What do you mean by elevation in boiling point? Explain with the help of a graph.

The boiling point of the solvent is elevated by the addition of non-volatile solute to it. This is known as elevation of boiling point. If we plot graphs between the different values of temperature and the vapour pressure for the pure solvent as well as for its solution, the two curves that are formed may be given as follows. Let P be the atmospheric pressure, then the boiling point temperature of the pure solvent is T 1 and that of the solution is T 2 . The elevation in boiling point, ∆ T b is given as, ∆ T b = T 2 - T 1

Calculate the mole fraction of ethylene glycol C 2 H 6 O 2 if 20% by mass of C 2 H 6 O 2 is present in that solution.

Given that 20% of ethylene glycol by mass is present. It means that solution has 20g of ethylene glycol and 80g of water. Now, Molar mass of C 2 H 6 O 2 = 62 g mol - 1 Number of moles of C 2 H 6 O 2 = 20 62 = 0 . 322 Number of moles of water is 80 18 = 4 . 44 Mole fraction of ethylene glycol is calculated by using the formula, Mole fraction of ethyl glycol = number of moles of solute number of moles of solute and solvent Mole fraction of ethyl glycol = 0 . 322 0 . 322 + 4 . 444 = 0 . 068 Mole fraction of water = 1 - 0 . 068 = 0 . 932

Define molality. Write its formula also.

Molality is one of the ways of expressing concentration of solutions. It is defined as the number of moles of solute dissolved in 1 Kg of solvent. It is a temperature independent quantity. Molality (m) = number of moles of the solute mass of solvent in kg

2 . 82 gm of glucose (Molecular mass= 180) is dissolved in 30 gm of water. Calculate molality of the solution.

Given, Mass of solute = 2 . 82 gm Mass of solvent = 30 gm Number of moles of glucose = n 1 = 2 . 82 180 = 0 . 01567 Number of moles of water = n 2 = 30 18 = 1 . 667 Therefore, molality of the solution = n 1 n 2 × 1000 M . wt of solvent = 0 . 01567 1 . 667 × 1000 18 = = 0 . 522 molal .

3 . 65 gm HCl is dissolved in 500 gram water. Determine the molality of the solution.

Given data, Mass of solute = w B = 3 . 65 g , Mass of solvent = = w A = 500 g = 0 . 5 kg Molar mass of solute M b = ( HCl ) = 36 . 5 g mol - 1 Molality of the solution = w B M B × w A = 3 . 65 36 . 5 × 0 . 5 = 0 . 2 mol kg - 1 Therefore, molality of the given solution is = 0 . 2 mol kg - 1 .

Calculate molality of 1 M concentrated solution of NaNO 3 if density of solution is 1 . 25 g cm - 3

We know that molar mass of solute is 85 gm Volume of solution is 1000 ml . Given that density of solution is 1 . 25 g cm - 3 Mass = 1 . 25 × 1000 = 125 gm m = density × volume Mass of solvent = mass of solution - mass of solute = 1250 - 85 = 1165 gm Molality can be calculated by the formula; m = no . of mole of solute one kg of solvent = 1 1165 × 1000 = 0 . 85 m

What is free energy? Derive Gibbs-Helmholtz equation

Free energy is defined as a quantity that is used determine the maximum amount of work done in a thermodynamic system when the temperature and pressure are kept constant. Free energy is an extensive property, and it depends on the initial and final states of the system. Gibbs free energy is an extensive property and a state function. The change in gibbs energy is given as ∆ G sys = ∆ H sys - T ∆ S sys - S ∆ T sys At constant temperature ∆ T = 0 Hence, gibbs free energy is ∆ G = ∆ H - T ∆ S , where ∆ H is change in enthalpy, ∆ S is change in entropy of the system.

Calculate normality of solution, containing 4 gm NaOH in 250 ml aqueous solution.

Normality is defined as the number of gram or mole equivalents of solute present in one litre of a solution. We know that molar mass of NaOH is 40 . Gram equivalent of NaOH = 4 40 = 1 10 Normality can be calculated by using the formula; N = Gram equivalent volume of the solution N = 1 10 250 1000 = 1 10 × 1000 250 = 0 . 4 N

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Write any two differences between non-ideal solutions with positive and negative deviation.

Chapter-Wise 3D Chemistry Videos from Embibe Experts EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR CHEMISTRY

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Elevation in Boiling Point

The boiling point of a liquid is the temperature at which its vapour pressure becomes equal to atmospheric pressure. Let’s learn about the elevation in boili...

08 min 43 sec

Non-ideal Solutions

We know that an ideal solution is a theoretical concept. So, what are non-ideal solutions? Why do they show a deviation from Raoult's law? Let's explore!

08 min 23 sec

Azeotropic Mixtures

Certain liquid mixtures have a definite composition and boil at a constant temperature. They are called azeotropes. Let’s explore the cause of their behaviour!

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