Universal Gas Constant
Universal Gas Constant - Related Videos
10:23
Ideal Gas Law
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2023
Source: Laboratory of Dr. Andreas Züttel - Swiss Federal Laboratories for Materials Science and Technology The ideal gas law describes the behavior of most common gases at near-ambient conditions and the tendency of all chemical matter in the dilute limit. It is a fundamental relationship between three measurable macroscopic system variables (pressure, temperature, and volume) and the number of molecules of gas in the system, and is therefore an essential link between the microscopic and the...
04:06
Ideal Gas Law - Concepts
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2020
Derivation of the Ideal Gas Law Gases are a fundamental state of matter. A gas is a collection of molecules that have a significant distance between their molecules. Due to this distance, colorless gases are invisible to the human eye and are studied using four measurable parameters: pressure (P), volume (V), number of moles (n), and temperature (T). The ideal gas law is a mathematical equation that relates all of these parameters. It is a combination of several different laws that describe the...
02:46
Calculating the Equilibrium Constant
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2020
The equilibrium constant for a reaction is calculated from the equilibrium concentrations (or pressures) of its reactants and products. If these concentrations are known, the calculation simply involves their substitution into the Kc expression. For example, gaseous nitrogen dioxide forms dinitrogen tetroxide according to this equation: When 0.10 mol NO2 is added to a 1.0-L flask at 25 °C, the concentration changes so that at equilibrium, [NO2] = 0.016 M and [N2O4] = 0.042 M. The value of the...
07:51
Gas Absorber
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2023
Source: Michael G. Benton and Kerry M. Dooley, Department of Chemical Engineering, Louisiana State University, Baton Rouge, LA Gas absorbers are used to remove contaminants from gas streams. Multiple designs are used to accomplish this objective1. A packed bed column uses gas and liquid streams running counter to each other in a column packed with loose packing materials, such as ceramics, metals, and plastics, or structured packing1. The packed bed uses surface area created by the packing to...
07:32
Newton's Law of Universal Gravitation
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2023
Source: Ketron Mitchell-Wynne, PhD, Asantha Cooray, PhD, Department of Physics & Astronomy, School of Physical Sciences, University of California, Irvine, CA Legend states that Isaac Newton saw an apple fall from a tree. He noticed the acceleration of the apple and deduced that there must have been a force acting upon the apple. He then surmised that if gravity can act at the top of the tree, it can also act at even larger distances. He observed the motion of the moon and the orbits of the...
FAQs
The value 8.314 J mol^-1 K^-1 is consistent with energy expressed in joules, amount in moles, and temperature in kelvin. Pressure and volume must therefore be represented in a way that matches the energy unit used in the calculation. Checking units before substitution prevents dimensional inconsistencies and helps identify errors in calculated gas quantities.
Kelvin is the temperature scale specified for the given value of R, so temperatures must be converted to kelvin before applying the ideal gas law. This requirement affects every calculation involving temperature, whether the unknown is pressure, volume, or amount. Using another temperature scale without appropriate conversion produces an incompatible numerical result.
In PV = nRT, R supplies the proportional relationship between the measurable variables pressure, volume, and temperature and the chemical amount n. This lets a set of bulk gas measurements be translated into moles, or lets a known amount predict a macroscopic state variable. The relationship is specifically framed by the ideal-gas model.
Rearranging PV = nRT does not remove the need for dimensional consistency. The pressure-volume term must correspond to the energy units represented by R, while n and T must match moles and kelvin. Comparing units on both sides provides a practical check before interpreting the calculated pressure, volume, temperature, or amount.
First identify the known values among pressure, volume, amount, and temperature, then rearrange PV = nRT so the desired variable is isolated. Insert values only after confirming compatible units, including kelvin for temperature and the units associated with the selected form of R. The resulting calculation can predict or quantify a gas-state variable.
Gas measurements can be converted into an amount of substance by applying the ideal gas relationship, allowing gas volume or pressure data to enter quantitative chemical calculations. Once the amount is determined, it can be related to stoichiometric quantities in the reaction under study. This makes R useful when experiments report macroscopic gas behavior but chemistry requires moles.
The same constant also connects ideal-gas calculations with thermodynamic relationships involving enthalpy and entropy. Consequently, R is not limited to predicting pressure, volume, temperature, or amount; it helps place gas behavior within broader energy and disorder relationships. Its use links quantitative gas chemistry with thermodynamic analysis.