Question

Sebanyak 2 gram NaOH (Mr=40) di larutkan dlm air hingga volume larutan menjadi 500mL, pH larutan NaOH tsb adalah????

Answer 1

M = massa/Mr . 1000/v
M = 2/40 . 1000/500
M = 0,1M

NaOH      ->     Na+    +    OH-
0,1M               0,1M         0,1M

[OH-] = 0,1 M
pOH = 1
pH = 14 - pOH
pH = 14 - 1
pH = 13

Answer 2

M=gr/Mr * 1000/v(ml)
  = 2/40 * 1000/500
  = 0,1 M

NaOH -> Na⁺ + OH⁻
0.1mol            0.1mol

pOH = - log [OH⁻]
       = - log [0.1] = 1

pH = 14 - pOH = 14 - 1 = 13

semoga membantu ;)