Ch.5 - Thermochemistry

Brown - Chemistry: The Central Science 15th Edition

Brown15th EditionChemistry: The Central ScienceISBN: 9780137542970Not the one you use?Change textbook

Brown 15th Edition

Ch.5 - Thermochemistry

Problem 49

Chapter 5, Problem 49

b. What are the units of specific heat?

Verified step by step guidance

Understand that specific heat is a property of a substance that indicates how much heat energy is required to raise the temperature of a given mass of the substance by one degree Celsius (or one Kelvin).

Recall the formula for specific heat: \( q = mc\Delta T \), where \( q \) is the heat absorbed or released, \( m \) is the mass, \( c \) is the specific heat, and \( \Delta T \) is the change in temperature.

Identify the units for each component in the formula: \( q \) is typically measured in joules (J), \( m \) in grams (g), and \( \Delta T \) in degrees Celsius (°C) or Kelvin (K).

Rearrange the formula to solve for specific heat \( c \): \( c = \frac{q}{m\Delta T} \).

Determine the units of specific heat by substituting the units of each variable into the rearranged formula: \( c \) has units of \( \frac{J}{g \cdot °C} \) or \( \frac{J}{g \cdot K} \).

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Specific Heat Capacity

Specific heat capacity is the amount of heat required to raise the temperature of one gram of a substance by one degree Celsius (°C) or one Kelvin (K). It is a material property that indicates how much energy is needed to change the temperature of a substance, which varies between different materials.

Units of Measurement

The units of specific heat are typically expressed in joules per gram per degree Celsius (J/g·°C) or joules per kilogram per Kelvin (J/kg·K). These units reflect the energy (in joules) needed to change the temperature of a specific mass of a substance, highlighting the relationship between heat energy, mass, and temperature change.

Heat Transfer

Heat transfer is the process of thermal energy moving from one object or substance to another due to a temperature difference. Understanding specific heat is crucial in heat transfer calculations, as it helps predict how much energy will be absorbed or released by a substance when it undergoes a temperature change.

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Heat Capacity

Related Practice

Textbook Question

Consider the decomposition of liquid benzene, C₆H₆(l), to gaseous acetylene, C₂H₂(g): C₆H₆(l) → 3 C2H₂(g) ΔH = +630 kJ (c) Which is more likely to be thermodynamically favored, the forward reaction or the reverse reaction?

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Textbook Question

Consider the decomposition of liquid benzene, C₆H₆(l), to gaseous acetylene, C₂H₂(g): C₆H₆(l) → 3 C2H₂(g) ΔH = +630 kJ (a) What is the enthalpy change for the reverse reaction?

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Textbook Question

(d) How many kJ of heat are needed to raise the temperature of 10.00 kg of liquid water from 24.6 to 46.2 °C?

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Textbook Question

Consider the decomposition of liquid benzene, C₆H₆(l), to gaseous acetylene, C₂H₂(g): C₆H₆(l) → 3 C2H₂(g) ΔH = +630 kJ (b) What is H for the formation of 1 mol of acetylene?

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Textbook Question

Two solid objects, A and B, are placed in boiling water and allowed to come to the temperature of the water. Each is then lifted out and placed in separate beakers containing 1000 g of water at 10.0 °C. Object A increases the water temperature by 3.50 °C; B increases the water temperature by 2.60 °C. (a) Which object has the larger heat capacity?

(b) Calculate the energy needed for this temperature change.

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