شرح للكيمياء و أسئلة مراجعة

[سحر البيان]

28. Write the ideal gas equation. Give the units for each term in the equation.
A) PV = nRT; P in torr, V in L, n in mol, R in Latm/Kmol, T in C.
B) PV = nRT; P in torr, V in L, n in mol, R in Latm/Kmol, T in K.
C) PV = nRT; P in atm, V in L, n in mol, R in Latm/Kmol, T in K.
D) PV = nRT; P in atm, V in L, n in mol, R in Latm/Kmol, T in C .

31. Why is the density of a gas much lower than that of a liquid or solid under atmospheric conditions?
A) There are much weaker intermolecular forces between gas molecules.
B) Gas molecules are separated by distances that are large compared to their size.
C) Gas molecules are not very compressible.
D) Both a and b.

لأن الروابط بين الغازات متباعده مما يجعلها تشغل حجم كبير بالتالي كثافتها أقل

32. What units are normally used to express the density of gases?
A) g/mL
B) kg/L
C) mg/L
D) g/L

68. Refer to Dalton's law of partial pressures and explain what mole fraction is.
A) The number of moles of one component.
B) The ratio of the number of moles of one component to the number of moles of all components present.
C) The number of moles of one component divided by 100.
D) The ratio of the number of moles of all components present to the number of moles of one component.

69. Does mole fraction have units?
A) yes, mol
B) yes, mol-1
C) no

الكسر المولي ليس له وحدات لأن البسط و المقام بالمولات تحذف مع بعض ...

29. What are standard temperature and pressure (STP)?
A) 0 C, 1 torr
B) 25 C, 1 torr
C) 0 C, 1 atm
D) 25 C, 1 atm

30. What is the volume of one mole of an ideal gas at STP?
A) 24.5 L
B) 22.4 L
C) 1.0 L
D) 10.0 L