醋酸钠的放热结晶

测量瞬间结晶过程中释放的热量

Thermochemistry Intermediate (High School) 30 分钟 ~$8.00

目标

用量热法定量测定过饱和醋酸钠结晶过程中释放的热量。

背景

When supersaturated sodium acetate crystallizes, it releases stored energy as heat. By triggering crystallization inside a calorimeter and measuring the temperature rise, the enthalpy of crystallization can be determined. This is the same principle used in reusable hand warmers.

安全警告

  • Hot solution during preparation
  • Crystallization releases heat — container gets warm

所需PPE

goggles

材料

  • Sodium acetate trihydrate (80 g)
  • Distilled water (150 mL)

设备

Polystyrene cup calorimeter Hot plate Thermometer Beaker (250 mL) Stirring rod

步骤

1

Dissolve 80 g sodium acetate trihydrate in 20 mL water by heating to about 70°C. Stir until clear.

8 分钟 Handle hot solution carefully
2

Pour the solution into the polystyrene cup calorimeter. Allow to cool undisturbed to room temperature.

15 分钟
3

Record the temperature of the supersaturated solution.

1 分钟
4

Add a single small crystal of sodium acetate to trigger crystallization. Immediately stir gently and record temperature every 15 seconds.

3 分钟
5

Record the maximum temperature reached.

1 分钟
6

Calculate the heat released: q = mcΔT. Determine ΔH of crystallization per mole.

5 分钟

预期结果

Temperature should rise 15-25°C above room temperature. The enthalpy of crystallization is approximately -19.7 kJ/mol for sodium acetate trihydrate. Measured values should be within 20% of this.

清理

The sodium acetate can be remelted and reused. Rinse the calorimeter. Non-toxic — can go down the drain.

详情

类别
Thermochemistry
难度
Intermediate (High School)
时长
30 分钟
预估费用
$8.00
步骤数
6
材料
2

更多实验

冰的熔化焓 25 min 冷敷包的化学原理 20 min 吸热反应演示 20 min 咖啡杯量热法 40 min 弹式量热计模拟 45 min 溶解并非总是放热的 25 min 赫斯定律验证 60 min 金属的比热容 40 min 镁的燃烧热 50 min

Frequently Asked Questions

What is the objective of 醋酸钠的放热结晶?
用量热法定量测定过饱和醋酸钠结晶过程中释放的热量。
How difficult is 醋酸钠的放热结晶?
This experiment is rated as Intermediate (High School). It takes approximately 30 minutes to complete.
What safety precautions are needed for 醋酸钠的放热结晶?
Key safety precautions include: Hot solution during preparation; Crystallization releases heat — container gets warm.
What materials are needed for 醋酸钠的放热结晶?
The main materials required are: Sodium acetate trihydrate, Distilled water.
What results should I expect from 醋酸钠的放热结晶?
Temperature should rise 15-25°C above room temperature. The enthalpy of crystallization is approximately -19.7 kJ/mol for sodium acetate trihydrate. Measured values should be within 20% of this.