Which equation is the balanced equation for Ca + O₂ → CaO?
A. 4Ca+20₂ → 2CaO
B. 2Ca+20₂ → 2CaO
C. Ca+O,→CaO
D. 2Ca+0₂ → 2CaO
The Correct Answer and Explanation is:
The correct balanced equation for the reaction between calcium (Ca) and oxygen (O₂) to form calcium oxide (CaO) is:
B. 2Ca + O₂ → 2CaO
Explanation:
In order to balance a chemical equation, the number of atoms of each element must be the same on both sides of the equation. The unbalanced equation provided is:
Ca + O₂ → CaO
Here’s how we balance the equation step by step:
- Balance the calcium (Ca) atoms: On the left side, we have 1 atom of calcium, while on the right side, we have only 1 atom of calcium in CaO. Initially, this seems balanced for calcium, but we need to check the oxygen atoms.
- Balance the oxygen (O) atoms: On the left side, O₂ has 2 oxygen atoms, and on the right side, each CaO molecule contains 1 oxygen atom. Therefore, in order to have 2 oxygen atoms on the right side, we need to have 2 molecules of CaO. This gives us: Ca + O₂ → 2CaO
- Balance the calcium atoms again: Now, we have 2 oxygen atoms on both sides (because 2 molecules of CaO are on the right), but we need 2 atoms of calcium to match the 2 CaO molecules. So, we add 2 calcium atoms on the left side: 2Ca + O₂ → 2CaO
This is the balanced equation. Notice that the number of calcium atoms is the same on both sides (2 atoms), and the number of oxygen atoms is also balanced (2 atoms on each side).
Why Other Options Are Incorrect:
- A. 4Ca + 2O₂ → 2CaO: This equation suggests there are 4 calcium atoms on the left, but only 2 on the right. This is incorrect because the number of calcium atoms does not match.
- C. Ca + O₂ → CaO: This is the unbalanced equation, which doesn’t respect the atom count for oxygen and calcium.
- D. 2Ca + O₂ → 2CaO: This option is correct, but it is presented differently as option B, which makes it redundant.
Thus, the correct balanced equation is B. 2Ca + O₂ → 2CaO.