2007 MC Q40
1) When 10g of PURE calcium carbonate(molar mass=100.1g) react with excess HCl, 2.4 dm of carbon dioxide was obtained at room temp and pressure. However, in a similar experiment using 10g of IMPURE calcium carbonate, 2.5dm^3 of carbon dioxide was obtained. What would the impurity be?
(molar mass: MgCO3=84.3g, ZnCO3=125.4g, FeCO3=115.8g, CuCO3=123.5g)
A.MgCO3
B.ZnCO3
C.FeCO3
D.CuCO3
Ans is A
2)A gas X is bubbled into a solution of Y as shown in the above diagram.
In which of the following combinations would X react with Y ?
X Y
A.Ammonia Potassium nitrate
B.Chlorine Potassium nitrate
C.Carbon dioxide Sodium hydroxide
D.Sulpur dioxide Iron (II) sulphate
Ans is C,why?
3) NaCl+ chlorine water--> what's the observation??
chem ce
2008-04-28 10:54 pm
回答 (1)
2008-04-28 11:06 pm
✔ 最佳答案
1. in the case of equal mass, smaller molar mass means greaternumber of mole. more no. of mole will produce more
carbon dioxide. so the answer is A.
2. sodium hydroxide will absorb carbon dioxide.
3. greenish yellow gas can be observed. (chlorine)
Cl2 + H2O< -----> HOCl + HCl
when sodium chloride is added, the equilibrium position
will shift to the left, so chlorine gas will come out.
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