What makes an acid strong or weak? The first thing on our properties of acids list is that acids produce hydrogen ions in water. This is called ionization or dissociation. The strength of the acid depends on the number of hydrogen ions released. The higher the number of hydrogen ions in water, then the stronger the acid. The strongest acids completely ionize in water and are strong electrolyte.

Watch the animation of HCl and HF dissolving. Answer the following questions during the animation.

1. Which is the stronger acid? HCl or HF Interactive popup. Assistance may be required. Check Your Answer HCL Close
2. Which is a strong electrolyte? HCl or HF Interactive popup. Assistance may be required. Check Your Answer HCL Close
3. To what degree does HCl ionize (break apart)? Interactive popup. Assistance may be required. Check Your Answer Completely (100%) Close
4. To what degree does HF ionize (break apart)? Interactive popup. Assistance may be required. Check Your Answer A limited extent (very little) Close
5. What happens to the amount of HCl in solution as the amount of H+ and Cl- increases? Interactive popup. Assistance may be required. Check Your Answer it decreases Close

Strength of the acid is not to be confused with dilution or concentration (molarity). You can have a dilute solution of a very strong acid. If 99% of the hydrogen ions in an acid are ionized when in water, the acid is considered to be strong. There are six acids that meet this criteria: