Explain the chemistry behind chromyl chloride test.
The procedure given by your friend is absolutely correct
Chromyl chloride test is done for detecting the presence of Cl- ions of ionic compounds.
The equation for the test is as follow:
K 2 Cr 2 O 7 + 4Cl- + 6H 2 SO 4 → 2CrO 2 Cl 2 + 2KHSO 4 + 4HSO 4 -+3H 2 O