Balance Ca + H₂O → Ca(OH)₂ + H₂
Ca(s) + 2 H₂O(l) → Ca(OH)₂(aq) + H₂(g)
Balance an equation
Ca(s)+2H₂O(l)→Ca(OH)₂(aq)+H₂(g)
Balanced
Atoms on each side
| Atom | As writtenleft : right | Balancedleft : right |
|---|---|---|
| Ca | 1:1 | 1:1 |
| H | 2:4 | 4:4 |
| O | 1:2 | 2:2 |
Check atoms
How to balance it, step by step
- Count the atoms of each element on both sides, as written.
- Start with the biggest formula, Ca(OH)₂: put 1 in front of it.
- Ca: 1 on the right. Put 1 in front of Ca.
- O: 2 on the right. Put 2 in front of H₂O.
- H: 4 on the left, 2 already on the right. Put 1 in front of H₂ (1 × 2 = 2).
- Check: Ca 1 = 1, H 4 = 4, O 2 = 2. Balanced.
What happens
It is a displacement reaction: a more reactive element pushes a less reactive one out of its compound. Calcium reacts less violently with water. The bubbles of hydrogen stick to the metal, so calcium starts floating.
Calcium and water: quick answers
What is the balanced equation for calcium and water?
Ca(s) + 2 H₂O(l) → Ca(OH)₂(aq) + H₂(g). The coefficients are 1, 2, 1 and 1. Each side then has 1 Ca, 4 H and 2 O.
What type of reaction is calcium and water?
It is a displacement reaction: a more reactive element pushes a less reactive one out of its compound. Calcium reacts less violently with water. The bubbles of hydrogen stick to the metal, so calcium starts floating.
How do you balance Ca + H₂O → Ca(OH)₂ + H₂?
Start with the biggest formula, Ca(OH)₂: put 1 in front of it. Ca: 1 on the right. Put 1 in front of Ca. O: 2 on the right. Put 2 in front of H₂O. H: 4 on the left, 2 already on the right. Put 1 in front of H₂ (1 × 2 = 2). Never change a subscript, because that would change the substance.