Determination Of pH Of Some Solutions Obtained From Fruit Juices, Solution Of Known And Varied Concentrations Of Acids, Bases And Salts Using pH Paper Or Universal Indicator

Acids are substances that generate free hydrogen ions (H+ ions) when dissolved in water. Bases are substances when dissolved in water produces hydroxyl ions (OH- ions). Acidic solutions are rich in hydrogen ions and basic solutions are poor in hydrogen ions. Universal indicator is a pH indicator composed of different chemical compounds. Learn how to find whether the solution is an acid or base.

Aim:

Determination of pH of Solutions like fruit juices of different acids, bases, and salts using pH paper and universal indicator.

Materials Required:

pH paper, Universal indicator, sample solutions, test tubes, white tile and dropper

The Procedure of Determination of pH Using Universal Indicator:

  1. Take the given samples of fruit juices like lemon, orange, pineapple, and apple in a separate test tube.
  2. Make sure you have taken at least 2 mL of juices in each test tube.
  3. Use a separate dropper to transfer each juice sample into a test tube.
  4. Add two drops of universal indicator.
  5. Mix the content thoroughly by shaking it gently.
  6. Refer the pH chart to match the color that appears in the test tube. (match the color produced with standard color pH chart)
  7. Record your observation.

Precautions to be taken during the experiment:

  • Carefully match the color of the solution that appears with the standard color pH chart.
  • Add the equal quantity of indicator into the juice sample

Observation

Determination of pH Using Universal Indicator on different

sample

Color with pH indicator

pH

interference

Apple juice

Pineapple juice

Orange juice

Lemon juice

The Procedure of Determination of pH Using pH paper:

  1. On a white tile place a clean pH paper strip.
  2. Drop of the sample on the pH paper using a clean dropper.
  3. Observe the change in the color of the pH paper.
  4. Now compare the color obtained on the pH paper with the color shades on the standard pH chart.
  5. Make a note of the pH value obtained.

Precautions to be taken during the experiment:

  • Carefully match the color of the solution that appears with the standard color pH chart.
  • Keep the pH strips away from chemical fumes.
  • Keep the pH paper clean

Observation

Determination of pH Using pH paper

sample

Colour produced on the pH Paper

Approximate pH

Viva Voice:

  1. What is pH?

    pH is the value which is used representing the alkalinity or acidity of a solution on a logarithmic scale. pH is defined as the negative logarithm (base 10) of hydrogen ion concentration.

    Determination of pH of some solutions-viva-questions

  2. What is the pH of the solution if it is acidic?

    It is less than 7

  3. Which has lower pH value – apple juice or lemon juice?

    Since lemon juice is more acidic it has a lower pH value

  4. What is the pH of water at 25-degree Celsius?

    pH = 7

  5. What is the pH of distilled water?

    pH = 7