Sugar Char Challenge

Why it matters

Pour concentrated sulphuric acid onto sugar and watch it turn into a towering black snake of carbon. The acid doesn't burn it; it strips the water right out of the molecules.

The idea in plain words

Analyze the equation: C₁₂H₂₂O₁₁ → 12C + 11H₂O. Notice how the H and O atoms leave as water, leaving only C.

Predict first

Why does the white sugar turn into black, spongy carbon?

Concentrated sulphuric acid is a powerful dehydrating agent. It pulls hydrogen and oxygen atoms out of the sugar in the ratio of water (2:1), leaving behind pure carbon.

• The acid burns the sugar with intense heat
• The acid pulls hydrogen and oxygen out of the sugar as water (in a 2:1 ratio), leaving carbon — correct
• The acid reacts with carbon to form a black salt
• The sugar dissolves and changes color due to pH

What you do

Add the acid to the sugar. Observe the charring and the expansion of the black mass.

Check yourself

What is the specific role of concentrated H₂SO₄ in this reaction?

It removes water (H and O) from the compound, which defines a dehydrating agent.

Which observation confirms the formation of water during the charring process?

The reaction is exothermic and produces water vapor, often seen as steam or fumes rising from the black carbon mass.

If you passed the evolved gas through white anhydrous copper sulphate, what would happen?

The reaction produces H₂O. White anhydrous CuSO₄ turns blue when it hydrates to form CuSO₄·5H₂O, confirming the presence of water.

• Catalyst
• Dehydrating agent — correct
• Oxidizing agent
• Reducing agent
• The mixture turns black
• Steam/fumes are evolved — correct
• The beaker becomes cold
• The sugar dissolves completely
• It would turn blue — correct
• It would remain white
• It would turn black
• It would dissolve