Several basic operation methods and some experimental operation steps of the third grade chemical physics experimental operation examination

14, commonly used gas generating devices and gas gathering devices:

generating equipment

gathering unit

[Solid (+solid)]

[solid+liquid]

Simple device [solid+liquid] upward drainage method

Downward exhaust method

Air emission method

15, laboratory preparation methods of three gases and their differences;

Gaseous oxygen (O2), hydrogen (H2) and carbon dioxide (CO2).

Drugs potassium chlorate and manganese dioxide or potassium permanganate (KMnO4) or hydrogen peroxide (H2O2) and manganese dioxide (MnO2).

[solid (+solid)] or [solid+liquid] zinc particles (Zn) and dilute sulfuric acid (H2SO4) or hydrochloric acid (HCl)

[solid+liquid] limestone (marble) (CaCO3) and dilute hydrochloric acid (HCl)

[solid+liquid]

Reaction principle 2kmno4 = = k2mno4+MnO2+O2 =

Or 2h2o2 = = 2h2o+O2 = Zn+H2SO4 = ZnSO4+H2 =

Zinc +2 hydrogen chloride = zinc chloride+H2 = calcium carbonate +2 hydrogen chloride = calcium chloride +H2O+ carbon dioxide

Instrument P36 Figure 2- 17 (for example, A of 14)

Or P 1 1 1. Figure 6-10 (b or c of14) p11. Figure 6- 10.

(e.g. b or c of 14) p11. Figure 6- 10

(e.g. b or c of 14)

During the inspection, stick to using Mars to probe into the gas cylinder. If the stick is rekindled, it is oxygen; Otherwise, it is not oxygen that ignites the batten and extends into the bottle. The flame on the batten goes out and the flame at the bottle mouth is light blue. Then the gas is hydrogen, and clear lime water is introduced to see if it becomes turbid. If it is turbid, it is CO2.

Collection method ① Drainage method (insoluble in water) ② Upward air drainage method (denser than air) ① Drainage method (insoluble in water) ② Downward air drainage method (denser than air) ① Upward air drainage method.

(denser than air)

(cannot be collected by drainage method)

Check integrity

(Purification) Use a wooden stick with a spark and lay it flat on the bottle mouth. The stick is rekindled and the oxygen is full, otherwise it will be dissatisfied.

Forward, backward, forward.

Precautions ① Check the air tightness of the equipment.

(When preparing the first drug, you should pay attention to the following matters)

(2) The mouth of the test tube should be slightly inclined downward (to prevent the small water droplets condensed at the mouth of the test tube from flowing back to the bottom of the test tube and breaking the test tube).

(3) When heating, the test tube should be heated evenly first, and then heated in the drug part.

(4) After collecting oxygen by drainage method, first withdraw the catheter and alcohol lamp (to prevent the water in the washbasin from flowing backwards and breaking the test tube) (1) to check the air tightness of the device.

(2) The nozzle of the long-necked funnel should be inserted under the liquid surface;

(3) Before igniting hydrogen, be sure to check the purity of hydrogen (in air, the volume of hydrogen reaches 4%-74.2% of the total volume, and it will explode when ignited. (1) Check the air tightness of the device.

(2) The nozzle of the long-necked funnel should be inserted under the liquid surface;

(3) It cannot be collected by drainage.