--%>
Assignment Help - homework help

What are isotonic and hypotonic solutions?

The two solutions which are having equivalent osmotic pressure are called isotonic solutions. The isotonic solutions at the same temperature also have same molar concentration. If we have solutions having different osmotic pressures then the solution having different osmotic pressures is said to be hypertonic solution and the solution having lower osmotic pressure is called hypotonic solution.

0.9% (mass/volume) aqueous solution of sodium chloride is called normal saline solution and is isotonic with the fluid inside the human red blood cells (RBC). Therefore, during intravenous injections, the medicines are mixed with saline water before the injection. This avoids the blood cells from shrinking or bursting. However, solutions having concentration grater or less than 0.9% (mass/volume) are not safe. For example, if the NaCl solution is less concentrated i.e. hypotonic w.r.t. human blood, its osmotic pressure will be low and finally burst. On the other hand, if the NaCl solution is more concentrated, i.e. hypertonic, its osmotic pressure is high and the water will move out of the cell causing the cell to shrink due to plasmolysis.

Some common phenomena and osmosis

Osmosis provides logical explanation to some common processes that we come across.

(i) Shrieving of raw mangoes to pickle.

Raw mangoes when place in concentrated solution of common salt lose water through osmosis and ultimately shrivel into pickle.

(ii) Revival of wilted flowers and limped carrots: flowers revive and regain their freshness when place in fresh water because of osmosis. Carrots get limed due to loss of water to atmosphere. However, when limped carrots are placed in water, they become firm due to inflow of water because of osmosis.

(iii) Swelling of tissues in people consuming more salt: people consuming more salt and excessively salty food suffer from edema which is swelling and puffiness produced because of retention of water in the tissue cells and intercellular space.

(iv) Preservation of meat: the preservation of meat against bacterial action is done by salting it. Similarly, fruits are preserved against bacteria by adding sugar. The bacteria on salted meat or on candid fruits loses water through osmosis shrivels and ultimately dies.

(v) Absorption of water by plants: plants absorb water from the soil through their roots due to osmosis because the cell sap in the root hair cells has higher osmotic pressure than that of soil water.

Osmotic pressure is a colligative property. For a given solvent the osmotic pressure relies only upon the molar concentration of solute but does not depend on its nature. Osmotic pressure is linked with the number of moles of the solute by the subsequent relation:

πV = nRT

Or, π = n/V (RT)

π = CRT

C = conc. In mol L-1

R = gas constant (bar LK-1 mol-1)

T = temperature (K); n = mol of solute

V = volume of soln. (L);

   Related Questions in Chemistry

  • Q : What is laser and explain its working?

    Laser action relies on a non-Boltzmann population inversion formed by the absorption of radiation and vibrational deactivation that forms a long lived excited electronic state. An excited state molecule can move to a lower energy state or return to the

    		•
  • Q : Hybridization Atomic orbitals can be

    Atomic orbitals can be combined, in a process called hybridization, to describe the bonding in polyatomic molecules. Descriptions of the bonding in CH4 can be used to illustrate the valence bond procedure. We must arrive a

    		•
  • Q : Meaning of molality of a solution The

    The molality of a solution will be: (i) Number of moles of solute per 1000 ml of solvent (ii) Number of moles of solute per 1000 gm of solvent (iii) Number of moles of solute per 1000 ml of solution (iv) Number of gram equivalents of solute per 1000 m

    		•
  • Q : Reactivity of allyl and benzyl halides

    why allyl halide and haloarenes are more reactive than alkyl halide towards nucleophilic substitution

    		•
  • Q : Finding strength of HCL solution Can

    Can someone please help me in getting through this problem. 1.0 gm of pure calcium carbonate was found to require 50 ml of dilute  HCL for complete reaction. The strength of the HCL  solution is given by: (a) 4 N  (b) 2 N  (c) 0.4 N  (d) 0.2 N

    		•
  • Q : Film Mass Transport Sulfur trioxide

    Sulfur trioxide (SO3) is manufactured by the gas-phase oxidation of SO2 over a platinum catalyst: SO2 + ½ O2 à SO3 The catalyst is a non-porous ext

    		•
  • Q : Problem on physical and thermodynamic

    The shells of marine organisms contain calcium carbonate CaCO3, largely in a crystalline form known as calcite. There is a second crystalline form of calcium carbonate known as aragonite. Physical and thermodynamic properties of calcite and aragonite at 298

    		•
  • Q : Neutralization of sodium hydroxide How

    How much of NaOH is needed to neutralise 1500 cm3 of 0.1N HCl (given = At. wt. of Na =23): (i) 4 g  (ii) 6 g (iii) 40 g  (iv) 60 g

    		•
  • Q : Describe Thermodynamics Properties The

    The free energy property leads to convenient expressions for the volume and pressure dependence of internal energy, enthalpy and the heat capacities.All the properties of a chemical system, a sample of a substance, or a mixture of substances have some fixe

    		•
  • Q : Avogadro's hypothesis Law Principle

    Avogadro's hypothesis Law Principle- Berzelius, a chemist tried

    		•