魅影直播

Question: (II)If the pressure in a gas is tripled while its volume is held constant, by what factor does\({v_{{\rm{rms}}}}\)change?

Question: In the relation \(\Delta l = \alpha {l_{\rm{o}}}\Delta T\), should \({l_{\rm{o}}}\) be the initial length, the final length, or does it matter?

Question: (II)Show that the rms speed of molecules in a gas is given by\({{\bf{v}}_{{\bf{rms}}}}{\bf{ = }}\sqrt {{\bf{3P/\rho }}} \)where P is the pressure in the gas and\({\bf{\rho }}\)is the gas density.

Question: (II)Show that for a mixture of two gases at the same temperature, the ratio of their rms speeds is equal to the inverse ratio of the square roots of their molecular masses,\(\frac{{{{\bf{v}}_{\bf{1}}}}}{{{{\bf{v}}_{\bf{2}}}}}{\bf{ = }}\sqrt {\frac{{{{\bf{M}}_{\bf{2}}}}}{{{{\bf{M}}_{\bf{1}}}}}} \).

Question: (II)What is the rms speed of nitrogen molecules contained in an\({\bf{8}}{\bf{.5}}\;{{\bf{m}}^{\bf{3}}}\)volume at 2.9 atm if the total amount of nitrogen is 2100 mol?

Question: (II)Two isotopes of uranium,\({}^{{\bf{235}}}{\bf{U}}\)and\({}^{{\bf{238}}}{\bf{U}}\)(the superscripts refer to their atomic masses), can be separated by a gas diffusion process by combining them with fluorine to make the gaseous compound\({\bf{U}}{{\bf{F}}_{\bf{6}}}\). Calculate the ratio of the rms speeds of these molecules for the two isotopes, at constant T. Use Appendix B for masses.

Question: (I)\({\rm{C}}{{\rm{O}}_{\rm{2}}}\)exists in what phase when the pressure is 35 atm and the temperature is 35掳C (Fig. 13鈥�23)?

Question: A flat bimetallic strip consists of a strip of aluminum riveted to a strip of iron. When heated, the strip will bend. Which metal will be on the outside of the curve? Why? (Hint: See Table 13鈥�1.)

(III) Air that is at its dew point of 5掳C is drawn into a building where it is heated to 22掳C. What will be the relative humidity at this temperature? Assume constant pressure of 1.0 atm. Take into account the expansion of the air.

(II) Estimate the time needed for a glycine molecule (see Table 13鈥�4) to diffuse a distance of \(25\;\mu {\rm{m}}\) in water at 20掳C if its concentration varies over that distance from \(1.00\;{\rm{mol/}}{{\rm{m}}^{\rm{3}}}\) to \(0.50\;{\rm{mol/}}{{\rm{m}}^{\rm{3}}}\)? Compare this 鈥渟peed鈥� to its rms (thermal) speed. The molecular mass of glycine is about 75 u.