Penjelasan:

4.

Volume = 200 ml + 400 ml = 600 ml

• HCl = 0,2 M x 200 ml = 40 Mmol
• HCl = 0,05 M x 400 ml = 20 Mmol

[H^+] = Ka x (mol A/mol G)

= 10^-5 x (40 Mmol:600 ml/20 Mmol:600 ml)

= 10^-5 x 2

= 2 x 10^-5

pH = - log (2 x 10^-5)

= 5 - log 2

= 4,69

5. Diket : NaCN (basa kuat)

HCN (asam lemah)

massa = 3,43 gr

Volume = 1 L

Ka HCN = 7 x 10^-10

Mr NaCN = Ar Na + Ar C + Ar N

= 23 + 12 + 14

= 49 gr/mol

maka,

mol NaCN = massa/Mr

= 3,43 gr / 49 gr/mol

= 0,07 mol

M NaCN = Volume x mol

= 1 L x 0,07 mol

= 0,07 M

[H^+] = √(Ka x M NaCN)

= √(7 x 10^-10 x 0,07 M

= √49 x 10^-12

= 7 x 10^-6

pH = - log (7 x 10^-6)

= 6 - log 7

= 5,15

"maaf no 5 sedikit ragu.