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Which is the larger species in each pair? 

a. Li o r Li+

b. Cs1- o r Cs

c. Cr1-  or Cr3+

d. O or O2-

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A quantity of CO gas occupies a volume of 0.48 L at 1.0 atm and 275 K. The pressure of the gas is lowered and its temperature is raised until its volume is 1.3 L. Find the density of the CO under the new conditions. 

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A 10-liter container is filled with 0.10 mol of H2(g) and heated to 3000 K causing some of the H2(g) to decompose into H(g). The pressure is found to be 3.0 atm. Find the partial pressure of the H(g) that foms from H2 at this temperature. (Assume two significant figures for the temperature.) 

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A gas mixture composed of helium and argon has a density of 0.670 g/L at a 755 Hg and 298 K. What is the composition of the mixture by volume? 

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A sample of N2O3(g) has a pressure of 0.017 atm. The temperature (in K) is then doubled and the N2O3 undergoes complete decomposition to NO2(g) and NO(g). Find the total pressure of the mixture of gases assuming constant volume and no additional temperature change. 

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The radius of a xenon atom is 1.3 X 10 –8 cm. A 100-mL flask is filled with Xe at a pressure of 1.0 atm and a temperature of 273 K. Calculate the fraction of the volume that is occupied by Xe atoms. (Hint: The atoms are spheres.) 

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A particular balloon can be stretched to a maximum surface area of 1257 cm 2. The balloon is filled with 3.0 L of helium gas at a pressure of 755 torr and a temperature of 298 K. The balloon is then allowed to rise in the atmosphere. If the atmospheric temperature is 273 K, at what pressure will the balloon burst? (Assume the balloon to be in the shape of a sphere.) 

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An 11.5-mL sample of liquid butane (density = 0.573 g/ mL) is evaporated in an otherwise empty container at a temperature of 28.5 °C. The pressure in the container following evaporation is 892 torr. What is the volume of the container? 

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Twenty-five milliliters of liquid nitrogen (density = 0.807 g/mL) is poured into a cylindrical container with a radius of 10.0 cm and a length of 20.0 cm. The container initially contains only air at a pressure of 760.0 mmHg (atmospheric pressure) and a temperature of 298 K. If the liquid nitrogen completely vaporizes, what is the total force (in Ib) on the interior of the container at 298 K? 

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The emission of NO2 by fossiI fuel combustion can be prevented by injecting gaseous urea into the combustion mixture. The urea reduces NO (which oxidizes in air to form NO2) according to the reaction: 

2 CO(NH2)2(g) + 4 NO(g) + O2(g) → 4 N2(g) + 2 CO2(g) + 4 H2O(g) 

Suppose that the exhaust stream of an automobile has a flow rate of 2.55 L/s at 655 K and contains a partial pressure of NO of 12.4 torr. What total mass of urea is necessary to react completely with the NO formed during 8.0 hours of driving? 

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In a common classroom demonstration, a balloon is filled with air and submerged in liquid nitrogen. The balloon contracts as the gases within the balloon cool. Suppose the balloon initially contains 2.95 L of air at a temperature of 25.0 °C and a pressure of 0.998 atm. Calculate the expected volume of the balloon upon cooling to -196 °C (the boiling point of liquid nitrogen). When the demonstration is carried out, the actual volume of the balloon decreases to 0.61 L. How does the observed volume of the balloon compare to your calculated value? Can you explain the difference? 

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Ammonium nitrate decomposes explosively upon heating according to the balanced equation: 

2 NH4NO3(s) → 2 N2(g) + O2(g) + 4 H2O(g)

Calculate the total volume of gas (at 125 °C and 748 mmHg) produced by the complete decomposition of 1.55 kg of ammonium nitrate. 

 

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Consider the reaction:

2 SO2(g) + O2(g) → 2 SO3(g)

b. If 187.2 mL of SO3 is collected (measured at 315 K and 50.0 mmHg), what is the percent yield for the reaction? 

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When hydrochloric acid is poured over potassium sulfide, 42.9 mL of hydrogen sulfide gas is produced at a pressure of 752 torr and 25.8 °C. Write an equation for the gas-evolution reaction and determine how much potassium sulfide (in grams) reacted. 

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Consider the reaction:

2 Ag2O(s) → 4 Ag(s) + O2(g)

If this reaction produces 15.8 g of Ag(s), what total volume of gas can be collected over water at a temperature of 25 °C and a total pressure of 752 mmHg? 

 

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A gaseous hydrogen and carbon containing compound is decomposed and found to contain 85.63% C and 14.37% H by mass. The mass of 258 mL of the gas, measured at STP, was 0.646 g. What is the molecular formula of the compound? 

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A 118-mL flask is evacuated and found to have a mass of 97.129 g. When the flask is filled with 768 torr of helium gas at 35 °C, it has a mass of 97.171 g. Was the helium gas pure?

 

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The mass of an evacuated 255-mL flask is 143.187 g. The mass of the flask filled with 267 torr of an unknown gas at 25 °C is 143.289 g. Calculate the molar mass of the unknown gas.

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A 2.85-g sample of an unknown chlorofluorocarbon decomposes and produces 564mL of chlorine gas at a pressure of 752mmHg and a temperature of 298 K. What is the percent chlorine (by mass) in the unknown chlorofluorocarbon? 

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Modern pennies are composed of zinc coated with copper. A student determines the mass of a penny to be 2.482 g and then makes several scratches in the copper coaling (to expose the underlying zinc). The student puts the scratched penny in hydrochloric acid, where the following reaction occurs between the zinc and the HCl (the copper remains undissolved): 

Zn(s) + 2 HCl(aq) → H2(g) + ZnCl(aq)

The student collects the hydrogen produced over water at 25 °C. The collected gas occupies a volume of 0.899 L at a total pressure of 79 J mmHg. Calculate the percent zinc (by mass) in the penny. (Assume that all the Zn in the penny dissolves.) 

 

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Use the van der Waals equation and the ideal gas equation to calculate the pressure exerted by 1.000 mol of Cl2 in a volume of 5.000 L. at a temperature of 273.0 K. Explain why the two values are different. 

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Which postulate of the kinetic molecular theory breaks down under conditions of low temperature? Explain. 

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Which postulate of the kinetic molecular theory breaks down under conditions of high pressure? Explain. 

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The graph shows the distribution of molecular velocities for the same molecule at two different temperatures (T1 and T2). Which temperature is greater? Explain. 

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The graph shows the distribution of molecular velocities for two different molecules (A and B) at the same temperature. Which molecule has the higher molar mass? Which molecule would have the higher rate of effusion? 

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