フェノールフタレインを用いた酸塩基滴定

標準塩基溶液を使って酸の濃度を決定する

Titrations Intermediate (High School) 45 分 ~$15.00

目的

フェノールフタレインを指示薬として用い、標準化した水酸化ナトリウム溶液で未知濃度の塩酸溶液を滴定し、濃度を決定する。

背景

This classic acid-base titration demonstrates stoichiometric neutralization. HCl reacts with NaOH in a 1:1 molar ratio. Phenolphthalein turns pink above pH 8.2, providing a clear endpoint. Accurate burette technique and multiple trials are essential for reliable results.

安全上の警告

  • NaOH is corrosive — avoid skin and eye contact
  • HCl is corrosive — handle with care
  • Wear safety goggles throughout
  • Wash any spills immediately with water

必要なPPE

goggles gloves lab_coat

材料

  • Hydrochloric acid (HCl) (100 mL)
    Unknown concentration
  • Sodium hydroxide (NaOH) (100 mL)
    0.1M standardized
  • Phenolphthalein indicator (5 mL)
    1% in ethanol
  • Distilled water (500 mL)
    For rinsing

器具

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

手順

1

Rinse the burette with a small amount of NaOH solution, then fill it to the 0 mL mark. Record the exact starting volume.

5 分 Handle NaOH carefully
2

Using the pipette and filler, transfer exactly 25.0 mL of the unknown HCl solution into the Erlenmeyer flask.

3 分
3

Add 2-3 drops of phenolphthalein indicator to the flask. The solution should remain colorless (acidic).

1 分
4

Place the flask on the white tile under the burette. Begin adding NaOH slowly while swirling the flask continuously.

5 分
5

As the endpoint approaches (pink color lingers longer), add NaOH drop by drop until a permanent pale pink color persists for 30 seconds.

5 分
6

Record the final burette reading. Calculate the volume of NaOH used.

2 分
7

Repeat the titration at least two more times for concordant results (within 0.10 mL).

15 分
8

Calculate the concentration of HCl using: C(HCl) = C(NaOH) x V(NaOH) / V(HCl).

5 分

予想される結果

The endpoint should show a clear transition from colorless to a persistent pale pink. Concordant titre values (within 0.10 mL) indicate good technique. The calculated concentration should match the expected value within experimental error.

後片付け

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

詳細

カテゴリ
Titrations
難易度
Intermediate (High School)
所要時間
45 分
推定費用
$15.00
ステップ数
8
材料
4

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Frequently Asked Questions

What is the objective of フェノールフタレインを用いた酸塩基滴定?
フェノールフタレインを指示薬として用い、標準化した水酸化ナトリウム溶液で未知濃度の塩酸溶液を滴定し、濃度を決定する。
How difficult is フェノールフタレインを用いた酸塩基滴定?
This experiment is rated as Intermediate (High School). It takes approximately 45 minutes to complete.
What safety precautions are needed for フェノールフタレインを用いた酸塩基滴定?
Key safety precautions include: NaOH is corrosive — avoid skin and eye contact; HCl is corrosive — handle with care; Wear safety goggles throughout.
What materials are needed for フェノールフタレインを用いた酸塩基滴定?
The main materials required are: Hydrochloric acid (HCl), Sodium hydroxide (NaOH), Phenolphthalein indicator, Distilled water.
What results should I expect from フェノールフタレインを用いた酸塩基滴定?
The endpoint should show a clear transition from colorless to a persistent pale pink. Concordant titre values (within 0.10 mL) indicate good technique. The calculated concentration should match the expected value within experimental error.