In which solution of Problem 15.61 is the halide ion concentration 0.1 M, and in which solution is the halide ion concentration much less than 0.1 M? Explain how you know.

Data from Problem 15.61

Two beakers each contain 1 L of water. Then 0.1 mole of HCl gas is dissolved in one beaker, and 0.1 mole of HF gas is dissolved in the other beaker. The HCl solution causes a light bulb to glow intensely, and the HF solution causes the same bulb to glow dimly. Explain these observations.