To determine which statement best describes the equation [tex]\( \text{CaCO}_3 + 2 \text{HCl} \rightarrow \text{CaCl}_2 + \text{CO}_2 + \text{H}_2\text{O} \)[/tex], it is crucial to distinguish between reactants and products in the chemical reaction.
### Understanding the Reaction
- Reactants are the substances that are present before the chemical reaction takes place. They are on the left side of the equation.
- Products are the substances that are formed as a result of the chemical reaction. They are on the right side of the equation.
In the given equation:
[tex]\[ \text{CaCO}_3 + 2 \text{HCl} \rightarrow \text{CaCl}_2 + \text{CO}_2 + \text{H}_2\text{O} \][/tex]
- [tex]\( \text{CaCO}_3 \)[/tex] (Calcium carbonate) and [tex]\( \text{HCl} \)[/tex] (Hydrochloric acid) are the reactants because they are on the left side of the equation, meaning they are present before the reaction occurs.
- [tex]\( \text{CaCl}_2 \)[/tex] (Calcium chloride), [tex]\( \text{CO}_2 \)[/tex] (Carbon dioxide), and [tex]\( \text{H}_2\text{O} \)[/tex] (Water) are the products because they are on the right side of the equation, meaning they are formed as a result of the reaction.
### Evaluating the Statements
1. [tex]\( \text{CaCO}_3 \)[/tex] is a reactant; it is present before the reaction occurs.
- This statement is true. [tex]\( \text{CaCO}_3 \)[/tex] is on the left side of the equation and is thus a reactant.
2. [tex]\( \text{CaCl}_2 \)[/tex] is a reactant; it is present before the reaction occurs.
- This statement is false. [tex]\( \text{CaCl}_2 \)[/tex] is on the right side of the equation, showing that it is a product, not a reactant.
3. [tex]\( \text{CO}_2 \)[/tex] is a reactant because it is most likely a gas.
- This statement is false. Although [tex]\( \text{CO}_2 \)[/tex] is likely a gas, it is a product, as it appears on the right side of the equation.
4. [tex]\( \text{H}_2\text{O} \)[/tex] is a reactant because it is most likely a liquid.
- This statement is false. While [tex]\( \text{H}_2\text{O} \)[/tex] is typically a liquid, in this context it is a product, as it is on the right side of the equation.
### Conclusion
The best statement describing the equation [tex]\( \text{CaCO}_3 + 2 \text{HCl} \rightarrow \text{CaCl}_2 + \text{CO}_2 + \text{H}_2\text{O} \)[/tex] is:
"CaCO_3 is a reactant; it is present before the reaction occurs."
This accurately identifies [tex]\( \text{CaCO}_3 \)[/tex] as one of the substances present before the reaction, making it a reactant.
