Many strategies can be used to differentiate between strong and weak acids. Here are some methods:
These results are due to the fact that stronger acids are more reactive, and ionize completely in solution (more H+ ions in solution).
However, in this case, we can look at the bond enthalpies for each compound to determine the weakest acid.
Looking at tabulated data, we can determine that HF has the greatest bond enthalpy of the options. Therefore, HF must be the weakest acid.
It can be useful to memorize common strong acids to face these kinds of questions. These include:
