Acids, Bases and Salts

pH

We often hear that certain substances are acidic or basic in nature. But how does one find out whether the substance is acidic, basic or neutral? What makes the substance acidic or basic? All these things are determined with the help of a pH scale. Let us educate ourselves about this scale of measurement.

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What is pH?

pH is a numeric scale in chemistry that is used to determine whether the substance is acidic, basic or neutral in nature. Substances that have a pH level of less than 7 are acidic in nature. For e.g Acidic substances such as vinegar, tamarind, lemon, etc. Substances that have a level of more than 7 are basic in nature. For e.g. Basic substances such as baking soda, limewater, ammonia, etc. Whereas substances which have a pH value of 7 are neither basic nor acidic which means they’re neutral in nature. For e.g. Pure water. pH stands for potential of Hydrogen. The level of extremely strong acids can be less than 0 and the level of extremely strong bases can be more than 14.

Learn more about Acids and Bases here.

These measurements are essential in biology, chemistry, civil engineering, water purification, agriculture, forestry, food science, Environmental science, water treatment, oceanography, medicine, nutrition, agronomy, etc. This concept was developed by Søren Peder Lauritz Sørensen, a Danish chemist at the Carlsberg Laboratory in the year 1909 and revised to its modern standards in the year 1924.

pH Indicators

pH indicators are indicators that show the pH value of substances, they change color over the small range of the scale. Some common indicators are litmus paper, phenolphthalein, Methyl orange, bromothymol blue, etc. The indicator is a chemical detector used to detect the hydrogen ions (H+) and hydroxyl ions (OH-) in a solution. Olfactory indicators can change their odor. Some examples of olfactory indicators are onion, vanilla extract, clove oil, etc.

pH value of things in daily routine

  • Apples – 3 (Acidic)
  • Bananas – 4 (Acidic)
  • Butter – 6 (Acidic)
  • Water – 7 (Neutral)
  • Borax – 9 (Basic)
  • Lime water – 12 (Basic)
  • Milk – 6 (Acidic)
  • Vinegar – 2 (Acidic)
  • Baking soda – 9 (Basic)
  • Eggs – 8 (Basic)
  • Black Coffee – 5 (Acidic)
  • Tomato Juice – 4 (Acidic)
  • Chocolate – 5 (Acidic)
  • Rice – 6 (Acidic)
  • Shampoo – Usually between 5 – 7 (Acidic or neutral)
  • Honey – 4 – 6 (Acidic)
  • Mango – 6 (Acidic)
  • Sugar – 7 (Neutral)
  • Carrot – 6 (Acidic)
  • Potatoes – 5 – 6 (Acidic)

Learn more about the concept of Neutralization here.

Solved Example for You :

Q: What is the pH value of seawater? Is it acidic, basic or neutral in nature?

  1. less than two, it is highly acidic
  2. more than ten, it is highly basic
  3. between 7 – 8.5, it is neutral or slightly basic
  4. between 5.5. – 7, it is neutral or slightly acidic

Ans. The correct answer is option ‘b’. The value of seawater is between 7 to 8.4. Ideally, the sea water is neutral or slightly basic.

Q: What is the pH level of the human body? Is it acidic, basic or neutral?

  1.  Less than 7, acidic
  2. 7, Neutral
  3. More than 7, basic
  4. None of the above

Ans: The pH value of a normal body is ideally 7.4 which is on the alkaline side of neutral and human blood is usually between 7.35 to 7.45 and of human saliva is 7.5.

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