Question :
41) How much heat energy needed to convert 10.0 g : 1282407
41) How much heat energy is needed to convert 10.0 g of ice at −10 °C to liquid water at 10 °C?
Specific heat of ice = 2.09 J/(g °C)Heat of fusion of ice = 334 J/gSpecific heat of water = 4.18 J/g °C
A) 5270 J
B) 1,070 J
C) 6,210 J
D) 3970 J
42) The calculation set-up below is used to determine how much heat is needed to convert 50 g of ice at −20 °C to steam at 300 °C. Which constant does C represent?
(A)(50 g)(20 °C) + (heat of fusion)(50 g) + (B)(50 g)(100 °C) + (heat of vap.)(50 g) + (C)(50 g)(200 °C) = total heat
A) specific heat of ice
B) specific heat of water
C) specific heat of steam
D) heat capacity of water
43) The calculation set-up below is used to determine how much heat is needed to convert 50 g of ice at −20 °C to steam at 300 °C. Which constant does A represent?
(A)(50 g)(20 °C) + (heat of fusion)(50 g) + (4.18 J/g °C)(50 g)(100 °C) + (B)(50 g) + (C)(50 g )(200 °C) = total heat
A) heat of condensation
B) specific heat of ice
C) specific heat of water
D) heat of vaporization of water
44) Which of the following statements concerning evaporation is correct?
A) Molecules with energies considerably above average escape from the liquid.
B) Decreasing the surface area of the liquid increases the rate of evaporation.
C) During evaporation, the temperature of the liquid changes.
D) Increasing the surface area of the liquid decreases the rate of evaporation.
45) A nonvolatile liquid would ________.
A) have weak attractive forces between molecules
B) have a high vapor pressure at room temperature
C) be a very “explosive” substance
D) have strong attractive forces between molecules
46) The vapor pressure of SnCl4 reaches 400 mm Hg at 92 °C, the vapor pressure of SnI4 reaches 400 mm Hg at 315 °C, the vapor pressure of PBr3 reaches 400 mm Hg at 150 °C, and the vapor pressure of PCl3 reaches 400 mm Hg at 57 °C. At 175 °C, which substance would have the lowest vapor pressure?
A) PBr3
B) SnI4
C) SnCl4
D) PCl3
47) What effect will decreasing the temperature of a liquid by 15 °C at constant pressure have on the magnitude of its vapor pressure?
A) increase
B) decrease
C) no change
D) insufficient information given
48) The boiling point of a liquid is ________.
A) the temperature at which the rate of sublimation and evaporation are equal
B) always 100 °C or greater
C) the temperature at which the vapor pressure of the liquid equals the pressure over the liquid
D) the temperature at which sublimation occurs
49) Which statement about the boiling point of water is incorrect?
A) The boiling point is greater than 100 °C in a pressure cooker.
B) The boiling point is less than 100 °C for locations at low elevations.
C) At sea level and at a pressure of 760 mm Hg, the boiling point is 100 °C.
D) In a pressure cooker, shorter cooking times are required due to the change in boiling point.
50) The normal boiling point of a substance is determined by its molecular mass and its intermolecular forces. Considering these two factors, predict the order of increasing boiling points for the following substances: CH4, CS2, KBr, NH3.
A) CS2 < CH4 < KBr < NH3
B) CH4 < CS2 < NH3 < KBr
C) NH3 < KBr < CS2 < CH4
D) CH4 < KBr < NH3 < CS2
