This is an acid-base reaction (neutralization): KHCO3 is a base, H2SO4 is an acid.
This is a gas evolution reaction, CO2 is the formed gas.
Reactants:
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KHCO3 – Potassium hydrogen carbonate
Other names: Potassium bicarbonate, Potassium acid carbonate, KHCO3
Appearance: White crystals
H2SO4 – Sulfuric acid
Other names: Oil of vitriol, Sulfuric acid, concentrated (> 51% and , H2SO4
Appearance: Clear, colorless liquid ; Odourless colourless oily hygroscopic liquid ; Colorless to dark-brown, oily, odorless liquid. [Note: Pure compound is a solid below 51°F. Often used in an aqueous solution.]
Appearance: White solid ; Colourless-to-white crystals
CO2
Names: Carbon dioxide, {{plainlist|, CO2
Appearance: Colorless gas ; Odourless colourless compressed liquefied gas ; Colorless, odorless gas. [Note: Shipped as a liquefied compressed gas. Solid form is utilized as dry ice.]
H2O – Water, oxidane
Other names: Water (H2O), Hydrogen hydroxide (HH or HOH), Hydrogen oxide
Appearance: White crystalline solid, almost colorless liquid with a hint of blue, colorless gas