Instruments: Cape generator, iron frame (iron clip), beaker, large test tube, rubber stopper, water stop clip, electronic lighter, capillary steel tube, rubber wire, medical plastic syringe, infusion set, etc.
Drugs: potassium permanganate, concentrated hydrochloric acid, zinc granules, dilute hydrochloric acid, saturated salt solution, purple litmus test solution, NaOH solution, etc.
Before the experiment, be sure to check the air tightness of the device and then charge it.
Experimental principle
H2+Cl2==2HCl (under ignition condition)
Experimental device and assembly instructions
The experimental device is shown in Figure 2.
Assembly instructions:?
(1) Select a rubber stopper that matches the orifice of a large test tube with a specification of 30×200 mm, punch three small holes with appropriate size on it, and then install them in turn, with a diameter of 1 mm and a length of about 12 cm, as shown in Figure 2.
Left and right capillary steel pipes, thin glue line about 14 cm long and a three-way infusion set interface. Guide the rubber with a small piece of hard plastic board.
The wire is fixed at a distance of about 0.5 cm from one side of the capillary steel tube, so that the end of the wire is located at the end of the capillary steel tube, and is inclined upward by 30 degrees at an angular distance of about 0.4 cm.
Location.
(2) One end of the interface of the three-way infusion set is connected with a large test tube. The other two ports, one is connected with the syringe through the infusion tube, and the other is connected with the infusion tube through a water stop clip and a thin glass tube, and the glass tube is inserted into a small beaker filled with purple litmus test solution.
(3) Saw off the lower part of the electronic lighter with plastic casing and no fuel with hacksaw, try to remove the small metal part on the lower side of the valve for controlling gas flow rate and its wrapped white conduit on the lighter, cut off the part where the white conduit is exposed from the metal casing, tie a small hole in the remaining part with a pin, then connect the small end of the small metal piece wrapped with the white conduit with the fine infusion tube, and reinstall it in the corresponding part of the lighter, and pay attention to sealing the fine infusion tube with the small hole at the bottom of the lighter.
(4) Connect the upper opening of the valve of the electronic lighter with the capillary steel tube on the rubber plug with a thin infusion tube, connect the lead wire of the lighter with the metal lead wire on the rubber plug, and seal the joint with insulating tape.
(5) The thin infusion tube at the bottom of the electronic lighter tries to connect with the Kipp generator.
Experimental operation
(1) Connect the equipment according to Figure 2 and check the air tightness of the equipment.
(2) Suck 2 mL of saturated saline into a small plastic syringe (the needle has been removed).
(3) Prepare Cl2 with potassium permanganate and concentrated hydrochloric acid, and connect a 30×200 mm large test tube with Cl2 collected to the device.
(4) The dilute hydrochloric acid reacts with zinc particles in a Kipp generator to prepare H2, and after the purity test is qualified, the H2 outlet conduit is connected with the thin infusion tube at the bottom of the electronic lighter.
(5) Inject the saturated saline in the syringe into the large test tube. ?
(6) Press the ignition handle of the electronic lighter lightly to open the valve for controlling H2 airflow. After a short delay (2-3 seconds) to make H2 fill the capillary steel tube, press the ignition handle completely, and the generated electric spark ignites H2, so that the pale flame generated by H2 burning in Cl2 can be observed. With the combustion, the yellow-green color of the gas in the flask gradually becomes lighter, and the shape of the infusion catheter between the interface of the three-way infusion set and the water stop clip becomes smaller. By turning the "handle" on the lighter to control the airflow, the size of the flame can be adjusted. At the beginning, the flame can be large because of the high concentration of Cl2, and it can be small because of the low concentration of Cl2 in the later stage of the reaction, which is beneficial to the depletion of Cl2 in the flask. When the color of the gas in the big test tube is almost colorless and the flame just goes out, the gas valve can be closed by loosening the lighter handle to stop introducing H2.
(7) Open the water stop clip, and the fountain phenomenon can be observed in the large test tube, and the purple litmus test solution entering the large test tube turns red (it will not fade even if it is left for a long time). This experimental phenomenon shows that HCl generated by H2 burning in Cl2 is soluble in water, and its aqueous solution is acidic.
(8) After the experiment is completed, neutralize the waste liquid in the flask with NaOH solution.