Balanced equation — Science definition
Defined in 2 courses:
- A chemical equation where the number of each type of atom is the same on both sides. (Physical Science: Matter, Forces & Energy)
- An equation with the same number of each kind of atom on both sides, so mass is conserved. (Physical Science: Chemistry)
Where it is taught
- Balancing Chemical Equations — Chemistry, Physical Science: Matter, Forces & Energy, Grade 8
- Balancing Chemical Equations — Reactions, Moles & Composition, Physical Science: Chemistry, Grade 11
In use
That patient back-and-forth is worth it, because a balanced equation is more than just tidy — it's quantitative.
Balancing Chemical Equations
An equation with the same count of each element on both sides is called a balanced equation, and an unbalanced one literally describes an impossible reaction, like a bank statement where money vanishes into thin air.
Balancing Chemical Equations
Questions using balanced equation
Problem 1
- 2
- 4
- 6
- 8
Answer and explanation
4
2 molecules of H₂ each have 2 hydrogen atoms: 2 × 2 = 4 hydrogen atoms.
Problem 2
Answer and explanation
It establishes matching element counts for the stated reaction model. It does not establish that the reaction occurs under any chosen conditions or runs to completion.
It establishes matching element counts for the stated reaction model. It does not establish that the reaction occurs under any chosen conditions or runs to completion.
Response criteria
- Use the supplied conditions and relevant evidence.
- Explain the scientific mechanism or calculation.
- State a meaningful limitation or testable next step.
Problem 3
Answer and explanation
6 atoms
Left: 3H₂ = 3 × 2 = 6 H. Right: 2NH₃ = 2 × 3 = 6 H. They match.
Problem 4
Answer and explanation
2 atoms
O₂ contains 2 oxygen atoms, matching the 2 oxygen atoms in 2H₂O on the product side.
Taught alongside
- chemical equation
- coefficient
- subscript
- model
- evidence
- system boundary
- assumption
- law of conservation of mass