HCl and HF ionize in water. HCl(aq)  H+(aq) + Cl-(aq) QUESTION: Which figures below best represent aqueous solutions of HF and HCl? A. A for both B. B for both C. HF – B, HCl – A D. HF – A, HCl – B HCl and HF ionize in water. HCl(aq)  H+(aq) + Cl-(aq) HCl is a strong acid. Extent of ionization of HCl is 100%. Extent of ionization of HF is very low. Which figures shown here best represent aqueous solutions of HF and HCl? Is it Figure A for both HCl and HF …Figure B for both Is it Figure B for HF and Figure A for HCl …or is it Figure A for HF and Figure B for HCl CLICK HF and HCl are both acids. These molecular compounds both ionize in water to produce hydrogen ions. CLICK For example, HCl molecules break up into hydrogen ions and chloride ions in water. HCl is a strong acid… This means that the extent of ionization of HCl is 100%. We won’t find any HCl molecules in water. They’re all broken up into hydrogen ions and chloride ions. This is best represented by Figure B --- where the filled circles and unfilled circles are not paired up. Therefore, choices A and C are incorrect. CROSS OUT “HCl – A” in choice C CROSS OUT choice A There are only six known strong acids. HCl is one of them, … HF is not. The extent of ionization of HF is very low… we say that HF is a weak acid. Most of the HF molecules wil remain intact if we put them in water. Therefore, Figure A best represents HF. In this figure, we see pairs of filled and unfilled circles. Therefore, choice B is wrong… CROSS OUT choice B The correct answer is choice D. HF is best represented by Figure A and HCl is best represented by Figure B. PAUSE END RECORDING

Video ID: 5-3-2 © 2008, Project VALUE (Video Assessment Library for Undergraduate Education), Department of Physical Sciences Nicholls State University Author: Glenn V. Lo Narrator: Funded by Louisiana Board of Regents Contract No. LA-DL-SELECT-13-07/08