Question

List the hydrogen halide acids in decreasing order of reactivity in the following reaction
$R-OH+HX\to RX+H_{2}O$

• A. HI > HBr > HCl > HF
• B. HBr > HI > HCl > HF
• C. HI > HCl > HBr > HF
• D. HI > HF > HBr > HI

Answer 1

Answer: (A)

The relative rate follows same order as of acidity (HI > HBr > HCl > HF) and the nucliophilicity of their conjugate anion, $X^{-}(I^{-}>B{r}^{-}>C{l}^{-}>F^{-})$ .