A laboratory vacuum pump can reduce the pressure in a chamber to 1.0 × 10-7 Pa. If the volume of the chamber is 0.500 m3 and the temperature is 27°C, how many molecules are left inside the chamber? (NA = 6.022 × 1023 molecules/mol, R = 8.31 J/mol • K)
1.2 × 1013
1.2 × 1014
2.4 × 1013
2.4 × 1012
1.2 × 1012
A laboratory vacuum pump can reduce the pressure in a chamber to 1.0 × 10-7 Pa.?
2016-06-20 8:08 pm
回答 (1)
2016-06-20 8:17 pm
Let N be the number of molecules inside the chamber.
Pressure, P = 1.0 × 10⁻⁷ Pa
Volume, V = 0.500 m³
No. of moles, n = N/(6.022 × 10²³) mol
Gas constant, R = 8.314 J / (mol K)
Absolute temperature, T = (273 + 27) K = 300 K
PV = nRT
n = PV/(RT)
N/(6.022 × 10²³) = (1.0 × 10⁻⁷) × 0.500 / (8.314 × 300)
N = (1.0 × 10⁻⁷) × 0.500 × (6.022 × 10²³) / (8.314 × 300)
Number of molecules inside the chamber, N = 1.2 × 10¹³
...... The answer is : 1.2 × 10¹³
Pressure, P = 1.0 × 10⁻⁷ Pa
Volume, V = 0.500 m³
No. of moles, n = N/(6.022 × 10²³) mol
Gas constant, R = 8.314 J / (mol K)
Absolute temperature, T = (273 + 27) K = 300 K
PV = nRT
n = PV/(RT)
N/(6.022 × 10²³) = (1.0 × 10⁻⁷) × 0.500 / (8.314 × 300)
N = (1.0 × 10⁻⁷) × 0.500 × (6.022 × 10²³) / (8.314 × 300)
Number of molecules inside the chamber, N = 1.2 × 10¹³
...... The answer is : 1.2 × 10¹³
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