moles NaOH = grams/molar mass
M = moles NaOH/L soln.
(OH^-) = M NaOH
pOH = -log(OH^-)
Use pH + pOH = pKw = 14 to convert pOH to pH.
Then convert pH to (H^+) by
pH = -log(H^+).
A solution of NaOH(aq) contains 6.2 g of NaOH(s) per 100.0 mL of solution. Calculate the pH and the pOH of the solution at 25 °C.
3 answers
i didn't know ph could be greater than 14 and poh less than 0
It can.
For example, if M HCl = 0.1M, then (H^+) = 0.1 and pH = 1
If M HCl = 1.0, then (H^+) = 1.0M and pH = -log(1.0) = 0
If M HCl = 10.0, then (H^+) = 10.0M and pH = -log(10) = -log(1) = -1.
We usually work with pH values for solns in the 0.1 and smaller range; therefore, the pH is always greater than zero and positive. In fact, when the pH scale was first devised, the negative sign was put in the definition (pH = -log(H^+) for the expressed purpose of making the number a positive number since the log of numbers less than 1 are negative.
For example, if M HCl = 0.1M, then (H^+) = 0.1 and pH = 1
If M HCl = 1.0, then (H^+) = 1.0M and pH = -log(1.0) = 0
If M HCl = 10.0, then (H^+) = 10.0M and pH = -log(10) = -log(1) = -1.
We usually work with pH values for solns in the 0.1 and smaller range; therefore, the pH is always greater than zero and positive. In fact, when the pH scale was first devised, the negative sign was put in the definition (pH = -log(H^+) for the expressed purpose of making the number a positive number since the log of numbers less than 1 are negative.
5 answers