Chemistry 8 Lesson 7: Practice 2
1. Summary of theory
1.1. Experiment purpose
– Experiments on the diffusion of substances
– Know the safety rules in the laboratory
– Have a spirit of learning, thinking and discovering interesting scientific phenomena
1.2. Some safety rules in the laboratory
– Experiments are only allowed in the presence of teachers in the laboratory.
1.3. Laboratory instruments, chemicals
– Test tube with rubber stopper
– Glass cup, glass wand
– Ammonia solution, distilled water
– Purple litmus, cotton
– Potassium permanganate (purple medicine)
1.4. Experimental steps
a. Experiment 1: Diffusion of Ammonia
2. Experimental results
2.1. Experiment 1: Diffusion of Ammonia
2.2. Experiment 2: The spread of potassium permanganate (permanganate) in water
Describe what was observed in each experiment and explain.
– Phenomenon: After a while, the purple litmus turns blue.
– Explanation: Because the ammonia gas from the cotton has moved along the air molecules in the bottle, to the litmus paper, the litmus paper turns green.
– In cup 1, after stirring, the cup of water is purple.
– In cup 2, only the places with potassium permanganate will be purple, but if you leave it for a long time, the cup of water will be purple.
– In cup 1, it is because when stirring, the water molecules move with the potassium permanganate molecules, making the cup purple.
– In cup 2, because when left alone, the water molecules move slowly, so it takes a long time for the new cup to turn purple.
Through the lesson, you will learn:
- Skills in using some tools and chemicals in the laboratory
- Compare the diffusion capacity of ammonia and potassium permanganate