Category name

First, the purpose of the experiment:

1, master the operation skills of dissolution, filtration and evaporation.

2. Understand the chemical principle of separating mixtures by filtration.

Second, the experimental principle:

The crude salt contains insoluble impurities such as precipitate. Insoluble impurities can be removed by dissolution and filtration, and then evaporated to obtain pure refined salt.

Three, experimental instruments and drugs:

Drugs: crude salt, water

Equipment: tray balance, measuring cylinder, beaker, glass rod, medicine spoon, funnel, iron shelf (with iron ring), evaporating dish, alcohol lamp, crucible pliers, rubber-tipped dropper, filter paper and matches.

Fourth, the experimental steps:

1, dismissed

Weigh 5g of raw salt with a tray balance. Measure about 10 ml of water with a measuring cylinder and pour it into a beaker. Take a spoonful of raw salt with a key and add it to the water. Stir with a glass rod while adding it until the raw salt no longer dissolves. ..

Step 2: Filter.

Fold the filter paper into a cone, put it into a funnel, and then use a glass rod to guide the solution down the rod.

Step 3 evaporate

Pour the clarified filtrate into an evaporating dish. Place the evaporating dish on the iron ring of the iron frame and heat it with alcohol lamp. While stirring the filtrate with a glass rod. When a large number of solids appear in the evaporating dish, stop heating.

4. Transfer the filter residue to paper with a glass rod, weigh it and recycle it to the designated container. Compare the state of salt before and after purification.

Experimental summary of verb (abbreviation of verb);

In this experiment, * * * has used the glass rod three times, and its function is _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _