Final answer:
A Mixed Resin Bed controls the pH of water by releasing hydrogen ions to decrease pH or hydroxide ions to increase pH, ultimately stabilizing the water's pH by forming water molecules which do not change the pH significantly.
Step-by-step explanation:
A Mixed Resin Bed controls the pH of water by involving both cation and anion exchangers. The cation exchangers release hydrogen ions (H+) which can decrease the pH, whereas anion exchangers release hydroxide ions (OH−) which can increase the pH. In a mixed bed, these resins work together to remove both cations and anions, replacing them with H+ and OH− ions which combine to form water (H2O) and thus help in stabilizing the pH of the water without significantly changing it.
Understanding acid-base chemistry is key here. Acids increase the concentration of hydrogen ions in a solution by releasing H+, leading to a lower pH. Bases, on the other hand, accept H+ or, as in the case of hydroxide-based bases, release OH−, which combines with the H+ in the water to form H2O, thereby increasing the pH of the solution.
By both releasing and accepting ions, a mixed resin bed works to keep the water pH stable. If the pH starts to drop, the bed will release more hydroxide ions which bond with the free hydrogen ions. If the pH starts to rise, it will release more hydrogen ions. This balancing act enables mixed resin beds to maintain balance in pH levels.