Final answer:
To find the hydroxide ion concentration in a solution made by dissolving 5.00x10−3 mol of HBr in 19.0 L of water, we first calculate the hydronium ion concentration from the dissolved HBr, then use the water ion product constant at 25°C to determine the hydroxide ion concentration, which is 3.8x10−10 M.
Step-by-step explanation:
To calculate the concentration of hydroxide ions (OH-) in a solution where 5.00x10−3 mol of HBr are dissolved in water to make 19.0 L of solution, we must first determine the concentration of hydronium ions (H3O+), as HBr is a strong acid and will dissociate completely in water. The mole ratio of HBr to H3O+ is 1:1, so the concentration of H3O+ in the solution is 5.00x10−3 mol divided by 19.0 L, which equals approximately 2.63x10−5 M. At 25°C, the ion product constant for water (Kw) is 1.0x10−14. We can use this information along with the formula Kw = [H3O+][OH-] to find the concentration of OH-.
w = [HO+][OH−]
1.0x10−14 = (2.63x10−5)([OH−])
[OH−] = 1.0x10−14 / 2.63x10−5 = 3.8x10−10 M
Thus, the concentration of hydroxide ions (OH-) in the solution is 3.8x10−10 M.