Answer :
Answer
K₂CrO₅
Explanation
Given:
Mass of potassium = 0.890 g
Mass of chromium = 0.590 g
Mass of oxygen = 0.727 g
What to find:
The empirical formula of the compound.
Step-by-step solution:
Step 1: Find the number of moles for each element by dividing the mass present with the relative mass of the atom.
The mole formula is given by:
[tex]Moles=\frac{Mass}{Molar\text{ }mass}[/tex]Molar mass of K = 39.098 g/mol
Molar mass of Cr = 51.996 g/mol
Molar mass of O = 15.999 g/mol
So,
[tex]\begin{gathered} Moles\text{ }of\text{ }K=\frac{0.890\text{ }g}{39.098\text{ }g\text{/}mol}=0.02\text{ }mol\text{ }K \\ \\ Moles\text{ }of\text{ }Cr=\frac{0.590\text{ }g}{51.996\text{ }g\text{/}mol}=0.01\text{ }mol\text{ }Cr \\ \\ Moles\text{ }of\text{ }O=\frac{0.727\text{ }g}{15.999\text{ }g\text{/}mol}=0.05\text{ }mol\text{ }O \end{gathered}[/tex]Step 2: Divide each number of moles by the lowest one, in this case
0.01.
[tex]\begin{gathered} \frac{0.02\text{ }mol\text{ }K}{0.01}=2\text{ }mol\text{ }K \\ \\ \frac{0.01\text{ }mol\text{ }Cr}{0.01}=1\text{ }mol\text{ }Cr \\ \\ \frac{0.05\text{ }mol\text{ }O}{0.01}=5\text{ }mol\text{ }O \end{gathered}[/tex]The final step is to use the mole ratio in step 2 to write the empirical formula of the compound.
The empirical formula of the compound is:
[tex]K_2CrO_5[/tex].