---
title: "A student investigating the molecular factors that govern proton donation compiles the bond dissociation enthalpies shown below.  | Hydrogen halide | Bond dissociation enthalpy of \\(\\text{H-X}\\) | |—|—:| | \\(\\text{HCl}\\) | \\(431\\ \\text{kJ/mol}\\) | | \\(\\text{HBr}\\) | \\(366\\ \\text{kJ/mol}\\) | | \\(\\text{HI}\\) | \\(299\\ \\text{kJ/mol}\\) |  Which choice gives the hydrogen halides in order of greatest to least acid strength and provides the best justification?"
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url: "https://nerd-notes.com/ubq/119496/"
date_modified: "2026-08-19T12:40:45+00:00"
---

# A student investigating the molecular factors that govern proton donation compiles the bond dissociation enthalpies shown below.

| Hydrogen halide | Bond dissociation enthalpy of \(\text{H-X}\) |
|—|—:|
| \(\text{HCl}\) | \(431\ \text{kJ/mol}\) |
| \(\text{HBr}\) | \(366\ \text{kJ/mol}\) |
| \(\text{HI}\) | \(299\ \text{kJ/mol}\) |

Which choice gives the hydrogen halides in order of greatest to least acid strength and provides the best justification?

A student investigating the molecular factors that govern proton donation compiles the bond dissociation enthalpies shown below.

| Hydrogen halide | Bond dissociation enthalpy of \(\text{H-X}\) |
|---|---:|
| \(\text{HCl}\) | \(431\ \text{kJ/mol}\) |
| \(\text{HBr}\) | \(366\ \text{kJ/mol}\) |
| \(\text{HI}\) | \(299\ \text{kJ/mol}\) |

Which choice gives the hydrogen halides in order of greatest to least acid strength and provides the best justification?

- **A.** \(\text{HCl} > \text{HBr} > \text{HI}\), because a greater \(\text{H-X}\) bond dissociation enthalpy makes release of \(\text{H}^+\) more favorable.
- **B.** \(\text{HCl} > \text{HI} > \text{HBr}\), because the greater polarity of \(\text{H-Cl}\) makes \(\text{HCl}\) strongest, while the lower bond dissociation enthalpy of \(\text{H-I}\) makes \(\text{HI}\) stronger than \(\text{HBr}\).
- **C.** \(\text{HI} > \text{HBr} > \text{HCl}\), because iodine is more electronegative than bromine and chlorine, making \(\text{H-I}\) the most polar bond.
- **D.** \(\text{HI} > \text{HBr} > \text{HCl}\), because the decreasing \(\text{H-X}\) bond dissociation enthalpy makes the bond easier to disrupt during proton donation.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/119496/*