Step 1: Understanding the Concept:
To find the nature of the final solution, we need to compare the milliequivalents (meq) of the acid and the base.
If acid meq \(>\) base meq, the solution is acidic; if base meq \(>\) acid meq, it is basic.
: Key Formula or Approach:
Milliequivalents (meq) \( = \text{Molarity} \times \text{n-factor} \times \text{Volume in mL} \).
The n-factor for HCl is 1 (monoprotic acid).
The n-factor for \( \text{Na}_{2}\text{CO}_{3} \) is 2 (salt of a diprotic acid reacting to form \( \text{CO}_{2} \)).
Step 2: Detailed Explanation:
1. Calculate meq of HCl:
\[ \text{meq}_{\text{HCl}} = 1.0 \text{ M} \times 1 \times 100 \text{ mL} = 100 \text{ meq} \]
2. Calculate meq of \( \text{Na}_{2}\text{CO}_{3} \):
\[ \text{meq}_{\text{base}} = 1.0 \text{ M} \times 2 \times 75 \text{ mL} = 150 \text{ meq} \]
3. Compare the values:
Since \( 150 \text{ meq (base)}>100 \text{ meq (acid)} \), the base is in excess.
4. The remaining excess base (\( \text{Na}_{2}\text{CO}_{3} \)) will make the final solution basic.
Step 3: Final Answer:
The resulting solution is basic.