What is the mole fraction of $\mathrm{C}_3 \mathrm{H}_8$ (g) in the flask before reaction?

A gas mixture at room temperature contains 10.0 mo! CO and 12.5 mol O2. (a) Compute the mole fraction of CO in the mixture. (b) The mixture is then hea ted, and the CO starts to react with the O2 to give CO2:

$$CO(g)+½O2(g)→CO2(g)$$

At a certain point in the heating, 3.0 mo! CO2 is present. Determin e the mole fraction of CO in the new mixture.

A sample of 3.00 g of

$$SO_2(g)$$

or iginally in a 5.00-L vessel at

$$21 ^ { \circ } \mathrm { C }$$

is transferred to a 10.0-L vessel at

$$26 ^ { \circ } \mathrm { C }$$

A sample of 2.35 g of

$$N_2(g)$$

originally in a 2.50-L vessel at

$$20 ^ { \circ } \mathrm { C }$$

is tran sferred to this same 10.0-L vessel. What is the partial pressure of

$$N_2(g)$$

in this vessel?

A sample of 3.00 g of

$$SO_2(g)$$

or iginally in a 5.00-L vessel at

$$21 ^ { \circ } \mathrm { C }$$

is transferred to a 10.0-L vessel at

$$26 ^ { \circ } \mathrm { C }$$

A sample of 2.35 g of

$$N_2(g)$$

originally in a 2.50-L vessel at

$$20 ^ { \circ } \mathrm { C }$$

is tran sferred to th is same 10.0-L vessel. What is the total pressure in the vessel?

A mixture consisting of 7.0 g of CO and 10.0 g of SO2, two atmospheric pollutants, has a pressure of 0.33 atm when placed in a sealed container. What is the partial pressure of CO?

Assume that a single cylinder of an automobile engine has a volume of

$$524 cm^3.$$

How many grams of

$$C_8H_{18}$$

could be combusted by this quantity of

$$O_2,$$

assuming complete combustion with formation of

$$CO_2$$

and

$$H_2O?$$

Assume that a single cylinder of an automobile engine has a volume of

$$524 cm^3.$$

If the cylinder is full of air at

$$74 ^ { \circ } \mathrm { C }$$

and 0.980 atm, how many moles of

$$O_2$$

are present? (The mole fraction of

$$O_2$$

in dry air is 0.2095.)

An equimolar mixture of Ne and Xe is accidentally placed in a container that has a tiny leak. After a short while, a very small proportion of the mixture has escaped. What is the mole fraction of Ne in the effusing gas?

A glass vessel fitted with a stopcock va lve has a mass of 337.428 g when evacuated. When filled with Ar, it has a mass of 339.854 g. When evacuated and refilled with a mixture of Ne and Ar, under the same conditions of temperature and pressure, it has a mass of 339.076 g. What is the mole percent of Ne in the gas mixture?

Rank the following gases from least dense to most den se at 1.00 atm and 298 K: $SO_2, HBr, CO_2.$

Which of the following statements best explains why nitrogen gas at STP is less dense than Xe gas at STP? (a) Because Xe is a noble gas, there is less tendency for the Xe atoms to repel one another, so they pack more densely in the gaseous state. (b) Xe atoms have a higher mass than

$$N_2$$

molecules. Because both gases at STP have the same number of molecules per unit volume, the Xe gas must be denser. (c) The Xe atoms are larger than

$$N_2$$

molecules and thus take up a larger fra ction of the space occupied by the gas. (d) Because the Xe atoms are much more mass ive than the

$$N_2$$

molecul es, they move more slowly and thus exert less upward force on the gas container and make the gas appear denser.

Which of the following statements best explains why alpha emission is relatively common, but proton emission is extremely rare? Alpha particles are the nuclei of an inert gas.

Calculate the molar mass of a vapor that has a density of 7.135 g/L at

$$12 ^ { \circ } \mathrm { C }$$

and 743 torr.

In the Dumas-bulb technique for determining the molar mass of an unknown liquid, you vaporize the sample of a liquid th at boils below

$$100 ^ { \circ } \mathrm { C }$$

in a boiling-water bath and determine the mass of vapor required to fill the bulb. From the following data, calculate the molar mass of the unknown liquid: mass of unknown vapor, 1.012 g; volume of bulb,

$$354 cm^3$$

pressure, 742 torr; temperature,

$$99 ^ { \circ } \mathrm { C }$$