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A solution of glucose (molar mass = 180 g mol–1) in water is labelled as 10% (by mass). What would be the molality and molarity of the solution ? (Density of solution = 1.2 g mL–1)
Concept: Colligative Properties and Determination of Molar Mass - Introduction
Write any two differences between amorphous solids and crystalline solids
Concept: Amorphous and Crystalline Solids
Give reasons : In stoichiometric defects, NaCl exhibits Schottky defect and not Frenkel defect.
Concept: Imperfections in Solids >> Types of Point Defects - Stoichiometric Defects
Give reasons : Silicon on doping with Phosphorous forms n-type semiconductor.
Concept: Properties of Solids: Electrical Properties >> Applications of n-type and p-type Semiconductors
An element with density 11.2 g cm–3 forms a f.c.c. lattice with edge length of 4 × 10–8 cm.
Calculate the atomic mass of the element.
(Given : NA = 6.022 × 1023 mol–1)
Concept: Calculations Involving Unit Cell Dimensions
Examine the given defective crystal:
Answer the following questions :
(i) What type of stoichiometric defect is shown by the crystal?
(ii) How is the density of the crystal affected by this defect?
(iii) What type of ionic substances show such defect?
Concept: Imperfections in Solids >> Types of Point Defects - Stoichiometric Defects
Calculate the mass of a compound (molar mass = 256 g mol−1) to be dissolved in 75 g of benzene to lower its freezing point by 0.48 K (Kf = 5.12 K kg mol−1).
Concept: Colligative Properties and Determination of Molar Mass >> Osmosis and Osmotic Pressure
An unripe mango placed in a concentrated salt solution to prepare pickle, shrivels because ______.
Concept: Colligative Properties and Determination of Molar Mass >> Reverse Osmosis and Water Purification
Why are aquatic species more comfortable in cold water in comparison to warm water?
Concept: Colligative Properties and Determination of Molar Mass >> Reverse Osmosis and Water Purification
When 19.5 g of F – CH2 – COOH (Molar mass = 78 g mol−1), is dissolved in 500 g of water, the depression in freezing point is observed to be 1°C. Calculate the degree of dissociation of F – CH2 – COOH.
[Given: Kf for water = 1.86 K kg mol−1]
Concept: Abnormal Molar Masses
Why is the value of van't Hoff factor for ethanoic acid in benzene close to 0.5?
Concept: Abnormal Molar Masses
Why is boiling point of 1 M NaCl solution more than that of 1 M glucose solution?
Concept: Abnormal Molar Masses
A non-volatile solute 'X' (molar mass = 50 g mol−1), when dissolved in 78 g of benzene, reduced its vapour pressure to 90%. Calculate the Mass of X dissolved in the solution.
Concept: Colligative Properties and Determination of Molar Mass >> Relative Lowering of Vapour Pressure
Calculate the boiling point elevation for a solution prepared by adding 10 g of MgCl2 to 200 g of water, assuming MgCl2 is completely dissociated.
(Kb for Water = 0.512 K kg mol−1, Molar mass MgCl2 = 95 g mol−1)
Concept: Colligative Properties and Determination of Molar Mass >> Elevation of Boiling Point
Determine the osmotic pressure of a solution prepared by dissolving 2.32 × 10−2 g of K2SO4 in 2L of solution at 25°C assuming that K2SO4 is completely dissociated.
(R = 0.082 L atm K−1 mol, Molar mass K2SO4 = 174 g mol−1)
Concept: Colligative Properties and Determination of Molar Mass >> Osmosis and Osmotic Pressure
When 25.6 g of sulphur was dissolved in 1000 g of benzene, the freezing point lowered by 0.512 K. Calculate the formula of sulphur (Sr).
(Kf for benzene = 5.12 K kg mol−1, Atomic mass of sulphur = 32 g mol−1)
Concept: Colligative Properties and Determination of Molar Mass >> Depression of Freezing Point
From the given cells:
Lead storage cell, Mercury cell, Fuel cell and Dry cell
Answer the following:
(i) Which cell is used in hearing aids?
(ii) Which cell was used in Apollo Space Programme?
(iii) Which cell is used in automobiles and inverters?
(iv) Which cell does not have long life?
Concept: Batteries >> Primary Batteries
Calculate e.m.f of the following cell at 298 K:
2Cr(s) + 3Fe2+ (0.1M) → 2Cr3+ (0.01M) + 3 Fe(s)
Given: E°(Cr3+ | Cr) = – 0.74 VE° (Fe2+ | Fe) = – 0.44 V
Concept: Galvanic or Voltaic Cells - Introduction
Following reactions occur at cathode during the electrolysis of aqueous silver chloride solution :
`Ag^+(aq)+e^(-)rarrAg(s)" "" "" "E^@=+0.80V`
`H^+(aq)+e^(-)rarr1/2H_2(g)" "" "" " E^@=0.00V`
On the basis of their standard reduction electrode potential (E°) values, which reaction is feasible at the cathode and why ?
Concept: Relation Between Gibbs Energy Change and Emf of a Cell
