Look at the following chemical equation.

Question

AgI + Na2S → Ag2S + 2NaI
What is true about this chemical equation?
A. It is balanced because the number of reactants is equal to the number of products.
B. It is unbalanced because the number of reactants is greater than the number of products.
C. It is unbalanced because the reactants contain fewer silver (Ag) atoms than the products.
D. It is balanced because the reactants contain the same number of sulfur (S) atoms as the products.

Answer 1

To determine whether the chemical equation is balanced, we can count the number of each type of atom on both the reactant and product sides.

The equation is: \[ \text{AgI} + \text{Na}_2\text{S} \rightarrow \text{Ag}_2\text{S} + 2\text{NaI} \]

Counting atoms:

Reactants:

• Ag: 1 (from AgI)
• I: 1 (from AgI)
• Na: 2 (from Na2S)
• S: 1 (from Na2S)

Total in reactants:

• Ag: 1
• I: 1
• Na: 2
• S: 1

Products:

• Ag: 2 (from Ag2S)
• S: 1 (from Ag2S)
• Na: 2 (from 2NaI)
• I: 2 (from 2NaI)

Total in products:

• Ag: 2
• S: 1
• Na: 2
• I: 2

Now, compare the totals:

• Silver (Ag): 1 (reactants) vs. 2 (products) → not balanced
• Iodine (I): 1 (reactants) vs. 2 (products) → not balanced
• Sodium (Na): 2 (reactants) vs. 2 (products) → balanced
• Sulfur (S): 1 (reactants) vs. 1 (products) → balanced

Since there are differences in the counts of Ag and I, the equation is not balanced.

Thus, the correct statement about the chemical equation is: C. It is unbalanced because the reactants contain fewer silver (Ag) atoms than the products.