Question

A 19.45 gram sample of copper is heated in the presence of excess iodine. A metal iodide is formed with a mass of 58.30 g. Determine the empirical formula of the metal iodide.

Answer 1

Answer: The empirical formula for the given compound is $CuI$

Explanation : Given,

Mass of Cu= 19.45 g

Mass of metal iodide = 58.30 g

Now we have to calculate the mass of iodide.

Mass of I = Mass of metal iodide - Mass of Cu

Mass of I = 58.30 - 19.45

Mass of I = 38.85 g

To formulate the empirical formula, we need to follow some steps:

Step 1: Converting the given masses into moles.

Moles of Cu =$\frac{\text{Given mass of Cu}}{\text{Molar mass of Cu}}=\frac{19.45g}{63.54g/mole}=0.306moles$

Moles of I = $\frac{\text{Given mass of I}}{\text{Molar mass of I}}=\frac{38.85g}{126.9g/mole}=0.306moles$

Step 2: Calculating the mole ratio of the given elements.

For the mole ratio, we divide each value of the moles by the smallest number of moles calculated which is 0.0306 moles.

For Cu = $\frac{0.306}{0.306}=1$

For I = $\frac{0.306}{0.306}=1$

Step 3: Taking the mole ratio as their subscripts.

The ratio of Cu : I = 1 : 1

Hence, the empirical formula for the given compound is $Cu_1I_1=CuI$