Then we can use the ideal gas law, with the given temperature and pressure, to determine the volume of gas produced. Here we have a stoichiometry problem where we need to find the number of moles of H 2 produced. What volume of H 2 is produced at 299 K and 1.07 atm when 55.8 g of Zn metal react with excess HCl? Zn(s) + 2HCl(aq) → ZnCl 2(aq) + H 2(g) The ideal gas law can also be used in stoichiometry problems. Isolating T all by itself on one side, we get T = (0. The mmHg, L, and mol units cancel, leaving the K unit, the unit of temperature. We can either convert this to atmospheres or use the value of the ideal gas constant that includes the mmHg unit. Pressure is given in units of millimeters of mercury. We can use the molar mass of Hg to convert to the number of moles. We are not given the number of moles of Hg directly, but we are given a mass. Table 6.1 "Values of the Ideal Gas Law Constant " lists the numerical values of R.Īt a given temperature, 0.00332 g of Hg in the gas phase has a pressure of 0.00120 mmHg and a volume of 435 L. Its value depends on the units used to express pressure and volume. The constant R is called the ideal gas law constant. It relates the four independent properties of a gas at any time. This equation is called the ideal gas law A gas law that relates all four independent physical properties of a gas under any conditions. We define this constant with the symbol R, so the previous equation is written as P V n T = R So P V n T = constantīecause pressure, volume, temperature, and amount are the only four independent physical properties of a gas, the constant in the above equation is truly a constant indeed, because we do not need to specify the identity of a gas to apply the gas laws, this constant is the same for all gases. By analogy to Avogadro’s law, n is positioned in the denominator of the fraction, opposite the volume. Are there any gas laws that relate the physical properties of a gas at any given time?Ĭonsider a further extension of the combined gas law to include n. So far, the gas laws we have considered have all required that the gas change its conditions then we predict a resulting change in one of its properties. Apply the ideal gas law to molar volumes, density, and stoichiometry problems.Apply the ideal gas law to any set of conditions of a gas.
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