When 40.0 mL of 1.00 M H₂SO₄ is added to 80.0 mL of 1.00 M NaOH at 20.0°C in a coffee cup calorimeter, the temperature of the aqueous solution increases to 29.0°C. If the mass of the solution is 120.0 g and the specific heat of the calorimeter and solution is 4.184 J/g·°C, how much heat is given off in the reaction? (Ignore the mass of the calorimeter in the calculation.)

Use: [tex]\( q = m C_p \Delta T \)[/tex]

A. 4.62 kJ
B. 10.0 kJ
C. 14.7 kJ
D. 38.5 kJ



Answer :

Sure, let's go through the detailed solution to determine the heat given off in the reaction using the data provided:

1. Given Values:
- Volume of [tex]\( H_2SO_4 \)[/tex]: [tex]\( 40.0 \, \text{mL} \)[/tex]
- Concentration of [tex]\( H_2SO_4 \)[/tex]: [tex]\( 1.00 \, \text{M} \)[/tex]
- Volume of [tex]\( NaOH \)[/tex]: [tex]\( 80.0 \, \text{mL} \)[/tex]
- Concentration of [tex]\( NaOH \)[/tex]: [tex]\( 1.00 \, \text{M} \)[/tex]
- Initial Temperature: [tex]\( 20.00 \, ^\circ\text{C} \)[/tex]
- Final Temperature: [tex]\( 29.20 \, ^\circ\text{C} \)[/tex]
- Mass of the solution: [tex]\( 120.00 \, \text{g} \)[/tex]
- Specific Heat Capacity ([tex]\( C_p \)[/tex]): [tex]\( 4.184 \, \text{J/g} \cdot ^\circ\text{C} \)[/tex]

2. Calculate the Change in Temperature ([tex]\( \Delta T \)[/tex]):
[tex]\[ \Delta T = \text{Final Temperature} - \text{Initial Temperature} \][/tex]
[tex]\[ \Delta T = 29.20 \, ^\circ\text{C} - 20.00 \, ^\circ\text{C} \][/tex]
[tex]\[ \Delta T = 9.20 \, ^\circ\text{C} \][/tex]

3. Calculate the Heat Given Off in the Reaction (q):
We use the formula [tex]\( q = m \cdot C_p \cdot \Delta T \)[/tex]
[tex]\[ q = 120.00 \, \text{g} \cdot 4.184 \, \text{J/g} \cdot ^\circ\text{C} \cdot 9.20 \, ^\circ\text{C} \][/tex]

4. Calculate q in Joules:
[tex]\[ q = 120.00 \, \text{g} \cdot 4.184 \, \text{J/g} \cdot ^\circ\text{C} \cdot 9.20 \, ^\circ\text{C} \][/tex]
[tex]\[ q = 4619.136 \, \text{J} \][/tex]

5. Convert the Heat from Joules to Kilojoules (kJ):
[tex]\[ \text{Heat given off (in kJ)} = \frac{4619.136 \, \text{J}}{1000} \][/tex]
[tex]\[ \text{Heat given off} = 4.619136 \, \text{kJ} \][/tex]

6. Final Answer:
The heat given off in the reaction is approximately [tex]\( 4.62 \, \text{kJ} \)[/tex].

Hence, the correct choice from the given options would be:

[tex]\[ 4.62 \, \text{kJ} \][/tex]

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