Curva de Titulação de pH

Plotagem de uma curva completa de titulação ácido-base com medidor de pH

Titrations Intermediate (High School) 50 min ~$15,00

Objetivo

Registrar medições de pH durante uma titulação ácido-base e construir uma curva de titulação em forma de S mostrando o ponto de equivalência e as regiões tampão.

Contexto

A pH titration curve provides far more information than an indicator-based titration. The S-shaped curve reveals the buffer region, half-equivalence point (where pH equals pKa for weak acids), and the sharpness of the equivalence point. This experiment compares the curves of strong and weak acids.

Avisos de segurança

  • HCl and NaOH are corrosive
  • Wear safety goggles and gloves
  • Handle the pH electrode carefully — it is fragile

EPI necessário

goggles gloves lab_coat

Materiais

  • Hydrochloric acid (HCl) (50 mL)
    0.1M
  • Sodium hydroxide (NaOH) (100 mL)
    0.1M
  • pH buffer solutions (3 bottles)
    pH 4, 7, 10 for calibration
  • Distilled water (200 mL)

Equipamentos

50 mL burette Burette stand and clamp 250 mL beaker pH meter with electrode Magnetic stirrer 25 mL pipette Graph paper

Procedimento

1

Calibrate the pH meter using the three buffer solutions (pH 4, 7, 10).

5 min Handle pH electrode gently
2

Pipette 25.0 mL of 0.1M HCl into the beaker. Record the initial pH.

3 min
3

Fill the burette with 0.1M NaOH. Record the initial volume.

3 min
4

Add NaOH in 1.0 mL increments, recording the pH after each addition. When pH changes rapidly, switch to 0.2 mL increments.

25 min
5

Continue adding NaOH until the pH is above 12. Add a few more points past the equivalence point.

5 min
6

Plot pH (y-axis) versus volume of NaOH (x-axis) to construct the titration curve.

7 min

Resultados esperados

The curve should show a characteristic S-shape: slowly rising pH initially, a steep jump around the equivalence point (pH 7 for strong acid-strong base), then leveling off at high pH. The equivalence point volume should be approximately 25 mL.

Limpeza

Rinse the pH electrode and store in storage solution. Neutralize waste before disposal. Rinse all glassware.

Detalhes

Categoria
Titrations
Dificuldade
Intermediate (High School)
Duração
50 min
Custo estimado
$15,00
Passos
6
Materiais
4

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Frequently Asked Questions

What is the objective of Curva de Titulação de pH?
Registrar medições de pH durante uma titulação ácido-base e construir uma curva de titulação em forma de S mostrando o ponto de equivalência e as regiões tampão.
How difficult is Curva de Titulação de pH?
This experiment is rated as Intermediate (High School). It takes approximately 50 minutes to complete.
What safety precautions are needed for Curva de Titulação de pH?
Key safety precautions include: HCl and NaOH are corrosive; Wear safety goggles and gloves; Handle the pH electrode carefully — it is fragile.
What materials are needed for Curva de Titulação de pH?
The main materials required are: Hydrochloric acid (HCl), Sodium hydroxide (NaOH), pH buffer solutions, Distilled water.
What results should I expect from Curva de Titulação de pH?
The curve should show a characteristic S-shape: slowly rising pH initially, a steep jump around the equivalence point (pH 7 for strong acid-strong base), then leveling off at high pH. The equivalence point volume should be approximately 25 mL.