Question

Compare the ph of 0.1 m na2co3 and 0.1 m nahco3. select the statements that explain the difference. na2co3 is a stronger base. nahco3 is a stronger base. na2co3 puts more oh- ion into solution.

Answer 1

na2co3 is a stronger base

na2co3 puts more oh- ion into solution

Step-by-step explanation:

Step 1: Calculate the pH of 0.1 M Na2CO3

`Na_(2) CO_(3) ----- 2Na^(+) + CO_(3) ^(2-) \\\\CO_(3)^(2-)  + H_(2) O ------HCO_(3)^(-)  + OH^(-) \\`

Kb value for Na2CO3 = 2.1 * 10⁻⁴

Set up an ICE table

CO_{3}^{2-} + H_{2} O ------HCO_{3}^{-} + OH^{-} \\[/tex]

I 0.1 - - -

C -x +x +x

E (0.1-x) x x

`Kb = ([HCO3-][OH-])/([CO3^(2-]) ) \\\\Kb = (x^(2) )/((0.1-x)) \\\\2.1*10^(-4) = (x^(2) )/((0.1-x)) \\\\x = [OH-] = 0.00458 M\\\\pOH = -log[OH-] = -log(0.00458) = 2.33\\\\pH = 14 - 2.33 = 11.66`

Step 2: Calculate pH of 0.1M NaHCO3

NaHCO3 is amphiprotic i,e it acts as an acid and base

`NaHCO3 ------- Na+ + HCO3-\\\\HCO3- ------ H+ + CO3^(2-)  (acts as acid, H+ released)\\\\HCO3= + H2O ------- H2CO3- + OH- (acts as base, OH- released)\\\\`

For amphiprotic systems:

`[H+] = √(Ka1 * Ka2) \\\\For H2CO3:\\Ka1 = 4.5 * 10^(-7) \\Ka2 = 4.8 * 10^(-11) \\\\[H+] = √((4.5*10-7 * 4.8*10-11) = 4.65*10-9\\pH = -log[H+] = 8.33`

Conclusion:

pH of 0.1 M Na2CO3 = 11.66

pH of 0.1 M NaHCO3 = 8.33

Higher the pH , more basic the solution. Hence, Na2CO3 is a stronger base than NaHCO3

Answer 2

Na₂CO₃ is a stronger base while
Na₂CO₃ puts more OH- ion into solution
The strongest base is [H₊]= 10 - 12
The strongest acid is PH = 0.5
If an acid is added to neutral water the H₊
will increase but when an acid added to neutral water
the OH⁻ will decrease.