Course Content
CHAPTER 3: CLASSIFICATION OF ELEMENTS
Section Name Topic Name 3 Classification of Elements and Periodicity in Properties 3.1 Why do we Need to Classify Elements ? 3.2 Genesis of Periodic Classification 3.3 Modern Periodic Law and the present form of the Periodic Table 3.4 Nomenclature of Elements with Atomic Numbers > 100 3.5 Electronic Configurations of Elements and the Periodic Table 3.6 Electronic Configurations and Types of Elements: s-, p-, d-, f – Blocks 3.7 Periodic Trends in Properties of Elements
0/6
CHAPTER 7: EQUILIBRIUM
Section Name Topic Name 7 Equilibrium 7.1 Equilibrium in Physical Processes 7.2 Equilibrium in Chemical Processes – Dynamic Equilibrium 7.3 Law of Chemical Equilibrium and Equilibrium Constant 7.4 Homogeneous Equilibria 7.5 Heterogeneous Equilibria 7.6 Applications of Equilibrium Constants 7.7 Relationship between Equilibrium Constant K, Reaction Quotient Q and Gibbs Energy G 7.8 Factors Affecting Equilibria 7.9 Ionic Equilibrium in Solution 7.10 Acids, Bases and Salts 7.11 Ionization of Acids and Bases 7.12 Buffer Solutions 7.13 Solubility Equilibria of Sparingly Soluble Salts
0/7
CHAPTER 10: S-BLOCK ELEMENTS
Section Name Topic Name 10 The s-Block Elements 10.1 Group 1 Elements: Alkali Metals 10.2 General Characteristics of the Compounds of the Alkali Metals 10.3 Anomalous Properties of Lithium 10.4 Some Important Compounds of Sodium 10.5 Biological Importance of Sodium and Potassium 10.6 Group 2 Elements : Alkaline Earth Metals 10.7 General Characteristics of Compounds of the Alkaline Earth Metals 10.8 Anomalous Behaviour of Beryllium 10.9 Some Important Compounds of Calcium 10.10 Biological Importance of Magnesium and Calcium
0/7
CHAPTER 12: CHARACTERIZATION OF ORGANIC COMPOUND
Section Name Topic Name 12 Organic Chemistry – Some Basic Principles and Techniques 12.1 General Introduction 12.2 Tetravalence of Carbon: Shapes of Organic Compounds 12.3 Structural Representations of Organic Compounds 12.4 Classification of Organic Compounds 12.5 Nomenclature of Organic Compounds 12.6 Isomerism 12.7 Fundamental Concepts in Organic Reaction Mechanism 12.8 Methods of Purification of Organic Compounds 12.9 Qualitative Analysis of Organic Compounds 12.10 Quantitative Analysis
0/13
Class 11th Chemistry Online Class For 100% Result
About Lesson

Precision & Accuracy

  • Every experimental measurement has some amount of uncertainty associated with it. Everyone wants the results to be precise and accurate. Precision and Accuracy are often referred to whenever we talk about measurement.
  • Precision refers to the closeness of various measurements for the same quantity. It does not depend on true value.
  • Accuracy is the agreement of a particular value to the true value of the result. It depends on the true value.

Significant figures

  • The uncertainty in the experimental or the calculated values is indicated by mentioning the number of significant figures.
  • Significant figures are meaningful digits which are known with certainty.
  • There are certain rules for determining the number of significant figures. They are as follows:
  1. All non-zero digits are significant. For example: – There are 4 significant figures in 328.2 cm.
  1. Zeros preceding to first non-zero digit are not significant. For example: – 0.03 has one significant figure and 0.0052 has two significant figures.
  1. Zeros between two non-zero digits are significant. For example: – 2.005 have four significant figures.
  1. Zeros at the end or right of a number are significant provided they are on the right side of the decimal point. For example: – 200 g has three significant figures. But, if otherwise, the zeros are not significant. For example, 100 have only one significant figure.
  1. Exact numbers have an infinite number of significant figures. For example:- In 2 balls or 20 eggs, there are infinite significant figures as these are exact numbers and can be represented by writing infinite number of zeros after placing a decimal i.e.,2 = 2.000000 or 20 = 20.000000.

Addition & Subtraction

  • The result cannot have more digits to the right of the decimal point than either of the original numbers. For example: – (12.11 + 18.0+ 1.012) = 31.122. As 18.0 have only one digit after the decimal point therefore the result will be 31.1, one digit after the decimal point.

Multiplication & Division

  • In these operations, the result must be reported with no more significant figures as are there in the measurement with the few significant figures. For example: – 2.5×1.25 = 3.125. Answer will be 3.1 because 2.5 have two significant figures and the result should not have more than two significant figures.

Dimensional Analysis

  • When calculating, there is a need to convert units from one system to other.
  • The method used to accomplish this is called factor label method or unit factor method or dimensional analysis. For example: – A jug contains 2L of milk. Calculate the volume of the milk in m3.

Problem:-

How many significant figures are present in the following?

(i) 0.0025

(ii) 208

(iii) 5005

(iv) 126,000

(v) 500.0

(vi) 2.0034

Answer:-

(i) 0.0025

There are 2 significant figures.

(ii) 208

There are 3 significant figures.

(iii) 5005

There are 4 significant figures.

(iv) 126,000

There are 3 significant figures.

(v) 500.0

There are 4 significant figures.

(vi) 2.0034

There are 5 significant figures.

Problem:-

Round up the following upto three significant figures:

(i) 34.216

(ii) 10.4107

(iii) 0.04597

(iv) 2808

Answer:-

(i) 34.2

(ii) 10.4

(iii) 0.0460

(iv) 2810

Problem:-

A jug contains 2L of milk. Calculate the volume of the milk in m3.

Answer:-

Since 1 L = 1000 cmand 1m = 100 cm which gives

 (1 m)/ (100 cm) = 1 = (100 cm/1m)

To get m3 from the above unit factors, the first unit factor is taken and it is cubed.

Therefore, (1m) 3 / (100cm) 3 =1 = (1m3)/ (106 cm3) (unit factor)

Now 2 L of milk = 2×1000 cm3

The above is multiplied by the unit factor

= 2 x1000 cm3 x (1 m3/106 cm3)

= 2 x 10-3 m3

Question 16. [NCERT Excercise]
What do you mean by significant figures?
Solution.
Significant figures : The significant figures in a number are all the certain digits plus one doubtful digit, e.g., 2005 has four significant figures.

Question 19.[NCERT Excersice]
How many significant figures are present in the following?
(i) 0.0025
(ii) 208
(iii) 5005
(iv) 126,000
(v) 500.0
(vi) 2.0034
Solution.
(i) 2
(ii) 3
(iii) 4
(iv) 3
(v) 4
(vi) 5

Question 20. [NCERT Excersice]
Round up the following upto three significant figures:
(i) 34.216
(ii) 10.4107
(iii) 0.04597
(iv) 2808
Solution.
(i) 34.2
(ii) 10.4
(iii) 0.0460
(iv) 2810 or 2.81 x 103

Q. Round off up to 3 significant figures (a) 1.235  (b) 1.225

Ans. (a) 1.24  (b) 1.22

Q. State the number of significant figures in each of the following

(i) 208.91  (ii) 0.00456  (iii) 453  (iv) 0.346

Ans.

(i) 208.91 has five significant figures.

(ii) 0.00456 has three significant.

(iii) 453 has three significant figures.

(iv) 0.346 has three significant figures.

Q. Express the results of the following calculations to the appropriate number of significant figures.

(i) (3.24 x 0.08666) / 5.006   (ii) (1.36 x 10-4 ) (0.5)/2.6

Ans.

(i) 0.05608 = 0.0561

(ii) 0.2615 x 10-4 = 0.3 x 10-4

Exercise Files
No Attachment Found
No Attachment Found
Wisdom Academy