In order to determine the base in the given reaction, we need to identify the substance that accepts protons (H\(^+\) ions).
Consider the balanced chemical equation:
[tex]\[
H_2SO_4(aq) + Ca(OH)_2(aq) \rightarrow CaSO_4(aq) + 2H_2O(l)
\][/tex]
Let's break down the substances involved:
1. \( H_2SO_4 \):
- Sulfuric acid, \( H_2SO_4 \), is well known as a strong acid. Acids are proton donors, meaning they release H\(^+\) ions in a reaction.
2. \( Ca(OH)_2 \):
- Calcium hydroxide, \( Ca(OH)_2 \), is a base. Bases accept protons by providing hydroxide ions (OH\(^-\)) which then combine with H\(^+\) ions to form water (H\(_2\)O).
3. \( CaSO_4 \):
- Calcium sulfate, \( CaSO_4 \), is a salt resulting from the neutralization reaction between the acid and the base. It is neither an acid nor a base in this context.
4. \( 2 H_2O \):
- Water, \( 2 H_2O \), is a product formed when hydroxide ions (OH\(^-\)) from the base react with protons (H\(^+\)) from the acid.
Given the definitions:
- \( H_2SO_4 \) is the acid because it donates protons.
- \( Ca(OH)_2 \) is the base because it accepts protons.
Thus, the substance that acts as the base in the reaction is:
[tex]\[ Ca(OH)_2(aq) \][/tex]
Therefore, the base in the reaction is indeed:
[tex]\[ \boxed{Ca(OH)_2(aq)} \][/tex]
