Answer:
Which would cause only a chemical change in a sugar cube is heating the sugar cube with acid.
Explanation:
The complete question is:
Jolene wants to experiment with sugar cubes. Which of the following would cause only a chemical change with a sugar cube
- Burning the sugar cube with a matchstick
.
- Crushing the sugar cube and dissolving it in water
.
- Heating the sugar cube with acid.
The addition of acid to sugar (sucrose) is a known reaction that produces the chemical change of this carbohydrate into carbon, by a process of dehydration.
In the reaction of dehydration of sucrose with sulphuric acid - which is exothermic - the acid extracts water from the sugar molecule, producing gases, such as CO₂ and SO₂, which consumes the acid and converts the sucrose into carbon. The chemical reaction is:
C₁₂H₂₂O₁₁ + H₂SO₄ + 1/2 O₂ ----------→ 11C + CO₂ + 12H₂O + SO₂
Sucrose + Sulfuric Ac. + Oxygen → Carbon + Carbon dioxide + water + sulfur dioxide.
This reaction involves only a chemical change of the sucrose, when converted into carbon.
