Questions 15 through 17 pertain to the situation described below: An air tank of volume 2.70 × 10-2 m³ has air pressure 7.30 x 106 Pa and temperature 30.0°C inside and is left at a lake bottom at 15.0°C. If there is a leak on the tank and the pressure and temperature inside have dropped to 2.70 × 106 Pa and 11.0°C over a period of time. (15) How many moles of air are in the tank initially? (A) 70.2 mol; (B) 72.2 mol; (C) 74.2 mol; (D) 76.2 mol; (E) 78.2 mol. (16) How many moles of air have leaked out of the tank? (A) 39.3 mol; (B) 41.3 mol; (C) 43.3 mol; (D) 45.3mol; (E) 47.3 mol. (17) What is the work done by the air leaked into the water? (A) 143 kJ; (B) 133 kJ; (C) 123 kJ; (D) 113 kJ; (E) 103 kJ.

One type of gas mixture used in anesthesiologyis a 50%/50% mixture (by volume) of nitrous oxide (N2O) and oxygen(O2), which can be premixed and kept in a cylinder for later use.Because these two gases don’t react chemically at or below 2000 psi, attypical room temperatures they form a homogeneous single gas phase,which can be considered an ideal gas. If the temperature drops below-6C, however, N2O may begin to condense out of the gas phase. Thenany gas removed from the cylinder will initially be nearly pure O2; asthe cylinder empties, the proportion of O2 will decrease until the gascoming from the cylinder is nearly pure N2O. In another test, the valve of a 500 L cylinder full of the gas mixture at 2000 psi (gauge pressure) is opened wide so that the gas rushes out of the cylinder very rapidly. Why might some N2O condense during this process? (a) This is an isochoric process in which the pressure decreases, so the temperature also decreases. (b) Because of the rapid expansion, heat is…

A 0.210 g sample of a metal, M, reacts completely with sulfuric acid according to the reaction   M(s)+H2SO4(aq)⟶MSO4(aq)+H2(g) A volume of 219 mL of hydrogen gas is collected over water; the water level in the collecting vessel is the same as the outside level. Atmospheric pressure is 1.0079 bar and the temperature is 25 °C. The vapor pressure of water at 25 °C is 0.03167 bar. Calculate the molar mass of the metal.

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