The lowest pressure achieved in the laboratory is about 1.0 x 10 ^-15 torr. how many molecules of gas are present in a 1.0 L container at this pressure?

A mixture contained zinc sulfide, ZnS, and lead sulfide, PbS. A sample of the mixture weighing 6.12 g was reacted with an excess of hydrochloric acid. The reactions are ZnS(s)+2HCL(aq)ZnCl2(aq)+H2S(g)PbS(s)+2HCL(aq)PbCl2(aq)+H2S(g) If the sample reacted completely and produced 1.049 L of hydrogen sulfide, H2S, at 23C and 762 mmHg, what were the percentages of ZnS and PbS in the mixture?

Given that a sample of air is made up of nitrogen, oxygen, and argon in the mole fractions 0.78 N2, 0.21 O2, and 0.010 Ar, what is the density of air at standard temperature and pressure?

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.

If equal masses of O2 and N2 are placed in separate containers of equal volume at the same temperature, which of the following statements is true? If false, explain why it is false. (a) The pressure in the flask containing N2 is greater than that in the flask containing O2. (b) There are more molecules in the flask containing O2 than in the flask containing N2.

47 HCl(g) reacts with ammonia gas, NH3(g), to form solid ammonium chloride. If a sample of ammonia occupying 250 mL at 21 C and a pressure of 140 torr is allowed to react with excess HCl, what mass of NH4Cl will form?

Ammonia gas is synthesized by combining hydrogen and nitrogen: 3 H2(g) + N2(g) 2 NH3(g) (a) If you want to produce 562 g of NH3, what volume of H2 gas, at 56 C and 745 mm Hg, is required? (b) Nitrogen for this reaction will be obtained from air. What volume of air, measured at 29 C and 745 mm Hg pressure, will be required to provide the nitrogen needed to produce 562 g of NH3? Assume the sample of air contains 78.1 mole % N2.

Given that a sample of air is made up of nitrogen, oxygen, and argon in the mole fractions 0.78 N2, 0.21 O2, and 0.010 Ar, what is the density of air at standard temperature and pressure?

A chemist weighed out 5.14 g of a mixture containing unknown amounts of BaO(s) and CaO(s) and placed the sample in a 1.50-L flask containing CO2(g) at 30.0C and 750. torr. After the reaction to form BaCO3(s) and CaCO3(s) was completed, the pressure of CO2(g) remaining was 230. torr. Calculate the mass percentages of CaO(s) and BaO(s) in the mixture.

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.