This document discusses acids and alkalis. It notes that ancient Egyptians and Greeks observed that some substances taste sour while others feel slippery. Scientists later named sour substances "acids" and slippery substances "alkalis." Examples of acids found in nature include citric acid in oranges and lactic acid in muscles. Vinegar contains ethanoic acid. Acids can be classified as organic, produced by living things, or mineral. Common alkalis include sodium hydroxide, calcium hydroxide, and limewater. Concentrated solutions of acids and alkalis are corrosive, while dilute solutions are irritants. Alkalis are found in household cleaners and react with skin fat to produce soap-like substances.

1. Acids and Alkalis
Chapter 10
Chemistry
(1st week)

2. - Ancient Egyptians and Greeks that some substances taste sour and
some feel slippery.
- Example: Vinegar is sour
Lime made from burning of seashells is slippery.
Potash found in the ashes of burnt wood is slippery.
- Scientists called the substance that tastes sour Acids.
- The word acid came from the word Acidus which is the latin word for
sour.
- They also named the substances that feel slippery Alkali, which was
developed from al-qaliy (an Arabic word meaning ‘the ashes’).
- N.B. A lot of investigative work in chemistry was done in Islamic
countries, starting about 1200 years ago.
- The greatest of the muslim chemists at that time was Jabir ibn
Haiyan.

3. Examples of Acids & Alkalis in our daily lives

4. Acids
- Most people think of acids as corrosive.
- This is true for many acids, but, some acids are found in our food
(they give food their sour taste).
- Many acids are found in living things

5. Acids can be found in:
Plants Animals
- Orange and lemon juice Citric acid
- Grapes Tartaric acid
- Citrus fruits and Ascorbic acid
blackcurrants (Vitamin C)
- Nettle stings Methanoic acid
- Mammalian stomach Hydrochloric acid
- Muscles during Lactic acid
vigorous exercise
- Urine Uric acid
- Ant sting Methanoic acid

6. Acid in vinegar
- Ethanoic acid is found in vinegar.
- Ethanoic acid is also produced when wine becomes sour .
- Wine contains ethanol and some dissolved oxygen. Over a period of
time oxygen reacts with ethanol and produces Ethanoic acid.
Ethanol + Oxygen Ethanoic acid
- The above chemical reaction happens more quickly if the wine bottle
is left uncorked.

7. Organic acids and mineral acids
Acids can be classified into:
Organic acids Mineral acids
- Are acids produced by plants and
animals.
- Are acids not produced by living things.
- Their discovery began with the works of chemists such
as Geber.
- The 1st mineral acid to be discovered was nitric acid.
- Nitric acid was used to separate silver and gold (The
silver dissolved but not the gold).
- Later sulfuric acid and then hydrochloric acid where
discovered.

8. Alkalis
Examples of alkalis Uses
Sodium hydroxide and potassium
hydroxide solution
Used in laboratories.
Calcium hydroxide (lime) Used in industries to make bleach
and whitewash.
Weak sol. Of calcium hydroxide (lime
water)
Test for co₂ in breath

9. - A concentrated solution has a greater amount of dissolved
solute than a dilute solution.
- Example: A solution made up of 3 tablespoons of sugar
dissolved in 50 ml of water is concentrated.
A solution made up of 1 tablespoon of sugar dissolved
in 50 ml of water is dilute.

10. - A concentrated solution of an alkali is corrosive.
- A concentrated solution of an acid is also
corrosive.
- A dilute solution of an acid or an alkali are
irritant.
- Dilute solutions of alkali, such as sodium
hydroxide, react with fat on the surface of the
skin and change it into substances found in soap.

11. - House hold cleaners used of metals, floors and
ovens contain alkalis and must be handled
carefully.