The reason why the liquid level rises is that the rust of nails consumes oxygen in the test tube, making the pressure in the test tube lower than atmospheric pressure.
Analysis and verification:
(1) Because ferric chloride is soluble in water, the black solid substance at the bottom of the test tube is not ferric chloride.
(2) Because the nail is ferroalloy and contains carbon, the black solid substance at the bottom of the test tube contains carbon.
(3) The experimental steps, phenomena and conclusions are shown in the table.
Experimental steps, experimental phenomena and experimental conclusions Dilute hydrochloric acid (or dilute sulfuric acid)? Is there a bubble (no bubble)? Include (not include)? Knowledge link:
Salt water will accelerate the rust rate of iron.