Chapter 1- Acids And Alkalis And Metal Reactions Flashcards
Know the taste of acids:
Sour.
Names of household and laboratory acids:
Household acids: Citric acid (lemon), ethanoic acid acid (vinegar) and carbonic acid (fizzy drinks).
Laboratory acids: Sulphuric acid and nitric acid.
Why some acids are more dangerous than others?
Because the stronger the acid ( lower PH) the more strong it is.
Meanings of some safety symbols:
Flammable: This is probably one of those self-explanatory signs – chemicals labeled with this are flammable and you should store them accordingly. Some laboratories have separate storage facilities for such chemicals e.g. in our lab we have special security storage cabinets outside the lab for storing the large bottles.
When you use such chemicals make sure you keep them away from any oxidizing substances, flames or sparks. You should also wear eye protection when working with highly flammable substances. Some examples of flammable chemicals we regularly use are ethanol and isopropanol for plasmid preparation.
Corrosive: They are strong chemicals that can corrode into your skin or any other substances. There are many chemicals in our daily laboratory life that belongs to this category.
Strong acid (sulfuric acid etc.) and strong alkali (sodium hydroxide etc.) solutions are both corrosive. The ?-mercaptoethanol you use for reducing the disulfide bonds of your protein before running a SDS page or the crystal violet dye you use for staining your bacteria are also corrosive (along with their other individual hazards). One drop of these corrosive substances can cause you serious eye damage! When working with corrosive substances you should use precaution – non-corrosive gloves, eye protection and lab coats are all musts.
Toxic: These are highly harmful substances and, in extreme cases, can even cause death if you swallow, inhale or absorb them through your skin.
Examples of toxic chemicals include the HCl you use for adjusting your buffer to the right pH and the universal pH indicator methyl orange. You should always use eye protection, gloves, and a face mask to prevent inhalation when working with toxic substances. And don’t forget: handle the chemical inside a fume cupboard.
Irritant: These substances can irritate your eyes and skin causing itchiness, soreness, redness and blistering. Don’t mistake them for harmless either, they can also cause toxicity if you inhale or swallow them.
For example, the calcium chloride you use for making your competent cells and the SDS for your protein gels both are irritants. You should be careful while preparing solutions containing irritants and make sure you protect yourself properly.
What are alkalis?
Another type of dangerous chemical.
Examples of common alkalis:
Toothpaste
Baking soda
Bleach
Soap
What is an indicator?
An indicator is due that changes colour depending on whether it’s in is an acid or an alkali.
Names and colour changes of some indicators:
Litmus paper: Acid= Red
Alkali= Blue
Universal Indicator: Strong acid= Red
Weak acid= Acid
