課程名稱︰普通化學甲
課程教師︰蘇志明
開課學院：理學院
開課系所︰化學系
考試時間︰10/8 10:20~~12.10
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試題 :
1.Consider the following unbalanced reaction:
P4(s) + F2(g) --> PF3(g)
How many grams of F2 are needed to produced 100g of PF3 if the reaction
has a 75% yield?
2.A sample of a mixture containing only sodium chloride and potassium chloride
has a mass of 3.00g.When this sample is dissolved in water and excess silver
nitrate is added,a white precipitate(silver chloride)forms.After filtration
and drying,this precipitate has the mass 6.00g.calculate the mass percent of
each component in the mixture.
3.Citric aacid,which can be obtained from lemon juice,has the molecular
formula C6H8O7.A 0.250g sample of citric acid dissolved in 25.0 ml of water
requires 37.2 ml of 0.105M NaOH for complete neutralization.How many acidic
hydrogens per molecule does citric acid have?
4.A solution of permanganate is standarized by nitration with oxalic acid
(H2C2O4).It required 25.00 ml of the permanganate solution to react
completely with 0.100g of oxalic acid.The unbalanced equation for the
reaction is
- 2+
MnO4 (aq) + H2C2O4(aq) ----> Mn (aq) + CO2(g)
(a)What is the molarity of the permanganate solution?
(b)What mass of CO2 is produced from the reaction?
5.
(a)Starting from the Maxwell-Boltzmann speed distribution
m
f(u)=4π(————————)^(3/2)*u^2*e(-mu^2/2KB*T)
2πKBT
derive the equation for the most probable speed Ump
(b)What is the root mean square of a gas with a molecular weight of M at
temperature T.In the textbook,we obtained the expression for Urms from the
kinetic molecular theory.One also could derive Urms from the speed
distribution shown in (a).How do you do this?Just outlining your calculation
procedure is good enough.
o
6.A 100L flask contains a mixture of methane aand argon at 25 C.The mass of
argon present is 200g and the mole fraction of methane in the mixture is 0.60.
Calculate the total Kinetic energy of the gaseous mixture.
7.The nitrogen content of organic compounds can be determined by Dumas method.
The compound is first reacted by passage over hot CuO(s):
hot
Compound ------>N2(g) + CO2(g)+ H2O(g)
The gaseous products are then passed through a concentrated solution
of KOH to remove the CO2.The gas is then contains N2 and meanwhile is
saturated with water capor.In a given experiment a 0.253g of a compound
o
produced 31.8 ml of N2 saturated with water vapor at 25 C and pressure
726torr.What is the mass percent of nitrogen in the compound?
(The vapor pressure of water at 25 degree C is 23.8 torr.)
Some constants:
R=1.987cal/mol-deg=8.314J/mol-deg
KB=1.381*10^(-23) J/K
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