Volume at Standard Temperature and Pressure

In Example 11.6 (in the Check step), we saw that the volume occupied by 1 mol of gas at 0 °C (273.15 K) and 1 atm is 22.4 L. These conditions are called standard temperature and pressure (STP), and the volume occupied by 1 mol of gas imder these conditions is called the molar volume of an ideal gas at STP. Using the ideal gas law, we can confirm that the molar volume at STP is 22.4 L. 

Under standard conditions, therefore, we can use this ratio as a conversion factor. 

For example, suppose we wanted to calculate tite number of liters of CO2 gas that forms at STP when 0.879 moles of CaCO undergoes this reaction  

We strategize by drawing a solution map that shows how to convert from mol CaC03 to mol CO2 to L CO2 using the molar volume at STP. 

1 mol CaCOa 1 mol CO2 (from balanced equation given in problem) 

The volume occupied by one mole of a substance is its molar volume. For gases, we often specify the molar volume under conditions known as standard temperature (T = 0 °C or 273 K) and pressure (P = 1.00 atm), abbreviated as STP. Using the ideal gas law, we can determine that the molar volume of an ideal gas at STP is  

The molar volume of an ideal gas at STP is useful because—as we saw in the Check steps of Examples 5.5 and 5.6—it gives us a way to approximate the volume of an ideal gas under conditions that are close to STP. 

Assuming ideal behavior, which of these gas samples will have the greatest volume at STP  

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AH gas volumes at standard temperature and pressure. To convert to cal, divide by 4.184. 

A ratio of the net output (in moles or volume at standard temperature and pressure per unit time) of CO2 divided by the net uptake (in identical units) of O2 at a given site. 

This means that if it is desired to calculate the effective work potential of an explosive, it is necessary to calculate.or assume the water-gas reaction constant of the detonation products behind the reaction zone, calculate the heat liberated by the decomposition reaction at this equilibrium (Qc) and calculate.the pressure developed on the basis of the gaseous products. A simple approximation of this value can be arrived at by multiplying the heat value Qc by the volume of gas formed at the maximum temperature but expressed as volume at standard temperature and pressure (Vc)... 

Practice Problem 12.9 Calculate the volume at standard temperature and pressure of a sample of gas that has a volume of 49.7 mL at 52°C and 811 torr. I... 

The flow rate F (based on volume at standard temperature and pressure) can be easily determined by the measurement of d(pV)ldt. In a vacuum system, which has a constant volume, measuring V(dpldl) is the easiest and perhaps the most accurate way to determine the flow rate. This can be done by the following procedure. 

Skill 2.1a-Calculate molar mass, mass, number of particles, and volume, at standard temperature and pressure (STP) for elements and compounds... 

Helium isotope measurements in ocean ridge and island basalts provide some of the most basic geochemical information on mantle source reservoirs. More helium isotope analyses have been performed for oceanic volcanic rocks than for other noble gas species, and helium isotopes have played a leading role in the study of mantle heterogeneity. Helium isotope analyses are readily performed by modern mass spectrometers because there is a general absence of atmospheric contamination in samples due to the low concentration of helium in air (5.24 parts per million by volume at standard temperature and pressure). There are 2 naturally occurring isotopes of helium. He is much less abundant than " He for example, the atmospheric He/" He ratio (Ra) is 1.39x10 (Mamyrin et al. 1970 Clarke et al. 1976). Nearly all of the terrestrial " He has been produced as a-particles from the radioactive decay of U, U and Th over... 

It is further assumed in the BET theory that adbi (= c) is constant for a given temperature. The sum l (/0i) from / = 1 to i = n is the fractional extent of adsorption (because d, is the fraction of occupied sites corresponding to the (th layer which have i molecules stacked one upon the other). The actual number of molecules adsorbed is thus z fiOi). Now the ratio zhm is equivalent to the ratio qlqm of the quantity of adsorbate adsorbed (expressed as either mass or volume at standard temperature and pressure) to the total capaeity of the adsorbent. Because the adsorbate vapour totally condenses when the saturated vapour pressure ps is reached, then 01 = 02 when p = Ps and so... 

The study of these systems is carried out by determining the so-called adsorption isotherm. An adsorption isotherm consists in the evaluation of the amount of adsorbed gas as a funetion of the equilibrium pressure at a constant temperature. The physical adsorption is the predominant process for inert gases at temperatures below their critical point. Normally, in the adsorption isotherm, pressure is expressed as the relative pressure plpQ (t q saturation pressure at a given temperature) and the amount absorbed expressed as a mass of gas or its volume at standard temperature and pressure. 

The unit barrer is a non-SI unit in the cgs system for the gas permeability P of thin materials in honor of the New Zealand chemist Richard M. Barrer (1910 1996), who was a leader in research on the diffusion of gases. The permeability P of 1 barrer corresponds to the flow rate of 10 cubic centimeters per second (volume at standard temperature and pressure, 0 °C and 1 atm), times 1 cm of membrane thickness, per square centimeter of membrane area, and centimeter of mercury difference in pressure between both sides of the membrane. That is, a permeability of 1 barrer = 10 cm s cmHg" (Equation 2), or. 

For both P and Q, the quantity of permeant can be expressed by mass, moles, or gaseous volume at standard temperature and pressure. These can readily be converted from one unit into another. 

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