Final answer:
A brine with a pH of 10 has higher alkalinity compared to one with a pH of 8 because a higher pH indicates a greater ability to neutralize acids.
Step-by-step explanation:
When comparing a brine with a pH of 8 to one with a pH of 10, the alkalinity is higher in the solution with a pH of 10. The pH scale is logarithmic, meaning that each whole number on the scale represents a tenfold increase or decrease in hydrogen ion concentration. Since alkalinity is a measure of the capability of water to neutralize acids, a higher pH value indicates a greater capability, hence higher alkalinity. A substance with a pH value higher than 7 is considered alkaline or basic, and the further the pH value is above 7, the higher the alkalinity.
To understand this further, the equation 2H₂O → H3O+ + OH- illustrates the dissociation of water into hydronium and hydroxide ions. A higher pH indicates a lower concentration of hydronium ions and a higher concentration of hydroxide ions, suggesting greater alkalinity. Thus, a brine with a pH of 10 will have lower hydronium ion concentration and higher alkalinity compared to a brine with a pH of 8.