Class: Name: Classmate: Experimental Time: Experimental Purpose: 1. Practice preparing a solution with a certain substance concentration; 2. Deepen the understanding of the concepts of quantity and concentration of substances; 3. Practice the use of the volumetric flask.

Experimental instruments: tray balance, small beaker, medicine spoon, 100ml volumetric flask, rubber-tipped dropper, glass rod, measuring cylinder Experimental drugs: NaCl solid, distilled water.

Experiment (1): Prepare 1 00 ml of 0.50 mol/L NaCl solution (1) Experimental steps:

1, calculation: the required mass of NaCl solid is.

2. Weighing: When weighing with a pallet balance, the mass of the weighed NaCl solid is.

3. Dissolution: put the weighed NaCl solid into a jar and measure distilled water with a measuring cylinder to dissolve it. 4. Liquid transfer: the solution is discharged and injected into the volumetric flask. 5. Washing: Wash the inner wall of the beaker several times with a small amount of distilled water, and inject the washing liquid into the volumetric flask. 6. Shake: Shake the volumetric flask gently to make the solution mix evenly.

7. Constant volume: pour distilled water into the volumetric flask and drop the distillation below the scale line of the volumetric bottleneck.

Here comes the water.

8. Shake upside down: cover the cork and turn it upside down repeatedly. 9. Bottle: Pour the prepared reagent into reagent bottle and label it.

Experiment (2): Prepare 100 ml of 0. 10 mol/l NaCl solution with 0.50 mol/l NaCl solution (2) Experimental steps:

1. calculation: calculate the required volume of 0.50 mol/L NaCl solution in milliliter (mL). 2. Measurement: Measure 0.50 mol/L NaCl solution with a measuring cylinder.

3. Dissolve: Pour the measured NaCl solution into a jar and measure distilled water with a measuring cylinder to dissolve. 4. Liquid transfer: the solution is discharged and injected into the volumetric flask. 5. Washing: Wash the inner wall of the beaker several times with a small amount of distilled water, and inject the washing liquid into the volumetric flask. 6. Shake: Shake the volumetric flask gently to make the solution mix evenly.

7. Constant volume: inject distilled water into the volumetric flask and drop distillation below the scale line of the volumetric bottleneck.

Here comes the water.

8. Shake upside down: cover the cork and turn it upside down repeatedly. 9. Bottle: Pour the prepared reagent into reagent bottle and label it.

Discuss and fill in the blanks.

1, volumetric flask is often used to prepare a certain volume of solution with accurate concentration. The volumetric flask is marked with, ml, ml, ml, ml, etc. 2. What is the reason for washing this step?

3. Why should the prepared solution be poured into reagent bottle from the volumetric flask?

4. In the process of constant volume, the liquid is accidentally dropped on the calibration line, and the experiment fails, so it should be poured out and reconstituted. Why?