Question

How many water molecules are hydrogen bonded in the following molecular formula?
[Cu(H\(_2\)O)\(_6\)]\(^{2+}\) SO\(_4^{2-}\) \(\cdot\) H\(_2\)O

• A. 4
• B. 3
• C. 1
• D. 5

Hint:

In coordination complexes, water molecules that are not directly bonded to the central metal ion but are held by hydrogen bonding are considered hydrogen-bonded.

Answer 1

The Correct Option is C

Step 1: Understanding the structure of the complex.
In the given molecular formula \([Cu(H_2O)_6]^{2+}\) SO\(_4^{2-}\) \(\cdot\) H\(_2\)O, \) the copper ion (Cu\(^{2+}\)) is surrounded by six water molecules coordinated to it. Additionally, there is one water molecule hydrogen-bonded to the complex, not directly coordinated to the copper ion.

Step 2: Analyzing the options.
(A) 4: This is incorrect. Only one water molecule is hydrogen-bonded, not four.
(B) 3: This is incorrect. Only one water molecule is hydrogen-bonded.
(C) 1: Correct — There is one water molecule hydrogen-bonded to the complex.
(D) 5: This is incorrect. Only one water molecule is hydrogen-bonded.

Step 3: Conclusion.
The correct answer is (C) 1.