A sample of He gas has a volume of 565 mL, has a pressure of 984 mm Hg, and is at a temperature of 8.70 °C. Calculate the amount (in moles) of He in the gas sample. mol

A sample of a compound of xenon and fluorine was confined in a bulb with a pressure of 18 tor. Hydrogen was added to the bulb until the pressure was 72 torr. Passage of an electric spark through the mixture produced Xe and HF. After the HF was removed by reaction with solid KOH, the final pressure of xenon and unreacted hydrogen in the bulb was 36 torr. What is the empirical formula of the xenon fluoride in the original sample? (Note: Xenon fluorides contain only one xenon atom per molecule.)

57 What volume of hydrogen gas, in liters, is produced by the reaction of 3.43 g of iron metal with 40.0 mL of 2.43 M HCl? The gas is collected at 2.25 atm of pressure and 23 C. The other product is FeCl2?

Consider the following sketch. Each square in bulb A represents a mole of atoms X. Each circle in bulb B represents a mole of atoms Y. The bulbs have the same volume, and the temperature is kept constant. When the valve is opened, atoms of X react with atoms of Y according to the following equation: 2X(g)+Y(g)X2Y(g)The gaseous product is represented as and each represents one mole of product. (a) IfP A=2.0 atm, what is P8 before the valve is opened and the reaction is allowed to occur? What is P A+P B? (b) Redraw the sketch to represent what happens after the valve is opened. (c) What is PA? What is PB? What is P A+P B? Compare your answer with the answer in part (a).

You have a gas, one of the three known phosphorus-fluorine compounds (PF3, PF3, and P2F4). To find out which, you have decided to measure its molar mass. (a) First, yon determine that the density of the gas is 5.60 g/L at a pressure of 0.971 atm and a temperature of 18.2 C. Calculate the molar mass and identify the compound. (b) To check the results from part (a), you decide to measure the molar mass based on the relative rales of effusion of the unknown gas and CO2. You find that CO2 effuses at a rate of 0.050 mol/min, whereas the unknown phosphorus fluoride effuses at a rate of 0.028 mol/min. Calculate the molar mass of the unknown gas based on these results.

Many nitrate salts can be decomposed by heating. For example, blue, anhydrous copper(II) nitrate produces the gases nitrogen dioxide and oxygen when heated. In the laboratory, you find that a sample of this salt produced a 0.195-g mixture of gaseous NO2 and O2 with a total pressure of 725 mm Hg at 35 C in a 125-mL flask (and black, solid CuO was left as a residue). What is the average molar mass of the gas mixture? What are the mole fractions of NO2 and O2 in the mixture? What amount of each gas b in the mixture? Do these amounts reflect the relative amounts of NO2 and O2 expected based on the balanced equation? Is it possible that the fact that some NO2 molecules combine to give N2O4 plays a role? Heating copper(II) nitrate produces nitrogen dioxide and oxygen gas and leaves a residue of copper(ll) oxide.

Which of the following statements is(are) true? a. If the number of moles of a gas is doubled, the volume will double, assuming the pressure and temperature of the gas remain constant. b. If the temperature of a gas increases from 25C to 50C, the volume of the gas would double, assuming that the pressure and the number of moles of gas remain constant. c. The device that measures atmospheric pressure is called a barometer. d. If the volume of a gas decreases by one half, then the pressure would double, assuming that the number of moles and the temperature of the gas remain constant.

Plot the data given in Table 5.3 for oxygen at 0C to obtain an accurate molar mass for O2. To do this, calculate a value of the molar mass at each of the given pressures from the ideal gas law (we will call this the apparent molar mass at this pressure). On a graph show the apparent molar mass versus the pressure and extrapolate to find the molar mass at zero pressure. Because the ideal gas law is most accurate at low pressures, this extrapolation will give an accurate value for the molar mass. What is the accurate molar mass?