メチルオレンジを用いた酸塩基滴定

強酸で弱塩基を滴定する

Titrations Intermediate (High School) 40 分 ~$12.00

目的

メチルオレンジを指示薬として用い、塩酸で炭酸ナトリウム溶液を滴定し、その濃度を決定する。酸性終点に適した指示薬の選択を学ぶ。

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.

安全上の警告

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

必要な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)

器具

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

手順

1

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

3 分
2

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

2 分
3

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

1 分
4

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

8 分
5

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

5 分
6

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

15 分
7

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

5 分

予想される結果

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.

後片付け

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

詳細

カテゴリ
Titrations
難易度
Intermediate (High School)
所要時間
40 分
推定費用
$12.00
ステップ数
7
材料
4

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Frequently Asked Questions

What is the objective of メチルオレンジを用いた酸塩基滴定?
メチルオレンジを指示薬として用い、塩酸で炭酸ナトリウム溶液を滴定し、その濃度を決定する。酸性終点に適した指示薬の選択を学ぶ。
How difficult is メチルオレンジを用いた酸塩基滴定?
This experiment is rated as Intermediate (High School). It takes approximately 40 minutes to complete.
What safety precautions are needed for メチルオレンジを用いた酸塩基滴定?
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 メチルオレンジを用いた酸塩基滴定?
The main materials required are: Sodium carbonate (Na₂CO₃), Hydrochloric acid (HCl), Methyl orange indicator, Distilled water.
What results should I expect from メチルオレンジを用いた酸塩基滴定?
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.