Consider the following chemical reaction: aFe 2O 3(s) + bCO(g) → cFe (s) + dCO 2
1, 3, 2, 3
Balancing a chemical equation ensures that the law of conservation of mass is obeyed. This means the number of atoms of each element must be the same on both the reactant side and the product side of the equation. We are given the unbalanced equation:
\(\text{aFe}_2\text{O}_3\text{(s)} + \text{bCO(g)} \rightarrow \text{cFe (s)} + \text{dCO}_2\text{(g)}\)
Here, a, b, c, and d are the stoichiometric coefficients we need to find to balance the equation.
Let's count the number of atoms of each element on both sides of the equation:
To balance the equation, the number of atoms of each element must be equal on both sides:
We have a system of equations. Let's use the simplest relationship first, which is \(b = d\).
Now substitute \(d\) with \(b\) in the oxygen equation:
\(3a + b = 2(b)\)
\(3a + b = 2b\)
Subtract \(b\) from both sides:
\(3a = 2b - b\)
\(3a = b\)
So, we have the relationships: \(b = 3a\) and \(c = 2a\), and \(d = b\). Since \(b=3a\), we also have \(d=3a\).
To find the smallest whole number coefficients, we can choose a simple value for one variable. Let's assume \(a=1\).
So, the coefficients are \(a=1\), \(b=3\), \(c=2\), and \(d=3\).
Let's plug these values back into the equation:
\(1\text{Fe}_2\text{O}_3\text{(s)} + 3\text{CO(g)} \rightarrow 2\text{Fe (s)} + 3\text{CO}_2\text{(g)}\)
Let's check the atom counts:
| Element | Atoms on Reactant Side | Atoms on Product Side | Balanced? |
|---|---|---|---|
| Fe | \(1 \times 2 = 2\) | \(2 \times 1 = 2\) | Yes |
| O | \((1 \times 3) + (3 \times 1) = 3 + 3 = 6\) | \(3 \times 2 = 6\) | Yes |
| C | \(3 \times 1 = 3\) | \(3 \times 1 = 3\) | Yes |
All elements are balanced. The coefficients a, b, c, and d are 1, 3, 2, and 3 respectively.
The values for a, b, c, and d are 1, 3, 2, and 3.
| Concept | Explanation |
|---|---|
| Law of Conservation of Mass | States that mass in an isolated system is neither created nor destroyed by chemical reactions or physical transformations. In chemical equations, this means the total mass of reactants equals the total mass of products, which translates to having the same number of each type of atom on both sides. |
| Stoichiometric Coefficients | The numbers placed in front of the chemical formulas in a balanced chemical equation. They represent the relative number of molecules or moles of each reactant and product involved in the reaction. |
| Subscripts vs. Coefficients | Subscripts in a chemical formula (like the '2' in \(\text{Fe}_2\)) indicate the number of atoms of an element in a molecule. Coefficients (like the 'a' in \(\text{aFe}_2\text{O}_3\)) are placed in front of the formula and can be changed to balance the equation. Changing a subscript changes the substance itself. |
The reaction between iron(III) oxide (\(\text{Fe}_2\text{O}_3\)) and carbon monoxide (\(\text{CO}\)) is a common example of a redox (reduction-oxidation) reaction, specifically a reduction reaction used in the production of iron from its ore in a blast furnace. \(\text{Fe}_2\text{O}_3\) is reduced to Fe, and \(\text{CO}\) is oxidized to \(\text{CO}_2\). Understanding how to balance these chemical equations is fundamental to calculating quantities of reactants and products in chemistry, a topic known as stoichiometry.
The state symbols (s) for solid and (g) for gas indicate the physical state of the substances under the reaction conditions. Including these symbols makes the chemical equation more informative.
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List-I (Compound/Molecule) | List-II (Shape of Molecule) |
A. CH 3F | 1. Trigonal planar |
B. HCHO | 2. Tetrahedral |
C. HCN | 3. Trigonal pyramidal |
D. NH 3 | 4. Linear |
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