Question

balancing chemical equations by dividing by mass

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GPT-4o mini
Balancing chemical equations typically involves ensuring that the number of each type of atom is the same on both sides of the equation. The approach of dividing by mass is not a standard method for balancing equations. Instead, balancing is generally done using the coefficients in front of the chemical formulas to indicate the number of moles of each substance.

Here’s an overview of the correct process for balancing a chemical equation:

### Steps to Balance a Chemical Equation:

1. **Write the Unbalanced Equation**: Start with the unbalanced chemical equation. For example:
\[
\text{C}_3\text{H}_8 + \text{O}_2 \rightarrow \text{CO}_2 + \text{H}_2\text{O}
\]

2. **List the Number of Atoms**: Count the number of atoms of each element on both sides of the equation.

3. **Adjust Coefficients**: Begin adding coefficients (whole numbers placed before compounds) to balance one element at a time. It's important to balance the most complex molecule first (the one with the most different types of atoms).

4. **Balance Hydrogen and Oxygen Last**: Hydrogen and oxygen are often found in multiple compounds, so it is usually easiest to balance them last.

5. **Check Your Work**: After adding coefficients, recount the number of each type of atom on both sides to ensure they are equal.

### Example: Balancing Propane Combustion

Let's balance the combustion of propane (\(\text{C}_3\text{H}_8\)):

1. Write the unbalanced equation:
\[
\text{C}_3\text{H}_8 + \text{O}_2 \rightarrow \text{CO}_2 + \text{H}_2\text{O}
\]

2. Count the atoms:
- Left: C = 3, H = 8, O = 2 (from \(\text{O}_2\))
- Right: C from \(\text{CO}_2\), H from \(\text{H}_2\text{O}\)

3. Start with carbon (C):
- Place a coefficient of 3 in front of \(\text{CO}_2\):
\[
\text{C}_3\text{H}_8 + \text{O}_2 \rightarrow 3\text{CO}_2 + \text{H}_2\text{O}
\]

4. Then balance hydrogen (H):
- Place a coefficient of 4 in front of \(\text{H}_2\text{O}\):
\[
\text{C}_3\text{H}_8 + \text{O}_2 \rightarrow 3\text{CO}_2 + 4\text{H}_2\text{O}
\]

5. Finally, balance oxygen (O):
- On the right side, we have \(3 \times 2 + 4 \times 1 = 6 + 4 = 10\) O.
- Thus, we need 5 \(\text{O}_2\) (since \(\frac{10}{2} = 5\)):
\[
\text{C}_3\text{H}_8 + 5\text{O}_2 \rightarrow 3\text{CO}_2 + 4\text{H}_2\text{O}
\]

6. The final balanced equation is:
\[
\text{C}_3\text{H}_8 + 5\text{O}_2 \rightarrow 3\text{CO}_2 + 4\text{H}_2\text{O}
\]

### Summary

Estimating stoichiometry based on mass isn't a key balancing technique — instead, focus on counting atoms and adjusting coefficients. This systematic approach effectively balances chemical equations according to the law of conservation of mass. If you have insights about a specific context in which mass division applies to balancing, please clarify!

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