Avogadro s law

In process engineering, moles are used extensively in performing (lie calculations. A mole is defined as that mass of a substance that is numen cally equal to its molecular weight. Avogadro s Law states that identical volumes of gas at the same temperature and pressure contain equal numbers of molecules for each gas. It can be reasoned that these identical volumes will have a weight proportional to the molecular weight of the gas. If the mass is expressed as... 

Avogadro s Law, 16 Axial compressor, 13, 14 application range, 14, 226 balance piston, 252... 

According to Avogadro s law, equal volumes of all gases under similar conditions contain the same number of molecules. Consequently the weights of equal volumes or the densities of gases will represent the ratio of their molecular weights. If the densities are compared with hydrogen as the unit, the ratio... 

We can evaluate the constant (kik2k3) in this equation by taking advantage of Avogadro s law, which states that equal volumes of all gases at the same temperature and pressure contain the same number of moles. For this law to hold, the constant must be the same for all gases. Ordinarily it is represented by the symbol R. Both sides of the equation are multiplied by P to give the ideal gas law... 

Avogadro s law, referred to on page 107, was proposed in 1811 by an Italian physicist at the University of Turin with the improbable name of Lorenzo Romano Amadeo Carlo Avogadro di Quarequa e di Cerreto (1776-1856). 

Stanislao Cannizzaro, professor of chemistry at f the University of Genoa. At a conference held in I Karlsruhe in 1860, he persuaded the chemistry community of the validity of Avogadro s law and showed how it could be used to determine molar and atomic masses, i The quantity now called "Avogadro s number (6.02 x 10 /mol) was first estimated in = 1865, nine years after Avogadro died. Not until... 

Kinetic theory A theory of matter based on the mathematical description of the relationship between pressures, volumes, and temperatures of gases (PVT phenomena). This relationship is summarized in the laws of Boyle s law, Charle s law, and Avogadro s law. 

Background Avogadro s law (Vin2 = V2ni), where moles, n = mw (grams/mole) exPresses the relationship between molar mass, the actual mass and the number of moles of a gas. The molar volume of a gas at STP, VSTP is equal to the volume of the gas measured at STP divided by the number of moles VSTp = pp. Dalton s Law of Partial Pressure (Ptotai = Pi + P2 + P3 +. ..) and the derivation, Pi = pp Ptotai will also be used in this experiment to predict the volume occupied by one mole of hydrogen gas at STP. 

For gases and vapors, exposure concentrations are traditionally expressed in parts per million (ppm). The calculation for the ppm of a gas or vapor in an air sample is based on Avogadro s Law, which states that Equal volumes contain equal numbers of molecules under the same temperature and pressure. In other words, under standard temperature and pressure (STP), one gram-molecular weight (mole) of any gas under a pressure of one atmosphere (equivalent to the height of 760 mm mercury) and a temperature of 273 K has the same number of molecules and occupies the same volume of 22.4 liters. However, under ambient conditions, the volume of 22.4 liters has to be corrected to a larger volume based on Charles Law, which states that at constant pressure the volume of gas varies directly with the absolute temperature. Thus, at a room temperature of 25° C, one mole of a gas occupies a volume of 24.5 liters. 

It is possible to combine Avogadro s law and the combined gas law to produce the ideal gas equation, which incorporates the pressure, volume, temperature, and amount relationships of a gas. The ideal gas equation has the form of... 

Another useful relationship is one derived from Avogadro s law 1 mol of any gas occupies 22.4 L at STP (standard temperature and pressure of 0°C (273 K) and 1 atm). If you can find the volume at STP, you can then convert it to moles using this relationship and then to grams, if needed. 

In all the gas law problems so far, the amount of gas has been constant. But what if the amount changes That is where Avogadro s law comes into play. 

If a container is kept at constant pressure and temperature, and you increase the number of gas particles in that container, the volume will have to increase in order to keep the pressure constant. This means that there is a direct relationship between the volume and the number of moles of gas (n). This is Avogadro s law and mathematically it looks like this ... 

The values of P, T, and n may be used to determine the volume of a gas. If this volume is to be used with Avogadro s law of 22.4 L/mol, the combined gas law must be employed to adjust the volume to STE This equation will use the measured values for P and Talong with the calculated value of V. These values are combined with STE conditions (0°C (273.15 K) and 1.00 atm) to determine the molar volume of a gas. 

Avogadro s law Avogadro s law states that there is a direct relationship between the volume and the number of moles of gas. 

You should recall from the review of the mole unit that the reaction coefficients (2, 1, and 2 in the preceding example) can be interpreted as molecules, or as moles, or as volumes. This is because Avogadro s law holds for all gases. The number of molecules in 1 mole of a gas is known to be... 

The relations known as Boyle s law, Charles law, and Avogadro s law can be combined into an exceedingly useful formula called the Ideal Gas Equation,... 

Avogadro s law equal volumes of gases at the same temperature and pressure that contain the same number of molecules. 

Of course, the real universe can fight back by changing another variable. In the real universe, for example, tires spring leaks. In such a situation, gas particles escape the confines of the tire. This escape decreases the number of particles, n, within the tire. Cranky, tire-iron wielding motorists on the side of the road will attest that decreasing n decreases volume. This relationship is sometimes expressed as Avogadro s law ... 

Avogadro s Law states that equal volumes of all gases under the conditions of STP contain the same number of molecules. It implies that the molar volume of one gas is equal to the molar volume of any other gas, that is, the molar volume of any gas at 0°C and 1 atm pressure is very close to 22.4 liters. This may be illustrated by the decomposition of NG. 

As discussed in Chapter 3, the 19th-century Italian scientist Amedeo Avogadro hypothesized that the volume of a gas is a function of the number of gas particles it contains. In other words, as the number of gas particles increases, so does the volume, assuming a constant pressure and temperature. This relationship is known as Avogadro s Law. An easy way to demonstrate this law is to blow into an empty plastic bag. The more air molecules you blow into the bag, the bigger its volume. Mathematically, we can depict Avogadro s Law by the following equation ... 

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