicals without the explicit instructions from your instructor. Never store concentrated acids and bases together. Never mix and chemicals in the Sodium (Na) or Calcium (Ca) columns with water.
Special handling procedures (con’t.) When boiling a solution in glassware, use a boiling chip. This is a small piece of rough glass that will allow bubbles to form. The interior surface of glassware is often too smooth to allow bubbles to form. This can lead to the solution superheating; resulting in a sudden, violent boil called “bumping”
MSDS MSDS stands for Material Safety Data Sheet. The MSDS is a sheet, or sheets, of information about a single chemical. It includes the special handling procedures for a given chemical, its physical properties, and any other needed information about the chemical. The collection of MSDS can be found in the same storage area as the chemicals themselves at minimum. It must also be in plain sight. A copy of the MSDS must be given to a person on request.