Question

Which of the following mixing of 1M base and 1M acid leads to the largest increase in temperature?

• A. 30 mL \( \text{CH}_3\text{COOH} \) and 30 mL NaOH
• B. 45 mL \( \text{CH}_3\text{COOH} \) and 25 mL NaOH
• C. 50 mL HCl and 20 mL NaOH
• D. 30 mL HCl and 30 mL NaOH

Hint:

Strong acid and strong base neutralization reactions generate the maximum heat compared to weak acid and base neutralizations.

Answer 1

The Correct Option is C

- The heat generated in an acid-base neutralization reaction is proportional to the amount of acid and base mixed, which is the product of the molarities and volumes.
- The combination that results in the largest heat release will have the highest product of molarities and volumes.
- When comparing the options, the mix of 50 mL of HCl and 20 mL of NaOH will have the highest heat increase since it involves a strong acid and a strong base, leading to the largest amount of heat generated.

Final Answer: Option (3).

Answer 2

Step 1: Understand the process.
When an acid and a base are mixed, they undergo a neutralization reaction: \[ \text{Acid} + \text{Base} \rightarrow \text{Salt} + \text{Water}. \] The reaction releases heat, which causes an increase in temperature. The amount of heat released is determined by the amount of acid and base mixed, and their respective concentrations.

Step 2: Key factors affecting the temperature increase.
The heat released during a neutralization reaction is proportional to the amount of acid and base reacting, which depends on their concentrations and volumes. Since both acid and base are 1M (1 mole per liter), the heat released depends on the number of moles of acid and base that react. This is given by: \[ \text{Heat released} \propto \text{moles of acid} + \text{moles of base}. \] The larger the volume of acid and base, the more moles will react, leading to a greater temperature increase.

Step 3: Compare the options.
The heat released will be the greatest when the volume of acid and base is the highest. Since 1M concentrations are provided, the heat released is directly related to the volume of acid and base used.
- 50 mL HCl (acid) and 20 mL NaOH (base) will provide a higher total number of moles compared to smaller volumes of acid and base.

Final Answer:
\[ \boxed{50 \text{ mL HCl and 20 mL NaOH}}. \]