Gases density/molar mass

The ideal gas law can be recast in additional ways to determine other properties of gases. In this section, we use it to find gas density, molar mass, and the partial pressure of each gas in a mixture. 

Determine the number of free electrons in gold, assuming that each atom contributes one electron to the electron gas . The molar mass of gold is 0.19697 kg moP, and the density is 19281 kgm . ... 

Gas Formula Molar mass/g moF Density/gdm Molar gas volume/dm moM... 

Use the ideal gas law equation to solve for P, V, T, or n of a gas when given three of the four values in the Ideal gas law equation. Calculate density, molar mass, or volume of a gas in a chemical reaction. 

At 25°C and 380 mm Hg, the density of sulfur dioxide is 1.31 g/L. The rate of effusion of sulfur dioxide through an orifice is 4.48 mL/s. What is the density of a sample of gas that effuses through an identical orifice at the rate of 6.78 mL/s under the same conditions What is the molar mass of the gas ... 

The density, d, of a gas, like that of any substance, is the mass of the sample divided by its volume, d = tn/V. Because the densities of gases are so low, they are usually expressed in grams per liter (g-L ). The density of air, for instance, is about 1.6 g-L-1 at SATP. Because the mass of the sample is equal to the amount in moles times the molar mass, m = nM, and n = PV/RT, it follows that... 

We see that, for a given pressure and temperature, the greater the molar mass of the gas, the greater its density. Equation 10 also shows that, at constant temperature, the density of a gas increases with pressure. When a gas is compressed, its density increases because the same number of molecules are confined in a smaller volume. Similarly, heating a gas that is free to expand at constant pressure increases the volume occupied by the gas and therefore reduces its density. The effect of temperature on density is the principle behind hot-air balloons the hot air inside the envelope of the balloon has a lower density than that of the surrounding cool air. Equation 10 is also the basis for using density measurements to determine the molar mass of a gas or vapor. 

EXAMPLE 4.6 Sample exercise Calculating the molar mass of a gas from its density... 

The molar concentrations and densities of gases increase as they are compressed but decrease as they are heated. The density of a gas depends on its molar mass. 

I 4 Determine molar mass from gas density and vice versa (Example 4.6). 

The ideal gas equation and the molecular view of gases lead to several useful applications. We have already described how to cany out calculations involving P-V-n-T relationships. In this section, we examine the use of the gas equation to determine molar masses, gas density, and rates of gas movement. 

Specific heat Molar flow of inert air Equilibrium constant Overall mass transfer capacity coefficient base on the gas phase Molar flow of solute-free water Pressure Density... 

Carbon dioxide gas (C02) has a molar mass of 44 g/mol. The two major components of air, which are oxygen and nitrogen, have molar masses of 32 g/mol and 28 g/mol, respectively. Calculate the room-temperature densities in g/L of nitrogen (N2), oxygen (02), and carbon dioxide (C02) gases. 

Instruments with indirect pressure measurement. In this case, the pressure is determined as a function of a pressure-dependent (or more accurately, density-dependent) property (thermal conductivity, ionization probability, electrical conductivity) of the gas. These properties are dependent on the molar mass as well as on the pressure. The pressure reading of the measuring instrument depends on the type of gas. 

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