盐与沙的分步结晶

利用溶解度差异分离混合物

Crystallization Beginner (Middle School) 35 分钟 ~$3.00

目标

通过分步结晶分离盐和沙的混合物，演示溶解、过滤和蒸发结晶的过程。

背景

This classic separation technique exploits the fact that salt dissolves in water while sand does not. The mixture is dissolved in hot water, filtered to remove sand, and then the salt is recovered by evaporation. This is fundamentally how salt has been harvested from seawater for millennia.

安全警告

  • Handle hot evaporating dish with tongs
  • Do not heat to dryness too rapidly — spattering risk

所需PPE

goggles

材料

  • Salt-sand mixture (10 g)
    Pre-mixed approximately 50:50
  • Distilled water (100 mL)

设备

250 mL beaker Filter paper Funnel Evaporating dish Hot plate Stirring rod Analytical balance

步骤

1

Weigh 10 g of the salt-sand mixture and record the mass.

2 分钟
2

Add the mixture to 100 mL of warm water in the beaker. Stir for 5 minutes to dissolve all the salt.

5 分钟
3

Filter the mixture through filter paper. The sand remains on the filter; the salt solution passes through.

5 分钟
4

Rinse the sand on the filter with a small amount of distilled water. Dry the sand and weigh it.

5 分钟
5

Pour the filtrate into the evaporating dish. Heat gently on the hot plate to evaporate the water.

12 分钟 Remove from heat before completely dry
6

Once dry, weigh the recovered salt. Calculate the percentage of each component.

3 分钟
7

Compare the total recovered mass with the initial mass. Calculate percent recovery.

3 分钟

预期结果

The total mass of recovered salt + sand should be close to the original 10 g (typically 90-98% recovery). Some loss occurs during transfer and on filter paper. The separated components should be visually distinct.

清理

Salt solution can go down the drain. Sand can go in the trash. Rinse all glassware.

详情

类别
Crystallization
难度
Beginner (Middle School)
时长
35 分钟
预估费用
$3.00
步骤数
7
材料
2

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Frequently Asked Questions

What is the objective of 盐与沙的分步结晶?
通过分步结晶分离盐和沙的混合物，演示溶解、过滤和蒸发结晶的过程。
How difficult is 盐与沙的分步结晶?
This experiment is rated as Beginner (Middle School). It takes approximately 35 minutes to complete.
What safety precautions are needed for 盐与沙的分步结晶?
Key safety precautions include: Handle hot evaporating dish with tongs; Do not heat to dryness too rapidly — spattering risk.
What materials are needed for 盐与沙的分步结晶?
The main materials required are: Salt-sand mixture, Distilled water.
What results should I expect from 盐与沙的分步结晶?
The total mass of recovered salt + sand should be close to the original 10 g (typically 90-98% recovery). Some loss occurs during transfer and on filter paper. The separated components should be visually distinct.