HKCEE 1999 Q2

2009-05-21 6:25 pm

One mole of calcium bromide contains

A. 1 mole of molecules
B. 2 moles of cations
C. 2 moles of cations
D. 3 moles of atoms

pls explain in eng!
thanks a lot!!!

回答 (1)

老爺子

2009-05-21 7:26 pm

✔ 最佳答案

The answer is C.

Option C should be "C. 2 moles of anions"

Calcium bromide is an ionic compound. Refer to its chemical formula CaBr2. Each mole of CaBr2 contains 1 mole of Ca2+ cations and 2 moles of Br- anions.

A is incorrect.
CaBr2 is an ionic compound, which contains ions but NOT molecules.

B is incorrect.
Each mole of CaBr2 contains 1 mole of Ca2+ cations, but NOT 2 moles.

C is correct.
Each mole of CaBr2 contains 2 moles of Br- anions.

A is incorrect.
CaBr2 is an ionic compound, which contains ions but NOT atoms.
=

2009-05-21 11:27:01 補充：
The last second line should be "D is incorrect".

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