List four precautions regarding the use of general supply botties of chemicals.

Question

List four precautions regarding the use of general supply botties of chemicals. 1. Name two souroes of sample contamination 1. Name two sources of sample contamination 2 List five general rules for handling chemicals. 6. What is the correct procedure for mixing an acid solution with water? 3. What is the most important general rule to follow when discarding chemicals and solutions? 7. List four reasons for not dipping litmus paper or pH paper into solutions. . What is the best procedure for weighing solids?

Explanation / Answer

1) Sample contaminants: Sodium ions and oils from your skin. Examples of particulate contamination are dust from the air, exfoliated skin, hair, and dandruff.

2) General rules for Handling chemicals:

1. Follow all established procedures.

2. Be cautious and plan ahead. Think about what could go wrong and pay close attention to what you’re doing while you work.

3. Always use required PPE—and inspect it carefully before each use to make sure it’s safe to use. Replace worn out or damage PPE; it won’t provide adequate protection.

4. Read labels and the material safety data sheet (MSDS) before using any material to make sure you understand hazards and precautions.

5. Use all materials solely for their intended purpose. Don’t, for example, use solvents to clean your hands, or gasoline to wipe down equipment.

6. Never eat or drink while handling any materials, and if your hands are contaminated, don’t use cosmetics or handle contact lenses.

7. Read the labels and refer to MSDSs to identify properties and hazards of chemical products and materials.

8. Keep you and your work area clean. After handling any material, wash thoroughly with soap and water.

9. Learn about emergency procedures and equipment. Understanding emergency procedures means knowing evacuation procedures, emergency reporting procedures, and procedures for dealing with fires and spills. It also means knowing what to do in a medical emergency if a co-worker is injured or overcome by chemicals.

3)General rules Discard in chemicals and solutions:

Always wear protective clothing, including a face mask, rubber gloves, and apron when handling corrosive chemicals. Check gloves for pinholes before putting them on. following rules to avoid contamination:

4)Best procedure for weighing solids:

5)Precautions regarding the supply bottles:

1.Take an appropriate container to the reagent shelf where the liquid is kept. Make the actual transfer at a nearby sink to avoid spills on the laboratory bench, shelf, or floor.
2.If the general supply bottle is equipped with a dropper, use the dropper, but be sure that it never touches the container or its contents.
3.If the general supply bottle is equipped with a stopper, the stopper should either be held during the transfer or placed on its flat top. Do not lay the stopper on its side on the laboratory bench or shelf.
4.Do not put your dropper or capillary pipette into the general supply bottle. Pour chemicals from the general supply bottle into a labeled container for personal use.
5.Be sure the appropriate stopper is returned to the supply bottle.
6.Use a clean dropper to dispense liquids from your labeled container."

6) mixing of acid solution with water:

You should add acid to water very slowly in cold condition(Exothermic reaction).

7)Not Dipping litmus paper or PH paper in solution:

1) it could soak upwards onto your hands
2) your fingers could come in contact with the acid
3) it's unnecessary, only a small drop of acid is needed for the litmus test.

8)Beginning of each Laboratoty session:

• Prepare questions and examples to work from during the lab.

9) What should perform after each precipitation:

Remove solid from the ions that remain in solution. You will need to carefully wash the precipitate and decant the solution to remove all soluble ions. You will use pH paper when you acidify and basify your samples. Finally, you will heat in a water bath to perform some reactions. Be sure to use clean glassware to avoid contamination of your sample. Wash glassware with soap and rinse with distilled water.

10) six precautions for centrfuge:

Make sure that the tubes are good and don't have any cracks or chips in them.

Balance the tubes--make them all have the same mass.

Arrange tubes in the rotor in a symmetrical way so that the rotor is balanced.

Don't open the centrifuge while the rotor is spinning.

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