When anhydrous copper sulfate is mixed with water, it will absorb the water and change in appearance, becoming a blue crystalline
Place a lighted splint in a test tube containing the gas. If the gas is hydrogen, there will be a squeaky pop
The glowing splint test is when you place the glowing splint into the unknown gas. In carbon dioxide, the splint goes out completely. In oxygen, the splint reignites.
If carbon dioxide is bubbled through limewater, the limewater turns milky or cloudy white.