SOLVED

21) What is the difference between “normal boiling point” and “boiling point” of a liquid? A) “Normal boiling point” is a boiling point of a liquid at normal (standard) pressure and temperature, while “boiling point” is measured at any other conditions of pressure and temperature. B) “Normal boiling point” is a boiling point of 1 mol of a liquid with a surface of 1 m2, while “boiling point” is boiling temperature for any other amount of a substance. C) “Normal boiling point” is a boiling point a liquid has at 1 atm of pressure; “boiling point” is a boiling temperature of a liquid at any other pressure. D) “Normal boiling point” and “boiling point” are synonyms. E) “Normal boiling point” refers to 1 g of substance; “boiling point” refers to any other amount of substance. 22) Which of the following describe the critical point of a liquid? I)the temperature and pressure at which a liquid’s meniscus disappears II)the point where the vapor pressure curve intersects the fusion temperature curve III)the highest temperature and pressure at which a liquid can exist IV)the highest temperature at which it is possible to obtain a liquid from its vapor by increasing pressure A) I), II), III) B) I), III), IV) C) II), III) D) II), III), IV) E) I), IV) 23) A liquid is in equilibrium with its vapor. If some of the vapor is allowed to escape, what is the immediate result? A) The condensation rate decreases. B) The vaporization rate increases. C) The condensation rate increases. D) The vaporization rate decreases. E) The rates of condensation and vaporization are not effected. 24) When a liquid is in dynamic equilibrium with its vapor at a given temperature, the following conditions could exist: I) There is no transfer of molecules between liquid and vapor. II) The vapor pressure has a unique value. III) The opposing processes, (liquid to vapor) and (vapor to liquid), proceed at equal rates. IV) The concentration of vapor is dependent on time. Which of the above choices are applicable? A) I B) II and III C) I, II, and III D) II and IV E) II, III and IV 25) When a liquid is in equilibrium with its vapor in a closed container: A) the rate at which molecules from the liquid phase enter the gas phase exactly equals the rate at which molecules from the gas phase pass into the liquid phase B) a change in temperature will not change the pressure in the container C) the amount of gas in the container must exactly equal the amount of liquid D) molecules cannot go from the liquid phase to the gas phase because the amount of liquid in the container is constant E) the vapor will gradually change back to the liquid state, that is, no vapor will be left 26) Under which of the following conditions will vaporization best occur? A) high mass, large surface area, high kinetic energy B) weak forces between molecules, high kinetic energy, large surface area C) high molecular energy, small surface area D) low kinetic energy, strong molecular forces, large surface area E) small surface area, low kinetic energy, low molecular mass 27) Which of the following keeps the rate of vaporization unchanged? A) closing container lid B) increasing forces between molecules C) increasing mass of molecule D) decreasing temperature E) decreasing surface area 28) A liquid has a normal boiling point of 78°C and its vapor pressure is 400 mmHg at 50°C. To compute the molar heat of vaporization, one needs: A) the mole weight B) all information has been provided C) the vapor pressure at another temperature D) the specific heat E) molarity 29) The phenomenon in which a steel needle can, with proper care, be made to float on the surface of some water illustrates a property of liquids known as: A) compressibility B) polarizability C) surface tension D) triple point E) viscosity 30) Which of the following statements about viscosity are true: I)Viscosity is liquid’s resistance to flow. II)Viscosity decreases with a decrease in temperature. III)Viscosity is not related to the forces between molecules in a liquid. IV)Viscous liquids have low rate flows. A) I) and IV) B) I) and III) C) I) and II) D) II) and IV) E) III and IV)