Science Bell Ringer for Grades 9–12: Balancing the equation for burning methane
A free science bell ringer for grades 9–12. Put the prompt on the board as students walk in, give them three to five minutes, then go over it together. The answer and teacher notes are in the box below the prompt.
The prompt
Natural gas is mostly methane (CH4). When it burns completely, it reacts with oxygen to make carbon dioxide and water. Balance the equation, then prove it is balanced by counting atoms on each side.
__ CH4 + __ O2 → __ CO2 + __ H2O
Answer and teacher notes
CH4 + 2 O2 → CO2 + 2 H2O
Atom count: carbon 1 = 1. Hydrogen 4 = 2 × 2 = 4. Oxygen 2 × 2 = 4 on the left; 2 (in CO2) + 2 × 1 (in water) = 4 on the right. Tip: balance C and H first, then O last, since oxygen shows up in both products. Students who change subscripts (writing H4O) have changed the substance, not balanced it.
Source: U.S. Energy Information Administration: Natural Gas Explained
Free to use. Copy, print, project or adapt any of these for your students. If you share them online, please credit Daily Bell Ringers with a link. Not for resale. License: CC BY-NC 4.0.
Browse the full Bell Ringer Library by subject and grade.