The following chemical equation shows the incomplete formula for burning methanol. The question mark represents the unknown number of oxygen (O2) molecules. How many molecules of O2 are needed to balance this chemical equation?
2CH₃OH + ?O₂ > 2CO₂ + 4H₂O
A. 1
B. 3
C. 5
D. 6
is it 6?????????/
is it 3?
yup ... again
atoms, yes ... molecules, no
To balance a chemical equation, you need to ensure that the number of atoms of each element is equal on both sides of the equation. In this case, you want to balance the number of oxygen (O) atoms.
Let's start by counting the number of oxygen (O) atoms present on each side of the equation:
On the left side:
- 2 CH₃OH molecules contain 2 oxygen atoms
- ?O₂ has an unknown number of oxygen atoms
On the right side:
- 2 CO₂ molecules contain 4 oxygen atoms
- 4 H₂O molecules contain 4 oxygen atoms
Since there are 2 oxygen atoms on the left side, and a total of 8 oxygen atoms on the right side, we need to balance the equation by adding oxygen (O₂) to the left side.
To get the number of O₂ molecules needed, we can compare the number of oxygen atoms on each side. In this case, we have 8 oxygen atoms on the right side and 2 oxygen atoms on the left side.
To balance the equation, we need 6 more oxygen atoms on the left side. Since each molecule of O₂ contains 2 oxygen atoms, we need 6/2 = 3 O₂ molecules.
Therefore, the correct answer is B. 3.