How to Calculate Energy Absorbed or Released: A Comprehensive Guide

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How to Calculate Energy Absorbed or Released

Energy absorption and release are fundamental concepts in the field of physics and chemistry. Understanding how to calculate the amount of energy absorbed or released in a system is crucial for various applications, ranging from thermodynamics and calorimetry to chemical reactions and heat transfer. In this blog post, we will explore the process of calculating energy absorption and release, discuss their importance, and delve into advanced concepts in energy calculations. Let’s get started!

Understanding the Concept of Energy Absorption and Release

Energy absorption refers to the process of taking in energy from the surroundings, while energy release involves the opposite – releasing energy into the surroundings. Both processes are governed by the fundamental laws of thermodynamics, which describe how energy can be transferred and transformed.

Energy can exist in different forms, such as kinetic energy (associated with motion) and potential energy (associated with position or configuration). When a system absorbs or releases energy, there is a change in the overall energy level of the system.

Importance of Calculating Energy Absorption and Release

Calculating energy absorption and release is essential for several reasons. Firstly, it allows us to understand and predict the behavior of physical and chemical systems. By quantifying the amount of energy involved, we can determine the stability, reactivity, and overall energetics of a system.

Secondly, energy calculations are crucial for various practical applications. For example, in the field of thermodynamics, knowing the amount of energy absorbed or released during a process helps us analyze and design efficient heat engines, refrigeration systems, and power plants.

III. The Process of Calculating Energy Absorption

A. Identifying the Variables for Energy Absorption Calculation

To calculate the energy absorbed by a system, we need to consider several variables:

  1. Initial Energy (Einitial): The energy of the system before any energy absorption takes place.
  2. Final Energy (Efinal): The energy of the system after the absorption process.
  3. Energy Change (ΔE): The difference between the initial and final energies, given by the equation:

Delta E = E_{text{final}} - E_{text{initial}}

B. Step-by-Step Guide to Calculate Energy Absorption

To calculate the energy absorbed by a system, follow these steps:

  1. Determine the initial energy (Einitial) of the system.
  2. Determine the final energy (Efinal) of the system.
  3. Use the equation Delta E = E_{text{final}} - E_{text{initial}} to find the energy change.
  4. The energy absorbed (Eabsorbed) is equal to the absolute value of the energy change (|ΔE|).

C. Worked Out Examples of Energy Absorption Calculation

Example 1:
A ball is dropped from a height of 10 meters. Determine the energy absorbed by the ball.

  1. Initial energy (Einitial) = Potential energy = mgh, where m is the mass of the ball, g is the acceleration due to gravity, and h is the height.
  2. Final energy (Efinal) = Kinetic energy = 0, as the ball comes to rest at the ground.
  3. Energy change (ΔE) = Efinal – Einitial = 0 – mgh = -mgh.
  4. Energy absorbed (Eabsorbed) = |ΔE| = mgh.

Example 2:
A chemical reaction releases 1000 Joules of energy. Determine the energy absorbed.

  1. Initial energy (Einitial) = 0, as there is no initial energy.
  2. Final energy (Efinal) = -1000 Joules, as the reaction releases energy.
  3. Energy change (ΔE) = Efinal – Einitial = -1000 – 0 = -1000 Joules.
  4. Energy absorbed (Eabsorbed) = |ΔE| = 1000 Joules.

IV. The Process of Calculating Energy Release

A. Identifying the Variables for Energy Release Calculation

To calculate the energy released by a system, we consider similar variables as in energy absorption:

  1. Initial Energy (Einitial): The energy of the system before any energy release takes place.
  2. Final Energy (Efinal): The energy of the system after the release process.
  3. Energy Change (ΔE): The difference between the initial and final energies.

B. Step-by-Step Guide to Calculate Energy Release

To calculate the energy released by a system, follow these steps:

  1. Determine the initial energy (Einitial) of the system.
  2. Determine the final energy (Efinal) of the system.
  3. Use the equation Delta E = E_{text{final}} - E_{text{initial}} to find the energy change.
  4. The energy released (Ereleased) is equal to the absolute value of the energy change (|ΔE|).

C. Worked Out Examples of Energy Release Calculation

Example 1:
A battery releases 50 Joules of electrical energy. Determine the energy released.

  1. Initial energy (Einitial) = 0, as there is no initial energy.
  2. Final energy (Efinal) = -50 Joules, as the battery releases energy.
  3. Energy change (ΔE) = Efinal – Einitial = -50 – 0 = -50 Joules.
  4. Energy released (Ereleased) = |ΔE| = 50 Joules.

Example 2:
A substance undergoes combustion, releasing 5000 Joules of heat. Determine the energy released.

  1. Initial energy (Einitial) = 0, as there is no initial energy.
  2. Final energy (Efinal) = -5000 Joules, as the combustion releases heat.
  3. Energy change (ΔE) = Efinal – Einitial = -5000 – 0 = -5000 Joules.
  4. Energy released (Ereleased) = |ΔE| = 5000 Joules.

V. Advanced Concepts in Calculating Energy Absorbed or Released

A. How to Calculate the Amount of Energy Absorbed or Released by a Reaction

In chemical reactions, the amount of energy absorbed or released can be quantified using the concept of enthalpy change (∆H). The enthalpy change is defined as the difference between the enthalpy of the products (Hproducts) and the enthalpy of the reactants (Hreactants). For an exothermic reaction (energy releasing), ∆H will be negative, while for an endothermic reaction (energy absorbing), ∆H will be positive.

B. How to Calculate How Much Heat Will Be Released or Absorbed

The amount of heat (Q) released or absorbed during a process can be determined using the equation:

Q = m cdot C cdot Delta T

where Q is the heat, m is the mass of the substance, C is the specific heat capacity of the substance, and ΔT is the change in temperature.

C. Worked Out Examples of Advanced Energy Calculations

Example 1:
A sample of water with a mass of 200 grams is heated from 20°C to 80°C. Calculate the amount of heat absorbed.

  1. Mass (m) = 200 grams = 0.2 kg.
  2. Specific heat capacity of water (C) = 4.18 J/g°C.
  3. Change in temperature (ΔT) = 80°C – 20°C = 60°C.
  4. Heat absorbed (Q) = m * C * ΔT = 0.2 kg * 4.18 J/g°C * 60°C = 501.6 Joules.

Example 2:
A chemical reaction releases 150 kJ of energy. Determine the enthalpy change (∆H) for the reaction.

  1. Enthalpy change (∆H) = -150 kJ (negative, as energy is released).
  2. The enthalpy change (∆H) represents the energy released during the reaction.

Calculating the energy absorbed or released in a system is crucial for understanding the behavior of physical and chemical processes. By properly identifying the variables and following the step-by-step guide, we can accurately determine the amount of energy involved. Additionally, advanced concepts such as enthalpy change and heat calculations allow for more precise energy analysis. Remember to apply the appropriate formulas and equations to solve specific energy calculation problems. With a solid understanding of energy absorption and release, you will be better equipped to comprehend and analyze various scientific phenomena.

Numerical Problems on How to Calculate Energy Absorbed or Released

Problem 1:

How to calculate energy absorbed or released
Image by Giorgiogp2 – Wikimedia Commons, Wikimedia Commons, Licensed under CC BY-SA 3.0.
energy absorbed or released 2

A chemical reaction releases 450 kJ of energy when 2 moles of reactant are consumed. How much energy will be absorbed or released when 5 moles of reactant are consumed?

Solution:

Given: Energy released = 450 kJ

Number of moles of reactant = 2

Let’s assume x kJ of energy will be absorbed or released when 5 moles of reactant are consumed.

According to the given information, energy is directly proportional to the number of moles of reactant.

Hence, we can set up the following proportion:

frac{450}{2} = frac{x}{5}

Cross-multiplying, we get:

2x = 5 times 450

Simplifying, we find:

x = frac{5 times 450}{2}

Therefore, when 5 moles of reactant are consumed, the energy absorbed or released will be 1125 kJ.

Problem 2:

energy absorbed or released 1

A battery with a potential difference of 12 volts can supply a current of 1.5 amperes. How much energy is absorbed or released in 2 hours?

Solution:

Given: Potential difference (V) = 12 volts

Current (I) = 1.5 amperes

Time (t) = 2 hours

Energy (E) can be calculated using the formula:

E = V times I times t

Substituting the given values, we find:

E = 12 times 1.5 times 2

Simplifying, we get:

E = 36 joules

Therefore, the energy absorbed or released in 2 hours is 36 joules.

Problem 3:

energy absorbed or released 3

A car with a mass of 1000 kg accelerates from rest to a velocity of 25 m/s. If the work done on the car is 50000 J, what is the energy absorbed or released during this process?

Solution:

Given: Mass (m) = 1000 kg

Initial velocity (v_i) = 0 m/s

Final velocity (v_f) = 25 m/s

Work done (W) = 50000 J

The change in kinetic energy $Delta KE$ can be calculated using the formula:

Delta KE = frac{1}{2} m (v_f^2 - v_i^2)

Substituting the given values, we find:

Delta KE = frac{1}{2} times 1000 times (25^2 - 0^2)

Simplifying, we get:

Delta KE = frac{1}{2} times 1000 times 625

Delta KE = 312500 J

Since work done W) is equal to the change in kinetic energy ($Delta KE$, we have:

W = Delta KE

50000 = 312500

Therefore, the energy absorbed or released during this process is 312500 J.

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