Question

\(1.5g\) of \(CdCl_2\) was found to contain \(0.9g\) of Cd. Calculate the atomic weight of Cd.

• A. \(118\)
• B. \(112\)
• C. \(105\)
• D. \(53.25\)

Hint:

Use fraction: \(\frac{\text{mass of element}}{\text{mass of compound}} = \frac{\text{atomic mass}}{\text{molar mass}}\).

Answer 1

The Correct Option is C

Step 1: Determine mass fraction of Cd in CdCl\(_2\).
\[ \text{Fraction of Cd} = \frac{0.9}{1.5} = 0.6 \]
Step 2: Use formula mass relation.
Let atomic mass of Cd = \(M\).
Molar mass of \(CdCl_2\):
\[ M + 2(35.5) = M + 71 \]
Mass fraction:
\[ \frac{M}{M+71} = 0.6 \]
Step 3: Solve for \(M\).
\[ M = 0.6(M+71) \Rightarrow M = 0.6M + 42.6 \]
\[ 0.4M = 42.6 \Rightarrow M = 106.5 \approx 105 \]
Final Answer:
\[ \boxed{105} \]