电导滴定

用电导率追踪滴定过程

Titrations Advanced (University) 50 分钟 ~$20.00

目标

用电导率测量代替指示剂进行酸碱滴定，并从电导-体积图确定终点。

背景

In a conductometric titration, electrical conductivity of the solution is measured as the titrant is added. Since different ions have different molar conductivities (H+ and OH- are exceptionally mobile), the conductivity changes non-linearly during titration. The endpoint is found where two straight-line segments of the conductivity curve intersect.

安全警告

  • HCl and NaOH are corrosive
  • Wear safety goggles and gloves
  • Keep the conductivity probe away from the magnetic stirrer bar

所需PPE

goggles gloves lab_coat

材料

  • Hydrochloric acid (HCl) (100 mL)
    0.1M
  • Sodium hydroxide (NaOH) (100 mL)
    0.1M
  • Distilled water (200 mL)

设备

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

步骤

1

Pipette 25.0 mL of 0.1M HCl into the beaker. Add 50 mL of distilled water to increase volume for the probe.

3 分钟 Handle HCl carefully
2

Place the beaker on the magnetic stirrer. Insert the conductivity probe and the stir bar.

2 分钟
3

Record the initial conductivity reading. Fill the burette with 0.1M NaOH.

3 分钟
4

Add 1.0 mL of NaOH from the burette. Stir for 30 seconds, then record the conductivity and cumulative volume.

2 分钟
5

Repeat step 4, adding 1.0 mL increments, recording conductivity after each addition. Continue until well past the expected endpoint.

25 分钟
6

Plot conductivity (y-axis) versus volume of NaOH added (x-axis). Identify the two linear regions.

8 分钟
7

Draw best-fit lines for the two regions and find their intersection. This is the endpoint.

5 分钟

预期结果

Conductivity initially decreases as highly mobile H+ ions are replaced by less mobile Na+ ions. After the endpoint, conductivity increases as excess OH- ions accumulate. The V-shaped graph clearly shows the equivalence point.

清理

Remove and rinse the conductivity probe carefully. Neutralize waste solutions before disposal. Rinse all glassware.

详情

类别
Titrations
难度
Advanced (University)
时长
50 分钟
预估费用
$20.00
步骤数
7
材料
3

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Frequently Asked Questions

What is the objective of 电导滴定?
用电导率测量代替指示剂进行酸碱滴定，并从电导-体积图确定终点。
How difficult is 电导滴定?
This experiment is rated as Advanced (University). It takes approximately 50 minutes to complete.
What safety precautions are needed for 电导滴定?
Key safety precautions include: HCl and NaOH are corrosive; Wear safety goggles and gloves; Keep the conductivity probe away from the magnetic stirrer bar.
What materials are needed for 电导滴定?
The main materials required are: Hydrochloric acid (HCl), Sodium hydroxide (NaOH), Distilled water.
What results should I expect from 电导滴定?
Conductivity initially decreases as highly mobile H+ ions are replaced by less mobile Na+ ions. After the endpoint, conductivity increases as excess OH- ions accumulate. The V-shaped graph clearly shows the equivalence point.