Question

Consider the chemical equation for the combustion of sugar. _C6H12O6(s) _O2(g) Right arrow. _CO2(g) _H2O(l) Which sequence of coefficients should be placed in the blanks to balance this equation? 1, 6, 6, 6 6, 1, 6, 1 3, 3, 3, 6 1, 3, 3, 6

Answer 1

C₆H₁₂O₆ + O₂   ⇄   CO₂ + H₂O

There are 6 carbons on the left side, so you need at least 6 molecules of CO₂ on the right.

You also have 12 hydrogens on the left, so you need at least 6 molecules of H₂O on the right.

The reaction so far is then

C₆H₁₂O₆ + O₂   ⇄   6 CO₂ + 6 H₂O

Now, on the left, you have a total of 6 + 2 = 8 oxygens, while on the right, you have 12 + 6 = 18 oxygens. To make up the difference, you need 6 molecules of oxygen:

C₆H₁₂O₆ + 6 O₂   ⇄   6 CO₂ + 6 H₂O

so the sequence is 1, 6, 6, 6.