胃药片逆滴定

测量商业抗酸药的酸中和能力

Titrations Intermediate (High School) 60 分钟 ~$12.00

目标

用逆滴定法测定商业抗酸药片的酸中和能力。

背景

Direct titration of antacid is impractical because the active ingredients dissolve slowly. In a back titration, excess acid is added to the antacid, allowed to react fully, and the remaining unreacted acid is titrated with base. The difference reveals how much acid the antacid neutralized.

安全警告

  • HCl and NaOH are corrosive
  • Wear safety goggles and gloves
  • Use caution with the hot plate

所需PPE

goggles gloves lab_coat

材料

  • Antacid tablets (2 tablets)
    CaCO₃-based, like Tums
  • Hydrochloric acid (HCl) (200 mL)
    0.5M
  • Sodium hydroxide (NaOH) (100 mL)
    0.5M standardized
  • Phenolphthalein indicator (5 mL)
  • Distilled water (200 mL)

设备

50 mL burette Burette stand and clamp 250 mL Erlenmeyer flask 25 mL pipette Mortar and pestle Analytical balance Hot plate

步骤

1

Weigh the antacid tablet accurately on the analytical balance and record the mass.

3 分钟
2

Crush the tablet into a fine powder using the mortar and pestle.

3 分钟
3

Transfer the powder to the Erlenmeyer flask. Add exactly 50.0 mL of 0.5M HCl using the pipette.

3 分钟 Handle HCl carefully
4

Gently heat the mixture on the hot plate for 10 minutes to ensure complete reaction of the antacid.

12 分钟 Do not boil vigorously
5

Allow the solution to cool to room temperature.

5 分钟
6

Add 2-3 drops of phenolphthalein indicator.

1 分钟
7

Fill the burette with 0.5M NaOH. Titrate the excess HCl until a persistent pale pink color appears.

10 分钟
8

Record the volume of NaOH used. Calculate moles of excess HCl, then moles neutralized by the antacid.

5 分钟

预期结果

A typical CaCO₃-based antacid tablet (500 mg) should neutralize approximately 10 mmol of HCl. The mass of CaCO₃ calculated should approximate the labeled amount on the package.

清理

Neutralize all waste solutions before disposal. Rinse glassware thoroughly. Clean the mortar and pestle.

详情

类别
Titrations
难度
Intermediate (High School)
时长
60 分钟
预估费用
$12.00
步骤数
8
材料
5

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Frequently Asked Questions

What is the objective of 胃药片逆滴定?
用逆滴定法测定商业抗酸药片的酸中和能力。
How difficult is 胃药片逆滴定?
This experiment is rated as Intermediate (High School). It takes approximately 60 minutes to complete.
What safety precautions are needed for 胃药片逆滴定?
Key safety precautions include: HCl and NaOH are corrosive; Wear safety goggles and gloves; Use caution with the hot plate.
What materials are needed for 胃药片逆滴定?
The main materials required are: Antacid tablets, Hydrochloric acid (HCl), Sodium hydroxide (NaOH), Phenolphthalein indicator, Distilled water.
What results should I expect from 胃药片逆滴定?
A typical CaCO₃-based antacid tablet (500 mg) should neutralize approximately 10 mmol of HCl. The mass of CaCO₃ calculated should approximate the labeled amount on the package.