CBSE Class 10 Science (Chemistry) Practical Skills- pH of Samples

-
pH of Samples
The nature of the chemicals used in laboratories is either basic, acidic or neutral. This characteristic depends on the ions they release. A chemical is said to be acidic if it releases H+ ions in its aqueous solutions. A chemical is said to be basic if it releases OH– ions in its aqueous solutions. In this experiment, we will learn how to find the pH of acids and bases.
Table of Contents
*  Aim
* Materials required
* Theory
* Procedure
* Observation
* Result and Conclusion
* Precautions to be taken during the experiment
* Viva Voce

Aim:
To determine the pH of the given samples using pH paper or universal indicator. The samples whose pH has to be determined are-

(1) Dilute CH3COOH
(2) Dilute NaOH
(3) Salt NaCl
(4) Dilute NaHCO3
(5) Water
(6) Lemon juice

Materials required:
(1) Six test tubes
(2)Test tube stand
(3) Dilute acid CH3COOH
(4) Dilute base NaOH
(5) Salt NaCl (preparation: dissolve 1 gram salt in 10 mL distilled water)
(6) Water
(7) Lemon juice
(8) Dilute NaHCO3
(9) Glass rod
(10) Measuring cylinder (10 mL)
(11) Standard pH colour chart
(12) pH paper
(13) Glass rod
(14) Dropper
(15) Universal indicator

Theory:

What is pH?
pH is a measure of hydrogen ion concentration to determine the alkalinity or acidity of a solution.
If the pH value of a solution is less than 7 it is an acidic solution
If the pH value of a solution is greater than 7 it is a basic solution
If the pH value of a solution is equal to 7 it is a neutral solution

What is pH scale?
The pH scale consists of values which range from 0 (very acidic) to 14 (very alkaline). The numbers on the scale help to determine the hydrogen ion concentration.

What is pH paper?
pH paper can help us to know if a solution is basic, acidic or neutral. When the pH paper is dipped into a solution whose pH has to be determined, a colour will be developed. This colour is compared with the standard pH colour chart. Instead of pH paper, we can also use universal indicator paper or universal indicator solution.

What is universal indicator?
A universal indicator is a mix of pH indicator solutions that are designed to determine the pH of solutions over a wide range of values. Put a drop of solution on the universal pH indicator paper. The colour developed on the paper is matched with the standard pH colour chart.Okay 
 
👇नीचे जो चित्र देख रहे हो pH Value Chart का इसे तुम्हें file में colour pencils से बनाने पड़ेंगे।

pH Value Chart

🤵👇ये वाला भी drawing बनाना पड़ेगा 
EXPERIMENTAL SET-UP

👇 ये भी 😅☺️

Observation
Result and Conclusion:
Precautions to be taken during the experiment:
* Use freshly prepared test sample for the experiment.

* The fruit juice sample should also be fresh to get the proper pH values.

* Glass rod or dropper used for one sample should be washed thoroughly before using it for the other samples.

Viva Voce:

(1) Who was the first scientist to introduce pH?
Ans: Soren Peder Lauritz Sorensen a Danish chemist.

(2) Define the pH of a solution.
Ans: It is a measure of the basic or acidic power of a solution. It is a scale to measure the hydrogen ion concentration in the solution. Lower the hydrogen ion concentration higher is the pH.

(3(  What is the pH of pure water at 25 °C?
Ans: 7.

(4) There are two solutions with different pH values. Solution A has a pH value 6 and solution B has a pH value 5. Which solution is more acidic?
Ans: Solution B whose pH value is 5 is more acidic.

(5) If the pH value of a solution is 9 then what is its colour?
Ans: Light blue.
 

Comments

Post a Comment

Popular posts from this blog

Experiment to Verify Ohm's Law)

-
Image
Experiment to Verify Ohm's Law)      CHAPTER - 12  'ELECTRICITY'   (Experiment to Verify Ohm's Law)  ************************************ Dependence of Potential Difference Across a Resistor on the Current  Passing through it and determine its resistance.  Studying the dependence of potential difference (V) across a resistor on the current (I) passing through it and determine its resistance. Also plotting a graph between V and I Potential difference is defined as the work done to move a unit charge from one point to the other. The SI unit of potential difference is volt. Electromotive force is defined as the electric potential produced by either an electrochemical cell or by changing the magnetic field. Below is an experiment to study the dependence of the potential difference across a resistor with current-carrying I. Table of Contents: * Aim * Theory * Materials Required * Circuit Diagram * Procedure * Observation Table *...
Read more

Determination of Focal Length of Concave Mirror and Convex Lens

-
Image
Determination of Focal Length of Concave Mirror and Convex Lens Before getting started with the experiment, it is important to understand a few terms that are used in a concave mirror and convex lens: Centre of curvature: For a curved mirror, the centre of curvature, C can be defined as the centre of a hollow glass sphere of which a curved mirror is a part. Radius of curvature: For a curved mirror, the radius of curvature, R can be defined as the radius of the hollow glass sphere of a spherical mirror is part. Principal axis: Principal axis is defined as the imaginary line passing through the pole and centre of curvature of the spherical mirror. Principal focus: Principal focus is defined as a point at which the reflected rays meet or appear to meet for the spherical mirror.  For a concave mirror, the principal focus is in the front and  For a convex mirror, the principal focus is at the behind. Below is an experiment to determine the focal length of a concave m...
Read more

Tracing Path of a Ray of Light Passing Through a Glass Slab

-
Image
Tracing Path of a Ray of Light Passing Through a Glass Slab Refraction is the property of light due to which it bends its path while travelling from one medium to another. The law of refraction is also known as Snell’s law which states that the ratio of the sine of the angle of incidence to the sine of the angle of refraction is equal to constant. Below is an experiment to trace the path of a light ray passing through the rectangular glass slab. Table of Contents: Aim Theory Materials Required Procedure7 Ruay Diagram Observation Table Conclusion Precautions Sources of Error Viva Questions Aim To trace the path of a ray of light passing through a rectangular glass slab for different angles of incidence. Measure the angle of incidence, angle of refraction, and angle of emergence, and interpret the result. Theory What are the laws of refraction ? Following are the laws of refraction: (I) The incident ray, the normal at the point of incidence, and the refracted ray lie in the s...
Read more