Final answer:
To determine the relative strength of acids, we compare their ionization constants (Ka values). The acid with a larger Ka value is stronger. For example, NH4+ is a stronger acid than CH3NH3+ because its conjugate base NH3 has a larger Ka value.
Step-by-step explanation:
In order to determine which acid is stronger, we need to compare their ionization constants (Ka values). The acid with a larger Ka value is stronger. For example, if we compare NH4+ and CH3NH3+, we can look at the Ka values for their conjugate bases NH3 and CH3NH2, respectively. NH3 has a Ka value of 1.8 x 10-5, while CH3NH2 has a Ka value of 2.3 x 10-11. Therefore, NH4+ is the stronger acid because its conjugate base has a larger Ka value.