甲基橙酸碱滴定

用强酸滴定弱碱

Titrations Intermediate (High School) 40 分钟 ~$12.00

目标

以甲基橙为指示剂，用盐酸滴定碳酸钠溶液，测定其浓度，学习适合酸性终点的指示剂选择。

背景

Methyl orange changes color at pH 3.1-4.4 (red to yellow), making it suitable for titrations where the equivalence point is in the acidic range. Sodium carbonate reacts with HCl in a two-step process: first forming NaHCO₃, then NaCl + H₂O + CO₂. Methyl orange detects the second equivalence point.

安全警告

  • HCl is corrosive — avoid skin contact
  • Wear safety goggles throughout
  • Methyl orange is an azo dye — avoid contact with skin

所需PPE

goggles lab_coat

材料

  • Sodium carbonate (Na₂CO₃) (100 mL)
    Unknown concentration
  • Hydrochloric acid (HCl) (100 mL)
    0.1M standardized
  • Methyl orange indicator (5 mL)
    0.1% solution
  • Distilled water (200 mL)

设备

50 mL burette Burette stand and clamp 250 mL Erlenmeyer flask 25 mL pipette Pipette filler White tile

步骤

1

Rinse the burette with HCl solution, then fill it to the 0 mL mark.

3 分钟
2

Pipette 25.0 mL of sodium carbonate solution into the Erlenmeyer flask.

2 分钟
3

Add 2-3 drops of methyl orange indicator. The solution should appear yellow (alkaline).

1 分钟
4

Add HCl slowly while swirling. Watch for the color change from yellow through orange.

8 分钟
5

Near the endpoint, add drop by drop until the solution changes from yellow to a persistent orange/salmon color.

5 分钟
6

Record the volume of HCl used. Repeat for concordant results.

15 分钟
7

Calculate the concentration of Na₂CO₃ considering the 1:2 stoichiometry (Na₂CO₃ + 2HCl → 2NaCl + H₂O + CO₂).

5 分钟

预期结果

The endpoint shows a clear transition from yellow to a persistent orange/salmon color. The volume ratio should confirm the 1:2 molar ratio of carbonate to acid.

清理

Neutralize waste solutions. Rinse all glassware with distilled water. Drain and rinse the burette.

详情

类别
Titrations
难度
Intermediate (High School)
时长
40 分钟
预估费用
$12.00
步骤数
7
材料
4

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Frequently Asked Questions

What is the objective of 甲基橙酸碱滴定?
以甲基橙为指示剂，用盐酸滴定碳酸钠溶液，测定其浓度，学习适合酸性终点的指示剂选择。
How difficult is 甲基橙酸碱滴定?
This experiment is rated as Intermediate (High School). It takes approximately 40 minutes to complete.
What safety precautions are needed for 甲基橙酸碱滴定?
Key safety precautions include: HCl is corrosive — avoid skin contact; Wear safety goggles throughout; Methyl orange is an azo dye — avoid contact with skin.
What materials are needed for 甲基橙酸碱滴定?
The main materials required are: Sodium carbonate (Na₂CO₃), Hydrochloric acid (HCl), Methyl orange indicator, Distilled water.
What results should I expect from 甲基橙酸碱滴定?
The endpoint shows a clear transition from yellow to a persistent orange/salmon color. The volume ratio should confirm the 1:2 molar ratio of carbonate to acid.