Textbook Question
When a 5.10-g sample of solid sodium hydroxide dissolves in 100.0 g of water in a coffee-cup calorimeter (Figure 5.18), the temperature rises from 20.5 to 33.2 °C. a. Calculate the quantity of heat (in kJ) released in the reaction.
Ch.5 - Thermochemistry
Chapter 5, Problem 57a
A 2.200-g sample of quinone (C6H4O2) is burned in a bomb calorimeter whose total heat capacity is 7.854 kJ/°C. The temperature of the calorimeter increases from 23.44 to 30.57 °C. (a) What is the heat of combustion per gram of quinone?
Verified step by step guidance1
Calculate the temperature change (\( \Delta T \)) of the calorimeter by subtracting the initial temperature from the final temperature: \( \Delta T = 30.57 \, ^\circ\text{C} - 23.44 \, ^\circ\text{C} \).
Use the formula for heat absorbed by the calorimeter: \( q = C_{\text{cal}} \times \Delta T \), where \( C_{\text{cal}} \) is the heat capacity of the calorimeter (7.854 kJ/°C).
Substitute the values into the formula to find the total heat absorbed by the calorimeter: \( q = 7.854 \, \text{kJ/°C} \times \Delta T \).
Determine the heat of combustion per gram of quinone by dividing the total heat absorbed by the mass of the quinone sample: \( \text{Heat of combustion per gram} = \frac{q}{\text{mass of quinone}} \).
Substitute the mass of the quinone sample (2.200 g) into the equation to find the heat of combustion per gram.
Verified video answer for a similar problem:
This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
4mWas this helpful?
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Heat Capacity
Heat capacity is the amount of heat energy required to change the temperature of a substance by one degree Celsius. In calorimetry, the heat capacity of the calorimeter is crucial for determining the total heat absorbed during a reaction. It allows us to calculate the heat released by the combustion of a sample by multiplying the heat capacity by the change in temperature.
Recommended video:
Guided course
02:19
Heat Capacity
Calorimetry
Calorimetry is the science of measuring the heat of chemical reactions or physical changes. In a bomb calorimeter, the heat released from a combustion reaction is measured by observing the temperature change in the calorimeter. This technique is essential for determining the energy content of fuels and other substances, such as quinone in this case.
Recommended video:
Guided course
00:50Constant-Volume Calorimetry
Heat of Combustion
The heat of combustion is the amount of energy released when a substance is completely burned in oxygen. It is typically expressed in joules or kilojoules per gram. To find the heat of combustion per gram of quinone, the total heat released during the combustion process is divided by the mass of the sample, providing a measure of its energy content.
Recommended video:
Guided course
02:24Combustion Apparatus
Related Practice
Textbook Question
When a 5.10-g sample of solid sodium hydroxide dissolves in 100.0 g of water in a coffee-cup calorimeter (Figure 5.18), the temperature rises from 20.5 to 33.2 °C. b. Using your result from part (a), calculate ΔH (in kJ/mol NaOH) for the solution process. Assume that the specific heat of the solution is the same as that of pure water.
Textbook Question
(b) Is this process endothermic or exothermic?
1
views
Textbook Question
A 2.200-g sample of quinone (C6H4O2) is burned in a bomb calorimeter whose total heat capacity is 7.854 kJ/°C. The temperature of the calorimeter increases from 23.44 to 30.57 °C. b. What is the heat of combustion per mole of quinone?
Textbook Question
A 1.800-g sample of phenol (C6H5OH) was burned in a bomb calorimeter whose total heat capacity is 11.66 kJ/°C. The temperature of the calorimeter plus contents increased from 21.36 to 26.37 °C. a. Write a balanced chemical equation for the bomb calorimeter reaction.
Textbook Question
A 1.800-g sample of phenol (C6H5OH) was burned in a bomb calorimeter whose total heat capacity is 11.66 kJ/°C. The temperature of the calorimeter plus contents increased from 21.36 to 26.37 °C. b. What is the heat of combustion per gram of phenol?