Ncert Solutions Chemistry Class 12th

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Given -

Molarity, C = 0.00241 M

Conductivity, κ = 7.896 * 10^–5 S cm^–1

Molar conductivity? _m =?

? ⁰_mfor acetic acid = 390.5 S cm²mol^–1

Molar conductivity? _m = k/c X 1000 S cm² mol^-1

= 7.896 X 10^–5 S cm^–1X 1000 cm³ L^-1 / 0.00241 mol L^-1

∴? _m = 32.76 S cm² mol^-1

To calculate the dissociation constant, K_a, we use

K_a = → Equation 1

Here, we need to find the value of α (degree of dissociation), by the formula,

The molar conductivity? _m is 32.76 S cm² mol^-1 and the dissociation constant, K_a is 1.86*10^-5

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14.10 What are reducing sugars?

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Ncert Solutions Chemistry Class 12th Electrochemistry

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14.10

All those carbohydrates which reduce Fehling's solution to red precipitate of Cu₂O or Tollen's reagent to metallic Ag is called reducing sugars. All monosaccharides (both aldoses and ketoses) and disaccharides except Sucrose are reducing sugars.

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3.25 The conductivity of sodium chloride at 298 K has been determined at different concentrations and the results are given below: Concentration/M 0.001 0.010 0.020 0.050 0.100 102 * κ/S m^–1 1.237 11.85 23.15 55.53 106.74 Calculate Λm for all concentrations and draw a plot between Λm and c½ . Find the value of 0 Λm

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? ⁰ R = Intercept on the? axis = 124.0 S cm² mol^-1, which is obtained by extrapolation to zero concentration.

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14.9 What are monosaccharides?

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Ncert Solutions Chemistry Class 12th Electrochemistry

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14.9

Monosaccharides are the only the simplest units of carbohydrates and they are the simplest form of sugar. In other words, It is the most basic form of carbohydrates. They are made up of hydrogen, carbon and oxygen atoms. They are the building blocks of more complex carbohydrates i.e., they can join together and form complex carbohydrates.

For example:

i. Monosaccharides form

ii. 3-10 of them form

iii. 11 or more of them form

Monosaccharides are used to produce and store energy. Most organisms create energy by breaking down the monosaccharide glucose and harvesting the energy released from the bonds. Other Monosaccharides are

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3.24 The resistance of a conductivity cell containing 0.001M KCl solution at 298 K is 1500 ?. What is the cell constant if conductivity of 0.001M KCl solution at 298 K is 0.146 * 10^–3 S cm^–1 .

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Ncert Solutions Chemistry Class 12th Electrochemistry

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Given -
Resistance of a conductivity cell, R = 1500 Ω
Electrolytic conductivity of a solution, κ = 0.146 * 10^-3 S cm^-1
Cell constant =?
Conductivity, κ = cell constant/resistance
Cell constant = κ * R
= 0.146 * 10^-3 S cm^-1*1500 Ω
Cell constant = 0.219 cm^-1
The cell constant of the cell containing 0.001M KCl solution at 298 K is 0.219 cm^-1

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3.23 The conductivity of 0.20 M solution of KCl at 298 K is 0.0248 S cm^–1. Calculate its molar conductivity

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Given -
Molarity, C = 0.20 M
Electrolytic conductivity of a solution, κ = 0.0248 S cm^-1
Molar conductivity =?
Molar conductivity, ∧_m = K/C X 1000 S cm² mol^-1
=0.0248S cm^-1 X 1000 Cm³L^-1 / 0.20 mol L^-1

∴ ∧_m = 124 S cm² mol^-1
Molar conductivity (∧_m) of 0.20 M solution of KCl at 298 K is 124 S cm² mol^-1

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14.8 When RNA is hydrolysed, there is no relationship among the quantities of different bases obtained. What does this fact suggest about the structure of RNA?

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Ncert Solutions Chemistry Class 12th Electrochemistry

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14.8

A DNA is a double-stranded molecule (two polynucleotide chains whose nitrogenous bases are connected by hydrogen bonds).

In this molecule pairing or connection of bases occurs. Adenine always pairs with thymine, while cytosine always pairs with guanine.

So when DNA is hydrolyzed the amount of adenine produced is exactly equal to the amount of thymine produced, similarly, the amount of cytosine produced is equal to that of guanine.

But as given when RNA is hydrolyzed, there is no relationship between the quantities of different bases obtained. This suggests that RNA is a single-stranded molecule.

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3.22 Define conductivity and molar conductivity for the solution of an electrolyte. Discuss their variation with concentration.

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The conductivity of a solution is defined as the conductance of one unit volume of solution kept between two platinum electrodes with a unit area of cross-section and at a distance of unit length.The molar conductivity of the solution is defined as the conducting power of all the ions produced by
one gram mole of an electrolyte in a solution. It is denoted by ∧m.

The conductivity of a solution (both for strong and weak electrolytes) always decreases with the decrease in concentration of the electrolyte i.e., on dilution. This pattern is seen because the number of ions per unit volume that carry the current in the solution d

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14.7 What products would be formed when a nucleotide from DNA containing thymine is hydrolysed?

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14.7

When a nucleotide from DNA containing thymine is hydrolyzed β-D-2 deoxyribose and phosphoric acid are obtained.

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3.21 In the button cells widely used in watches and other devices the following reaction takes place: Zn(s) + Ag2O(s) + H2O(l) → Zn2+(aq) + 2Ag(s) + 2OH– (aq) Determine ?r G ? and E ? for the reaction.

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