Question

Select the correct answer. A student places a sample of white sodium bicarbonate powder in a test tube and heats it. The student observes that the sodium bicarbonate undergoes a chemical change. After the change, what must be true about the substance in the test tube? A. It is not white. B. It is a liquid. C. It is an element. D. It is not sodium bicarbonate.

Answer 1

Answer is: D. It is not sodium bicarbonate.

Balanced chemical reaction of heating sodium bicarbonate:                    2NaHCO₃ → Na₂CO₃ + CO₂ + H₂O.

This is chemical change (chemical reaction), because new substances are formed (sodium carbonate, carbon(IV) oxide and water), the atoms are rearranged, so there is no sodium bicarbonate (NaHCO₃) in the test tube.