Soap:
Sodium hydroxide is traditionally used in soap
making(cold processes soap,saponification).
It was made in the nineteenth century for a hard surface rather than liquid product because it was easier to store and tranship .
Food preparation:
Most yellow coloured Chinese noodles are made with lye-water but are commonly mistaken for containing egg.
CITRIC ACID
Food additive
As a food additive, citric acid is used as a flavouring and preservative in food and beverages, especially soft drinks
Citric acid can be used in food colouring to balance the pH level of the normally basic dye.
SALICYLIC ACID
Medicinal uses:
Salicylic acid is known for its ability to ease aches and pains and reduce fevers. These medicinal properties, particularly fever relief, have been known since ancient times, and it was used as an anti-inflammatory drug
In modern medicine, salicylic acid and its derivatives are used as constituents of some rubefacient products. For example, methyl salicylate is used as a liniment to soothe joint and muscle pain, and choline salicylate is used topically to relieve the pain of aphthous ulcers.
Skin care products:
salicylic acid is a key ingredient in many skin-care products for the treatment of acne, psoriasis, calluses, corns, keratosis pilaris, and warts .
SODIUM BENZOATE
Preservative:
It is used most prevalently in acidic foods such as salad dressings (vinegar), carbonated drinks (carbonic acid), jams and fruit juices (citric acid), pickles (vinegar), and condiments. It is also found in alcohol-based mouthwash and silver polish. 
MONOSODIUM GLUTAMATE
Food additive: 
- Canned, frozen, or dried prepared food
- Common snack foods such as flavoured jerky, flavoured potato chips (crisps) and flavoured tortilla chips .
- Done by Zong Lin , Tommy & Dylan .
