Questions
Question 1
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Find the volume of \(1.20\,\mathrm{mol}\) of ideal gas at \(300\,\mathrm{K}\) and \(1.00\times10^5\,\mathrm{Pa}\).
Question 2
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A gas sample has \(p=2.0\times10^5\,\mathrm{Pa}\), \(V=3.0\times10^{-3}\,\mathrm{m^3}\), and \(T=290\,\mathrm{K}\). Find \(n\).
Question 3
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For a fixed amount of ideal gas at constant temperature, the volume is halved. What happens to the absolute pressure?
Question 4
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A fixed amount of ideal gas changes from \(p_1=100\,\mathrm{kPa}\), \(V_1=4.0\,\mathrm{L}\), \(T_1=300\,\mathrm{K}\) to \(V_2=2.5\,\mathrm{L}\), \(T_2=360\,\mathrm{K}\). Find \(p_2\).
Question 5
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Use \(pV=Nk_BT\) to find the number of molecules in a \(2.0\times10^{-3}\,\mathrm{m^3}\) gas sample at \(p=1.5\times10^5\,\mathrm{Pa}\) and \(T=300\,\mathrm{K}\).
Question 6
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An ideal gas has density \(\rho\), molar mass \(M\), pressure \(p\), and temperature \(T\). Derive \(\rho=pM/(RT)\).
Question 7
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A gas cylinder of volume \(0.080\,\mathrm{m^3}\) contains oxygen with molar mass \(3.2\times10^{-2}\,\mathrm{kg\,mol^{-1}}\) at \(280\,\mathrm{K}\) and \(5.0\times10^5\,\mathrm{Pa}\). Find the gas mass.
Question 8
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A fixed amount of ideal gas satisfies \(pV/T=\mathrm{constant}\). It is compressed to one third of its original volume while its Kelvin temperature doubles. Find \(p_2/p_1\).
Question 9
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A real gas is modeled by \(\left(p+a n^2/V^2\right)(V-nb)=nRT\). Explain what physical effects the \(a\) and \(b\) corrections represent, and state a condition under which the model reduces to \(pV=nRT\).
Question 10
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A fixed amount of ideal gas changes between two equilibrium states. Derive an expression for \(T_2\) in terms of \(p_1,V_1,T_1,p_2,V_2\), and state why gauge pressure cannot be used in this expression.
Question 11
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A sealed rigid tank contains ideal gas at \(p_1=2.4\times10^5\,\mathrm{Pa}\) and \(T_1=300\,\mathrm{K}\). The gas is heated to \(T_2=450\,\mathrm{K}\). Find the final absolute pressure.
Question 12
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For one mole of a van der Waals gas, \(\left(p+a/V_m^2\right)(V_m-b)=RT\). In the dilute limit \(V_m\gg b\), derive the first-order approximation \(p\approx RT/V_m+(RTb-a)/V_m^2\).
Question 13
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A gas has \(p=1.20\times10^5\,\mathrm{Pa}\), \(T=300\,\mathrm{K}\), and molar mass \(2.8\times10^{-2}\,\mathrm{kg\,mol^{-1}}\). Find its density using the ideal-gas model.
Question 14
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A gas obeys \(pV=nRT\). At fixed \(n\), pressure is increased by a factor of \(3\) while volume is reduced by a factor of \(2\). Find \(T_2/T_1\).
Question 15
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For one mole of a van der Waals gas, explain why the term \(V_m-b\) makes the pressure larger than the ideal-gas value at the same \(T\) and measured \(V_m\), if attractions are ignored.
Question 16
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Derive the ideal-gas density relation \(p=\rho RT/M\) and state the assumptions behind it.
Question 17
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A gas is described by \(pV=nRT\). Explain why the equation relates equilibrium states rather than every instant during a rapid compression.
Question 18
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Using \(pV=Nk_BT\), show that doubling molecule number at fixed \(V\) and \(T\) doubles pressure, and interpret microscopically.
Question 19
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In the van der Waals equation, explain why attractions reduce the measured wall pressure even though the correction is written as \(p+a n^2/V^2\).
Question 20
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A gas model gives \(pV/T\) constant for fixed amount. Explain two ways experimental data can reveal departure from ideal-gas behavior.