Basics Of Mole Concept k1329

Basics

Of

BASICS OF MOLE CONCEPT - Parishkrit Jain

Let us try to understand the mole concept with a simple example: If you have ever visited in a bank then you might have observed that people working there have large number of coins of various denominations. As you can imagine, it would really be very tedious to count such large number of coins. Then how do these people count them? Well, the simple method is to weigh the coins. Sounds strange! But it is true. Think of simpler example related to your life. We use to have grains (wheat, rice, etc.) or sugar in our houses. Do we really count each and every grain or sugar particle? Surely no. We just weigh them. It is often convenient to do so, especially in the case of grains and sugar. Let us go back to our example of banks. A simple question may arise in your mind: Knowing the weight of some coins of given denomination how can be count the total number of coins? The method is indeed very interesting and requires some simple math. You know that a fixed number of coins (of same denomination) will have the same mass. Let us, for an example, think that 10, ₹ 5 coins weigh 50 grams then you can know the weight of a single coin easily. Yes, it would be 5 grams. Now they put some coins on a weighing machine which shows their weight to be 550 grams. Can you figure out the number of coins on the weighing machine? We have the following relation: Weight of 1 coin = 5 grams. Let, Therefore, So,

Weight of =

coins = 550 grams = 110 coins

Number of coins = 110

This was rather simple but using this simple concept scientists count the ‘number’ of atoms or molecules present in elements and compounds (i.e. from their mass). In fact this ‘number’ is referred to as mole. But a simple question may arise in your mind: What is the need of counting the number of atom or molecules? Well, let us answer this question for you. Consider a simple chemical reaction, involved in formation of water:

2H2 + O2 → 2H2O

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BASICS OF MOLE CONCEPT - Parishkrit Jain

You can observe from this equation that in a chemical equation the number of molecules or atoms taking part in the reaction is indicated. Here, 2 molecules of Hydrogen combine with a single molecule of Oxygen to form 2 molecules of water. Thus, a chemical reaction directly indicates the number of atoms taking part in the reaction. So, it is more convenient to refer to the quantity of a substance in of the number of atoms taking part in the reaction, rather than their masses. Chemists need the number of atoms and molecules while carrying out reactions, and for this they need to relate the mass in grams to the number. Thus, a mole is the chemist’s counting unit. It has the unit symbol mol. Now let us move back to our previous discussion to see how they relate mass in grams to the number. How do scientists count atoms and molecules? The answer is simple: by weighing them. Experimentally it has been found that if we weigh an element equal to its atomic mass in grams, then it contains 6.022 X 10 23 atoms of the element. Recall that mole is actually a number. For example, 1 dozen apples always means only and only 12 apples, irrespective of their shape and size. Similarly: 1 mole (of anything) = 6.022 X 1023 in number 1 mole of atoms = 6.022 X 1023 number of atoms 1 mole of molecules = 6.022 X 1023 number of molecules 1 mole of particles (atoms, molecules, ions) = 6.022 X 1023 number of particles From this discussion we have the following relation: Gram atomic mass (of anything) = 1 mole (of anything) = 6.022 X 1023 in number You can also observe the advantage of using mole rather than dozen or gross that mass of 1 mole of a particular substance is always fixed. It is always equal to the relative atomic mass or molecular mass in grams. What is this 6.022 X 1023 actually called? This 6.022 X 1023 is actually called the Avogadro number or Avogadro constant (represented by NA or NO) in honour of Italian scientist Amadeo Avogadro. How do we write the gram atomic mass of an element?

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BASICS OF MOLE CONCEPT - Parishkrit Jain

Before moving further let us first see what is gram atomic mass or molar mass. Mass of 1 mole of particles is called molar mass or gram atomic mass. To get it, we take the numerical value of the atomic mass and simply write gram (g) after that or in other words, we write the atomic mass but place ‘g’ instead of ‘u’. For example, atomic mass of hydrogen=1u. So, gram atomic mass of hydrogen = 1g. So, can you tell now what the gram atomic mass of Sodium is? ( that the atomic mass of Sodium is 23u). Yes, it is 23g. Now, we know that 1u of hydrogen has 1 atom of hydrogen. So, 1g of hydrogen has 1 mole of atoms that is 6.022 X 1023 atoms of Hydrogen. Let us consider one more example. 16u oxygen has only 1 atom of oxygen, 16 g oxygen has 1 mole atoms, that is, 6.022×1023 atoms of oxygen. Before moving on, there is a question for you: Question. What is the molar mass of water? Solution. Molecular formula of water is H2O. Now,

Atomic mass of Hydrogen = 1u Atomic mass of Oxygen = 16u

Therefore, Molecular mass of water = (2 X 1u) + 16u = 18u So,

Molar mass of water = 18g

What do you understand from this? 18u water has only 1 molecule of water, 18g water has 1 mole molecules of water, that is, 6.022×1023 molecules of water.

FACT

TO

K

NOW ???

The word “mole” was introduced around 1896 by Wilhelm Ostwald who derived the term from the Latin word moles meaning a „heap‟ or „pile‟. A substance may be considered as a heap of atoms or molecules. The unit mole was accepted in 1967 to provide a simple way of reporting a large number- the massive heap of atoms and molecules in a sample. Wilhelm Ostwald

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BASICS OF MOLE CONCEPT - Parishkrit Jain

The illustration given below shows the relationship between mole, Avogadro number and mass:

Let us now try to define the important we have learnt so far: ‘Mole is the amount of substance that contains the same number of particles.’ ‘1 mole of any species (atoms/molecules/ions/particles) is that quantity in number having a mass equal to its atomic mass or molecular mass in grams.’ We can define Avogadro constant 6.022X1023 as ‘the number of atoms in exactly 12 grams of Carbon-12.’

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BASICS OF MOLE CONCEPT - Parishkrit Jain

Solving Problems Related To Mole Concept. Before moving further we need to know the following symbols used while solving numerical problems: Number of moles Given mass Molar mass Given number of particles Avogadro number

=n =m =M =N = NO

Let us now suppose that we need to find number of moles (i.e. n) in a given mass (m) of element x, given that the molar mass of the element is M. Now,

Molar mass of x = 1 mole of element x

=

So,

KEY CONCEPT

=

Or, In other words,

=

Let us understand this relation with a simple example: Sample Problem 1. Calculate the number of mole in 52 g of Helium. Solution. We know that, Atomic mass of He = 4u So, its molar mass = 4 g That is, 4 g of He contains 1 mole of He. Or, 4 g of He = 1 mole of He So, 52 grams of Helium =

X 52 mole

= 13 moles Therefore, there are 13 moles in 52 g of He.

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BASICS OF MOLE CONCEPT - Parishkrit Jain

From the 5th step of this example you could have easily observed that 52 grams (i.e. given mass) of Helium contains

number of moles. Thus, we

our relationship. Now, Let us try to find number of moles (i.e. n) for given number of particles (N) of an element x. We know that, 1 mole (of anything) = 6.022 X 1023 in number i.e., 1 mole of x = NO

=

=>

KEY CONCEPT

=

=>

In other words,

=

Now let us look at some sample problems to illustrate the use of above formulas. Sample Problem 2. Calculate the number of moles for 12.044 X 1023 atoms of Helium. Solution. We know that,

= Or,

=

= =2 Therefore, there are 2 moles in 12.044 X 1023 atoms of He.

Before moving further we have got a simple exercise for you to let you apply the concepts you have learned so far.

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BASICS OF MOLE CONCEPT - Parishkrit Jain

WHAT HAVE YOU LEARNT? 1. In 1896, William Ostwald, introduced a term mole which can be defined as…………………………...........……………..……………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… 2. What do the following symbols mean? n …………………………………………………… N ………………………………………………….. M …………………………………………………. M …………………………………………………. 3. The Avogadro constant is ………………………………….. and is represented as ………… 4. How many moles are there in 5 grams of calcium? ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ………………………………………………………………………………………………

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BASICS OF MOLE CONCEPT - Parishkrit Jain

……………………………………………………………………………………………… ………………………………………………………………………………………………

……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… 5. How many moles there in 12.044 X 1023 atoms of phosphorous? ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ………………………………………………………………………………………………

……………………………………………………………………………………………… ………………………………………………………………………………………………

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BASICS OF MOLE CONCEPT - Parishkrit Jain

So, far we have learned the following important relations:

= =

and,

So, we can now easily find the number of moles in a given mass of element or given number of particles. But have you ever thought how can we find the mass of an element or the number of particles of an element that contains given number of moles? That’s rather simple! In fact, we can do so and many other related things using just these basic key concepts. Let us do so. Suppose we need to find mass of an element x that contains given mole of atoms.

=

We know that, Or,

=

Or, Or, Mass = Number of moles X Molar mass. Let us now suppose that we need to find number of particles (N) of an element in a given mole of atoms. We know that,

= Or,

=

Or, Or, Number of particles = Number of moles X Avogadro number. Can you find the mass (m) of an element if the number of particles (N) is known? Or, can you find the number of particles (N) in a given mass (m) of an element?

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BASICS OF MOLE CONCEPT - Parishkrit Jain

Let us now suppose that we need to determine mass (m) of an element when the number of particles (N) is known.

=

We have, Or,

=

We also know that, Or,

………...……………… (i) Mass = Number of moles X Molar mass.

m=MXn

Substituting for n from (i), We get,

m=MX

... Mass = Let us now suppose that we need to determine the number of atoms (N) in a given mass (m) of an element.

=

We have, Or,

=

We also know that,

………...……………… (i) Number of particles = Number of moles X Avogadro number.

Or, Substituting for n from (i), We get,

N=

... Number of particles =

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BASICS OF MOLE CONCEPT - Parishkrit Jain

So, we a seen a lot many number of derivations from two simple key formulas. Let us now look at all of them for once. a) Mass = Number of moles X Molar mass b) Number of particles = Number of moles X Avogadro number c) Mass = d) Number of particles = The following sample problems illustrate the use of all these formulas. Sample Problem 3. Calculate the mass of 0.5 mole of Nitrogen atoms. Solution. We know that, Mass = Number of moles X Molar mass Or, = 0.5 X 14 =7g Therefore, mass of 0.5 mole of N atoms is 7 grams. Sample Problem 4. What is the mass of 3.011 X 1023 number of Nitrogen atoms? Solution. We know that, Mass = Or,

m=MX = 14 X =7g

Therefore, mass of 3.011 X 1023 number of N atoms is 7 grams.

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BASICS OF MOLE CONCEPT - Parishkrit Jain

Sample Problem 5. Calculate the number of particles in each of the following: (i) 0.1 mole of Carbon atoms (ii) 46 grams of Sodium atoms. Solution. (i) We know that, Number of particles = Number of moles X Avogadro number Or, = 0.1 X 6.022 x 1023 = 6.022 X 1022 Therefore, 0.1 mole of C atoms have 6.022 X 1022 number of atoms. (ii) We know that, Number of particles = Or,

N= =

X

= 12.044 X 1023 Therefore, 46 g of Na atoms have 12.044 X 1023 number of atoms. Thus we see the application of concepts we have learned in the chapter. Now we have got some exercises for you to work on and learn the things with ease. But before that, let us revise the key formulas once again:

= and,

=

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BASICS OF MOLE CONCEPT - Parishkrit Jain

WHAT HAVE YOU LEARNT? 1. One mole of any species is that quantity in number ………………………….…………………………...........……………..……………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… 2. State the formulas to find the number of atoms in a given mole and in a given mass of elements. Formula 1 ……………………………………………………….....………………… ……………………………………………………….....………………………………….

Formula 2…………………………………….………………………………………… ………….....……………………………..……………………………………………….. 3. What is the mass of 4 moles of Aluminum atoms? ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ………………………………………………………………………………………………

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BASICS OF MOLE CONCEPT - Parishkrit Jain

4. Determine the number of iron atoms in a piece of iron weighing 2.8 grams. ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… 5. If one mole of Carbon atoms weigh 12 grams, what is mass in grams of a single atom of Carbon? ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… …………………………………………………………………………….…………………

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BASICS OF MOLE CONCEPT - Parishkrit Jain

Here we go looking at some more sample questions to get a better understanding of the text. Sample Problem 6. Calculate the mass of 0.5 mole of N2 gas. Solution. We know that, Mass = Number of moles X Molar mass Or, = 0.5 X (14+14) = 14 g Therefore, mass of 0.5 mole of N2 atoms is 14 grams. Sample Problem 7. Convert 12.044 X 1022 molecules of Sulphur dioxide into moles? Solution. We know that, Number of moles = Or,

n= = = 0.2

Therefore, 12.044 X 1022 molecules of SO2 contains 0.2 mole. Sample Problem 8. In which case the number of Hydrogen atoms is more- 2 mol of HCl or 1 mol of NH3? Solution. We know that, HCl contains 2 moles of H atoms. Also, NH3 contains 3 moles of H atoms. Therefore, 1 mole of NH3 contains more number of atoms.

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BASICS OF MOLE CONCEPT - Parishkrit Jain

Sample Problem 9. An ornament of silver contains 20 gram silver. Calculate the moles of silver present. Solution. We know that,

= Or,

=

= = 0.185 Therefore, there are 0.185 mol in 20 g of Ag.

Sample Problem 10. If 1 g sulphur dioxide contains x molecules, what will be the number of molecules in 1 g of methane? Solution. We have, 1 mol of SO2 = 32 + (16 X 2) = 64 gram ... 1 g of SO2 = Now, ...

mole

mole of SO2 contains x molecules. mole of methane also contain x molecules.

Now, 1 mol of CH4 = 12 + (4 X 1) = 16 gram ... 1 g of CH4 = But ...

mole

mole of methane = x molecules. mole of CH4 =

molecules

= 4x molecules ... If 1 g of SO2 contains x molecules, then 1 g of CH4 contains 4x molecules. And now the time comes for you to test yourself.

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BASICS OF MOLE CONCEPT - Parishkrit Jain

WHAT HAVE YOU LEARNT? 1. One mole of oxygen atoms = ………………………….…… oxygen atoms in number

2. Choose the correct option in the following: Which of the following has maximum number of molecules? (a) 4 g of H2 gas

(b) 1 mole of H2O gas

(c) 3 mole of CO

(d) 22 g of CO 2

3. Choose the correct option in the following: What is the number of Sulphur atoms in one mole of S8? (a) 4.818 X 1024

(b) 4.121 X 1024

(c) 4.022 X 1023

(d) 4.284 X 1022

4. Calculate the number of aluminium ions present in 0.051 g of aluminium oxide. ……………………………………………………………………………………………... ……………………………………………………………………………………………... ……………………………………………………………………………………………... ……………………………………………………………………………………………... ……………………………………………………………………………………………...

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BASICS OF MOLE CONCEPT - Parishkrit Jain

5. How many grams of neon will have the same number of atoms as 4 g of calcium? ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ………………………………………………………………………………………………

……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… 6. Calculate the number of iron atoms in a piece of iron weighing 2.8 grams. ………………………………………………………………………………………………

……………………………………………………………………………………………… ……………………………………………………………………………………………… ………………………………………………………………………………………………

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BASICS OF MOLE CONCEPT - Parishkrit Jain

7. What is the mass of 3 moles of Zinc? ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… 8. What is the ratio of molecules present in 6.6 grams of CO 2 and 3.2 grams of SO2? ………………………………………………………………………………………………

……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ………………………………………………………………………………………………

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BASICS OF MOLE CONCEPT - Parishkrit Jain

And that is it! Now, we are in a position to solve a self-evaluation test. It is a question paper of 50 marks to be solved in 1 hour and contains 20 questions. All the questions are related to what we have learned in this chapter. It would be like an exam-type test. It is advised to give the test only after completing the text and reading the summary given at the end. In this test, as the name suggests, you are going to test yourself. If your score is less than half the total score (i.e. less than 25), then you must attempt the practice questions given below. to go through these practice questions also. PRACTISE QUESTIONS

1. Determine the mass of 6.022 X 1023 number of N2 molecules. 2. Calculate the number of particles in(i) 8 g of O2 molecules (ii) 2.5 mol of calcium atoms. 3. What is the mass of 2.5 mol of Methane? 4. Find the mass of one molecule of water. 5. Calculate the number of water molecules and number of oxygen and hydrogen atoms in a drop of water containing 0.03 mol of water. 6. Calculate the actual mass of one atom of carbon if 12 grams of Carbon contain one mole of Carbon. 7. Calculate mass of Nitrogen (N2) which contains same number of molecules as are present in 4.4 grams of Carbon-di-oxide (CO2). 8. Atomic mass of gold is 197 u. How many moles of gold are present in an ornament containing 88.65 grams of gold? 9. How many moles of SO2 have same mass as 3 moles of oxygen? 10. A glass of water contains 5 mol of water. How many molecules of water are present? 11. What is the mass of a formula unit of Na+Cl-? 12. How many atoms of Silver are present in a silver wire weighing 5.4 grams? 13. Calculate the ratio of molecules present in 16 g of methane and 16 g of oxygen. 14. Convert into mole. (a) 12 g of oxygen gas (b) 20 g of water (c) 22 g of carbon-dioxide. 15. Determine the number of bromide ion in 0.2 mole of MgBr2.

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BASICS OF MOLE CONCEPT - Parishkrit Jain

Series MOLE/1

Code No. 13/15/12/5

Name

 This is a self-evaluation test and is to be solved only after understanding the concepts mentioned in the text.  This question-paper contains questions regarding the concepts learned in the text.  Please check that this question paper contains 20 questions.  Please write down the serial number of the question paper before attempting it.  15 minutes time has been allotted to read this question paper.  It is required to fill candidate’s name in the space provided in this question paper.  The question paper should be completed within the prescribed time limit.  While answering this question paper avoid referring to any text.  Before writing the answers please read the instructions carefully.  Be honest while evaluating yourself.

SELF-EVALUATION TEST BASICS OF MOLE CONCEPT Time allowed: 1.15 hour]

[Maximum marks: 45

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BASICS OF MOLE CONCEPT - Parishkrit Jain

General Instructions: (i)

The question paper comprises of two sections, A and B. You are to attempt both the sections.

(ii)

All questions are compulsory.

(iii)

There is no overall choice. However, internal choice has been provided in the last question of five marks category. Only one option in this question is to be attempted.

(iv)

All questions in Section A and all questions of Section B are to be attempted separately.

(v)

Question numbers 1 to 10 in Section A are MCQs. Of these, question numbers 1 to 5 carry 1 mark each and question numbers 6 to 10 carry two marks each.

(vi)

Question numbers 11 and 12 in Section B are short answer type questions of two marks each. The answer to these questions should not exceed 30 words.

(vii) Question numbers 13 to 18 in Section B are also short answer type questions but carry 3 marks each. (viii) Question number 19 is a age-based question and has 3 sub-questions which are very short answer type and carry 1 mark each. (ix)

Question number 20 in Section B is a long answer type question and carries five marks.

(x)

There is no negative marking for the questions of Section B. However for each wrong answer in Section A, 1 mark will be deducted.

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BASICS OF MOLE CONCEPT - Parishkrit Jain

SECTION A 1. Which one of the following statements is true regarding Sodium? a) 1 g Sodium has 1 mole atoms b) 1 g Sodium has 6.022 X 1023 atoms c) 23 g Sodium has 1 mole of atoms d) 23 g Sodium has 6.022 X 1022 atoms 2. The molar mas of Chloroform (CHCl3) isa) 119.5 grams b) 118 grams c) 49 grams d) 50.5 grams 3. Which of the following correctly represents 360 g of water: (i) 2 moles of H2O (ii) 20 moles of water 23 (iii) 6.022 × 10 molecules of water (iv) 1.2044×1025 molecules of water a) (i) only b) (i) and (iv) c) (ii) and (iii) d) (ii) and (iv) 4. Mass of one atoms of Oxygen is a)

grams

b)

grams

c)

grams

d) 8 u 5. Avogadro constant is called so in whose honour? a) Wilhelm Ostwald b) Amadeo Avogadro

P.T.O .

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BASICS OF MOLE CONCEPT - Parishkrit Jain

c) Wilhelm Avogadro d) Amadeo Ostwald 6. Which of the following would weigh the highest? a) 0.2 mole of sucrose (C12 H22 O11) b) 2 moles of CO2 c) 2 moles of CaCO3 d) 10 moles of H2O 7. Which of the following has maximum number of atoms? a) 18 grams of H2O b) 18 gram of O2 c) 18 gram of CO2 d) 18 grams of CH4 8. 3.42 g of sucrose are dissolved in 18 g of water in a beaker. The number of oxygen atoms in the solution area) 6.68 × 1023 b) 6.09 × 1022 c) 6.022 × 1023 d) 6.022 × 1021 9. Which of the following contains maximum number of molecules? a) 1g CO2 b) 1g N2 c) 1g H2 d) 1g CH4 10. For the given reaction, H2O + Cl2 + H2S H2SO4 + HCl, the correct statement is: a) The mole ratio between Cl2 and H2S is 2:1 in balanced reaction b) The mole ratio between H2O and H2S is 4:1 in balanced reaction c) 1 mole of H2SO4 is produced from 2 moles of Cl2 d) 4 moles of H2O are required to produce 4 moles of HCl

P.T.O .

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BASICS OF MOLE CONCEPT - Parishkrit Jain

SECTION B 11. In a Science laboratory, there are two samples as follows: SAMPLE A – 2 grams of Hydrogen gas SAMPLE B – 2 grams of Helium gas Find a relation between the number of moles of the given two samples. 12. Scientists use a unit called ‘mole’ to count the number of atoms or molecules. Why don’t they use any other unit like, dozen or gross, to count the number of particles? 13. In the formation of CO, it is found that 2.445 g of carbon combines with 3.260 g of oxygen. What is the atomic ratio of carbon and oxygen which combine? 14. Calculate number of atoms in 120 gram of Calcium and 120 gram of Iron. Which one has more number of atoms and how much is the difference? (Given atomic mass of Calcium = 40 u, Iron = 56 u) 15. If one gram of Sulphur contains x atoms, what will be the number of atoms in one gram of oxygen? (atomic mass of S = 32u) 16. Calcium chloride when dissolved in water dissociates into its ions according to the following equation. CaCl2 (aq) → Ca2+ (aq) + 2Cl– (aq) Calculate the number of ions obtained from CaCl2 when 222 g of it is dissolved in water. 17. The mass of one steel screw is 4.11 g. Find the mass of one mole of these steel screws. Compare this value with the mass of the Earth (5.98 × 10 24 kg). Which one of the two is heavier and by how many times? 18. A currency counting machine counts 6 lakh notes per day. A bank has as many notes as number of Hydrogen atoms in 24.8 grams of Na2S2O3.5H2O. How many days would be required to count these notes? Give an approximate answer in of power of ten. 19. Read the following age carefully and answer the questions that follow: Moles measure quantity of substance. There is a subtle ambiguity about treating “moles” – whether as “mass” or “number”. We take the position that it measures “amount of substance”, which can be either be expressed in of mass or in of numbers. The two approaches are equivalent and need not be a source of ambiguity any further. We only need to interpret the meaning as appropriate in a particular context.

P.T.O .

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BASICS OF MOLE CONCEPT - Parishkrit Jain

a) How is mole related to ‘mass’? b) How is mole related to ‘number’? c) What does mole actually measure? 20. A sample of ethane (C2H6) gas has the same mass as 1.5 × 1020 molecules of methane (CH4). How many C2H6 molecules does the sample of gas contain? OR In photosynthesis, 6 molecules of carbon dioxide combine with an equal number of water molecules through a complex series of reactions to give a molecule of glucose having a molecular formula C6H12O6. How many grams of water would be required to produce 18 g of glucose? Compute the volume of water so consumed assuming the density of water to be 1 g cm–3.

*****

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BASICS OF MOLE CONCEPT - Parishkrit Jain

Series MOLE/1

Code No. 13/15/12/5

SOLUTION TO SELF-EVALUATION TEST BASICS OF MOLE CONCEPT SECTION A 1. c) 2. a) 3. d) 4. a) 5. b) 6. c) 7. d) 8. a) 9. c) 10. b)

SECTION B 11. Number of moles of Sample A (Hydrogen) is double that of Sample B (Helium). 12. Relative advantage of using mole is that not only number but also mass of 1 mole of a particular substance is always fixed. 13. 1:1 14. Calcium- 1.8066 X 1024; Iron- 1.2904 X 1024 ; Calcium has 5.162 X 1023 more atoms 15. 2x atoms 16. 3.6 132 X 1024 ions 17. Mass of 1 mole of steel screws- 2.475 X 1021 kg; Earth is 2400 times heavier.

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BASICS OF MOLE CONCEPT - Parishkrit Jain

18. 1018 days 19. a) Mass of 1 mole of a substance is fixed and equals molar mass of the substance. b) 1 mole of a substance always contain Avogadro number of particles. c) Amount of substance- either in of mass or number 20. 0.8 X 1020 molecules OR 10.8 grams; Volume- 10.8 cm3.

*****

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BASICS OF MOLE CONCEPT - Parishkrit Jain

Summary of Mole Concept.  The Avogadro constant, 6.022 X 1023 is defined as the number of atoms in exactly 12 g of Carbon.  Mole is the amount of substance that contains the same number of particles (atoms / ions / molecules/ formula units etc.).  1 mole of any species (atoms / ions / molecules/ particles) is that quantity in number having a mass equal to its atomic mass molecular mass in grams.  Mass of 1 mole of a substance is called its molar mass.  Number of moles = n Given mass = m Molar mass = M Given number of particles = N Avogadro number = NO  Key formulai)

=

ii)

=

 Other formulaiii)

Mass = Number of moles X Molar mass

iv)

Number of particles = Number of moles X Avogadro number

v)

Mass =

vi)

Number of particles =

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BASICS OF MOLE CONCEPT - Parishkrit Jain

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