Qualitative Characteristics of Acids and Bases

Common Characteristics

• Bases are generally bitter tasting whereas acids have a sour taste. Bases are odorless, but acids can be pungent. Bases feel slippery while acids sting or burn. Some common acids include citric found in fruit juices like orange, lemon and grapefruit, hydrochloric, which is found in our stomachs, and acetylsalicylic, known as aspirin. Common bases include magnesium hydroxide, known as milk of magnesia, ammonia and bicarbonate of soda. A base neutralizes an acid when mixed. For instance, ingesting a base such as milk of magnesia or sodium bicarbonate neutralizes an excess of acid in our stomachs. When acids and bases are mixed, they produce salt and water.
  
  

The Scientific Angle

• The difference between an acid and a base, as theorized by a Swedish chemist Svante Arrhenius in 1887, is that an acid breaks down in water and produces a positive hydrogen ion (H+). A base breaks down in water and produces one or more hydroxide ions (OH-). How does one tell which is which? An acid will turn litmus paper red. A base will turn litmus paper blue.
  
  

Other Qualities

• Acids and bases both can cause burns, especially to skin. Both will conduct electricity because they form electrolytic solutions and release ions. Acids will react with metals, releasing hydrogen gas, whereas bases will not. Acids and bases are categorized as weak or strong. If they are strong, they dissolve completely in water; if they are weak, they only partially dissolve. Most acids and bases are considered weak. When mixed, a strong acid will overtake a weak base and vice versa.
  
  

Everyday Items

• With a pH ranging from 8 to 9, toothpaste is a base.Jupiterimages/liquidlibrary/Getty Images
  
  Examples of acids we come in contact with daily include sulphuric acid in acid rain, acetic acid in vinegar, uric acid in urine and tannic acid in wine and tea. Fresh milk with a pH of 6.5 is close to neutral, but sour milk, with a pH of 4.5, is decidedly acid. Most of your personal hygiene items, such as soap and toothpaste, are bases as are many cleaning agents, including bleach and ammonia.