Page 205 - Demo

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Acid Safety
203
Acid Safety, continued
• Concentrated phosphoric acid has a melt- ing point close to ambient temperature and may also crystallize in a cool store- room. Phosphoric acid is hygroscopic and will absorb water over time. Keep tightly sealed.
Transporting
• Secondary containment is critical to prevent major spills or accidents when transporting acids. Use PVC-coated acid bottles or unbreakable bottle carriers.
• A good habit is to check the acid bottle for cracks before touching or picking it up. Also check for spilled acid on the handle or bottle.
• Always carry large acid bottles with one hand underneath the bottle and the other hand around the neck or finger hole. This keeps the bottle closer to your body and decreases the risk of hitting a sharp object, like a desk corner, and breaking the bottle.
• Plastic or rubber safety bottle carriers should be used whenever acids are trans- ported from one laboratory to another or from the storeroom to a laboratory.
• If a cart is used to transport hazardous chemicals, including acids, place compat- ible chemicals inside an unbreakable secondary containment vessel, such as a plastic tote. The cart should be equipped with guardrails to prevent plastic totes or bottles from sliding off the cart.
• If hazardous chemicals are moved from one floor to another, use an elevator if possible. Only the person transporting the chemicals should be on the elevator. Although elevator accidents are rare, should a dangerous material be released in an elevator while passengers are trapped inside, the results could be catastrophic.
Preparation of Acid Solutions
See page 214.
To Prepare a Solution
1. Add the appropriate amount of acid to about 2⁄3 of the required amount of distilled or deionized water.
2. Always add acid to water! Never add water to concentrated acids. The acid may splatter and generate acidic steam.
3. Always use borosilicate (e.g., Pyrex®) glassware.
4. Stir to mix the solution.
5. Once the solution has cooled to ambient temperature, dilute the solution to the proper volume with water.
6. Use a volumetric flask for accuracy if needed.
7. When diluting sulfuric acid, place the boro- silicate beaker or flask in an ice bath. The heat of dilution of sulfuric acid is very high and may melt plastic containers or crack non-borosilicate glassware.
Using and Dispensing Acids
• Always review the Safety Data Sheet (SDS) before using any hazardous material in the laboratory.
• Students should dispense acids from smaller bottles to limit spills and fumes.
• Use lab mats and or plastic trays when dispensing acids to contain acid spills and drips.
• Dispense acids, especially hydrochloric, nitric, and acetic acids, in an operating fume hood.
• During lab, set the acid bottle in a central dispensing location and have students bring a graduated cylinder or test tube to the dispensing area. This will help to mini- mize spills and accidents and will limit the amount of acid that is transported back to the lab bench.
• Instruct students to remove only the amount of acid needed for the experiment from the reagent bottle. Chemicals are never added back to the reagent bottle.
• Have acid spill clean-up materials readily available whenever acids are used.
• Attach a test tube to the reagent bottle to store the pipet for dispensing an acid.
• Acids are corrosive and will eat through most fabrics, resulting in small holes in clothing. This process does not occur instantly but rather over several hours and may not become apparent until the clothes are washed. Always wear a chemical-resis- tant apron or laboratory coat when working with acids.
Personal Protection Equipment and Safety Aids
• Chemical splash goggles must be worn anytime acids or acid solutions are used. Safety glasses are not adequate protection.
• Good ventilation should be available when- ever hydrochloric, nitric, or acetic acid will be used in the lab.
• Spill control materials (sand, absorbent, and neutralizer) must be available when- ever acids or acid solutions are used.
First Aid
• Always seek professional medical attention upon exposure to any hazardous chemical, especially concentrated acids.
• The best first aid for any chemical exposure to body tissue or eyes is immediate dilution with water.
• If an acid is splashed in the eyes, use an eyewash to irrigate the eyes for at least 15–20 minutes. Make sure the eyelids are held open to properly irrigate them. Ask the victim to look up, down, and sideways to better reach all parts of the eye.
• If an acid is splashed onto bare skin, rinse with water for at least 15–20 minutes.
• If an acid is splashed onto clothing, remove the clothing immediately before the acid soaks through the clothing and reacts with the skin. If an acid splashes onto your skin and clothing, immediately begin rinsing the affected skin with water (safety shower is ideal) and then begin to remove affected clothing. Modesty must take a back seat to the potential chemical burns that
can occur.
• If acid is ingested, the primary goal is to dilute the acid in the stomach and prevent further injury caused by vomiting. If the victim is conscious, immediately have the victim rinse their mouth out with water. Have the victim drink one or two cups of water or milk. Gastric antacids such as milk of magnesia or aluminum hydroxide can also be given. Do not induce vomit- ing, do not try to neutralize the acid with a strong base, and do not give the victim any sodium bicarbonate or any carbon- ated drinks. Call poison control center (1-800-222-1222) or hospital emergency room and follow their directions.
Always add acid to water...
Always dilute and neutralize acids before disposal.
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Nitrile rubber gloves are acid-resistant and are the best choice to use when handling concentrated acids. However, any plastic or vinyl glove will provide some protection against the occasional splash, small spill, and splatter that may occur when using or dispensing acids.
Operating eyewashes must be available in Disposal
any classroom or laboratory where acids or acid solutions are used. An approved eyewash must treat both eyes and provide clean potable water for at least 15–20 minutes.
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Always dilute and neutralize all acids before disposal.
See Flinn Suggested Disposal Methods #24a and #24b in the current Flinn Scientific Catalog/ Reference Manual for detailed disposal procedures and warnings.