Xiaofang bought a bottle of vitamin C effervescent tablets. The picture below shows part of the contents on the label of vitamin C effervescent tablets: please use the small square according to the instructions. Carbon dioxide? ;

There are crystals of sodium bicarbonate and tartaric acid in vitamin C effervescent tablets, and there will be CO2； when they react.

Put vitamin C effervescent tablets into a glass of water, and quickly cover the glass with clear lime water;

There is a white film on the lime water;

The gas is carbon dioxide;

① Sodium bicarbonate and tartaric acid crystals in vitamin C effervescent tablets react when dissolved in water;

② Vitamin C effervescent tablets are easily lost at high temperature.