1st year Chemistry Chapter 2 Experimental Techniques in Chemistry Question an Answers
Short and Simple Question an Answer
Q.1: Greater the temperature of the gas closer the straight line of p verses 1/V to the pressure axis. Justify? co
Ans: When the temperature of same gas increased for the number of moles, then the volume increase at the same pressure. The inverse of volumes decrease at the same pressure. So the points for the graph is above the temperature graph.
Q.2: Hydrogen gas diffuses faster than CO2?
Ans: As the molecular weight of H₂ is lighter than CO₂ and according to the Grahams law the rate of diffusion of gases is inversely proportional to the square root of their molecular weights. So hydrogen gas diffuses faster than CO₂. bingspun
Q.3: Why is the Boyle’s law applicable only to the ideal gas?
Ans: Boyle’s law is applicable to those gases which have no forces of attractions among the molecules. Such gases are ideal so Boyle’s law of applicable to only ideal gases. Kiritalianja
Q.4: Charles’s law is not obeyed when the temperature is measured an Celsius Scale? Justify it?
Ans: The foundation stone of Charles’s law is the absolute scale of temperature which starts
Q.5: Dalton’s law of partial pressure is only applicable to those mixtures of gases which are ideal, and they do not react with each other under the green condition? Why?
Ans: Dalton’s law is applicable to the mixtures of gases. All the gases in the mixture should have no forces of attraction or repulsions so that they may be able to axert their own pressures independently. This is only possible when the gases are non-polar.
Q.6: How the value of the general gas constant “R” can be derived with the help of Avogadro’s law?
Ans: According to Avogadro’s law, the volume of one of all the ideal gases at S. T. P are 22.4 dm³.
Q.7: Calculate the S.I unit of R?
Ans: According to Avogadro’s law we put the values of P. V. T and n the value of R.
Q.8: The pressure cooker helps in cooking the meat and vegetables quickly even at high altitude?
Ans: In pressure cooker vapors are not allowed to escape, they therefore develop more vapour pressure in the cooker and boiling point of water increases. Thus vegetables and meat is cooked quickly in the cooker even at high altitude.
Q.9: HF is the weaker acids in halogen acid explain?
Ans: In halogen acids HF is the weaker acid because in HF hydrogen bonding is present due to which HF does not loose H* easily as compared to other acids.
Q.10: Boiling point of water is higher than that of HF?
Ans: Boiling point of H2O is greater than that of HF because F atom form one H bond and per molecule while H₂O form two H bonds or molecule.
Q.11: When water freezes ix occupies in ore space and its density decreases. Explain?
Ans: When water freezes its molecules are arranged regularly and empty spaces are produced due to which percentage of volume is increased, hence density decreases.
Q.12: Vapour Pressure, Boiling point increases with increase in external pressure?
Ans: V.p and b.p increases with the increase in external liquid becomes equal to external pressure. Thus by increasing external pressure V.P and b.p also increase.
Q.13: Explain why metallic crystals are good conductor of electricity, hut ionic crystal are not?
Ans: In metallic crystals valence electrons are loosely held and move freely throughout the crystal. Therefore they are good conductors of electricity. In ionic crystals ions are present which are not able to move in an electric field due to strong inter ionic attraction. Hence ionic crystals do not conduct electricity.
Q.14: Explain why density of a liquid decreases with increase in temperature?
Ans: When a liquid is heated the average K.E. of the molecules increases and intermolecular force of attraction decreases. Consequently, the intermolecular distance increases, this results in expansion of liquid and density is lowered.
Q.15: Density of H₂O is maximum at 40 C? Explain?
Ans: The density of water is maximum at 40C because the molecules form big clusters at this temperature due to extensive hydrogen bonding.
Q.16: Liquid are miscible while solids are not?
Ans: Solid cannot mix-up ordinarily to form homogeneous mixture like liquids and gases because the solid particles possess only vibration motion and no transitional motion as in liquid.
Q.17: Rate of diffusion in liquids in slow as compared to gases?
Ans: Diffusion occurs due to transnational motion of the matter particles from one place to another. In gases particles possess greater intermolecular space where liquids have little intermolecular spaces therefore in case gases molecules are easily pass through the intermolecular spaces of other liquid for mixing up.
Q.18: The effect of pressure on the volume of liquid is negligible?
Ans: The molecules of a liquid are so close that their intermolecular distance can not be decreased appreciably by applying pressure. That is why the effect of pressure on the volume of liquid is negligible.
Q.19: When a gas obeys the Boyle’s the isothermal for the gas can be plotted? Justify?
Ans: Isotherms are the graphs between pressure and volume at constant temperature and number of moles. This condition is fulfilled by Boyle’s law. The word isotherms means “same temperature”.