Chemistry in daily life - vinegar

Vinegar, liquid consisting mainly of water and acetic acid  (typically 4-18% acetic acid by mass) with a molecular form CH3COOH, is very useful in our daily life. Vinegar has been used as a cooking additive, as a medicine, a cleaning agent, and even for a herbicide.

Although vinegar is , as a acid, mildly corrosive to some metals including iron, magnesium, and zinc, forming hydrogen gas and salts called acetates:
                      Mg(s) + 2CH3COOH(aq) →  Mg(CH3COO)2(aq) + H2(g)
many times, in order to clean old copper coin, you leave the old coin in a plastic container containing some vinegar solution with a little bit of salt (NaCl)) for some time until we see the coin becoming pink and shiny. The chemical reactions involved are:

                           CuO(s) + 2CH3COOH(aq)  --> Cu(CH3COO)2(aq) + H2O(l)

                           Cu(OH)2(s) + 2CH3COOH(aq) --> Cu(CH3COO)2(aq) + 2H2O(l)

In households, vinegar is often used as descaling agent or a chemical descaler to remove limescale from metal surfaces of boilers, water heaters, and kettles with hot water. Typical chemical reaction is that vinegar reacts with  metal carbonate compounds present in the scale:
                          CuCO3(s)  + 2CH3COOH(aq)  --> Cu(CH3COO)2(aq) + H2O(l) + CO2(g)

                       Cu2CO3(OH)2(s) + 4CH3COOH(aq)  --> 2Cu(CH3COO)2(aq) + 2H2O(l) +  CO2(g)

In hard water areas, a cup of vinegar is add to a gallon of tap water for watering acid loving plants like rhododendrons, gardenias or azaleas.

The vinegar increases soil acidity and release iron in the soil for the plants to use. Also vinegar is used to neutralize garden lime. Rinsing your hands liberally with white distilled vinegar after working with garden lime will avoid rough and flaking skin. To clean pots before repotting, rinsing pots with vinegar remove excess lime.