What Is Entropy and How to Calculate It

What Is Entropy and How to Calculate It Entropy is defined  as  the quantitative measure of disorder or randomness in a system. The concept comes out of thermodynamics, which deals with the transfer of heat energy within a system. Instead of talking about some form of absolute entropy, physicists generally discuss the change in entropy that takes place in a specific thermodynamic process. Key Takeaways: Calculating Entropy Entropy is a measure of probability and the molecular disorder of a macroscopic system.If each configuration is equally probable, then the entropy is the natural logarithm of the number of configurations, multiplied by Boltzmanns constant: S kB  ln WFor entropy to decrease, you must transfer energy from somewhere outside the system. How to Calculate Entropy In an isothermal process, the change in entropy (delta-S) is the change in heat (Q) divided by the absolute temperature (T): delta-S  Ã‚  Q/T In any reversible thermodynamic process, it can be represented in calculus as the integral from a processs initial state to its  final state of dQ/T. In a more general sense, entropy is a measure of probability and the molecular disorder of a macroscopic system. In a system that can be described by variables, those variables may assume a certain number of configurations. If each configuration is equally probable, then the entropy is the natural logarithm of the number of configurations, multiplied by Boltzmanns constant: S kB  ln W where S is entropy, kB is Boltzmanns constant, ln is the natural logarithm, and W represents the number of possible states. Boltzmanns constant is  equal to 1.38065 Ãâ€" 10−23  J/K. Units of Entropy Entropy is considered to be an extensive property of matter that is  expressed in terms of energy divided by temperature. The SI units of entropy are J/K (joules/degrees Kelvin). Entropy and the Second Law of Thermodynamics One way of stating the second law of thermodynamics is as follows: in any  closed system, the entropy of the system will either remain constant or increase. You can view this as follows: adding heat to a system causes the molecules and atoms to speed up. It may be possible (though tricky) to reverse the process in a closed system without drawing any energy from or releasing energy somewhere else to reach the initial state. You can never get the entire system less energetic than when it started. The energy doesnt have any place to go. For irreversible processes, the combined entropy of the system and its environment always increases. Misconceptions About Entropy This view of the second law of thermodynamics is very popular, and it has been misused. Some argue that the second law of thermodynamics means that a system can never become more orderly. This is untrue. It just means that to become more orderly (for entropy to decrease), you must transfer energy from somewhere outside the system, such as when a pregnant woman draws energy from food to cause the fertilized egg to form into a baby. This is completely in line with the second laws provisions. Entropy is also known as disorder, chaos, and randomness, though all three synonyms are imprecise. Absolute Entropy A related term is absolute entropy, which is denoted by S rather than ΔS. Absolute entropy is defined according to the third law of thermodynamics. Here a constant is applied that makes it so that the entropy at absolute zero is defined to be zero.

Read Emma Watsons 2016 UN Speech on Gender Equality

Read Emma Watson's 2016 UN Speech on Gender Equality Emma Watson, actor and UN Goodwill Ambassador, is using her fame and position with the United Nations to shine a spotlight on the problem of gender inequality and sexual assault at universities and colleges around the world. Watson made headlines in September 2014 when she launched a gender equality initiative called HeForShe with a rousing speech at the UN headquarters in New York. The speech focused on gender inequality around the world and the important role that men and boys must play in fighting for equality for girls and women. Speaking Out for Women In a more recent speech given at the UN headquarters in September 2016, Ms. Watson turned her attention to the gender double standards that many women encounter when they study and work at universities. Importantly, she connects this issue to the widespread problem of sexual violence that many women experience in the course of pursuing higher education. Ms. Watson, a proud feminist, also used the occasion to announce the publication of the first  HeForShe IMPACT 10x10x10 University Parity Report, which details the challenges of gender inequality and the commitments  to fighting them made by ten university presidents from around the world. The full transcript of her speech follows. Thank you all for being here for this important moment.  These men from all over the world have decided to make gender equality a priority in their lives and in  their universities. Thank you for making this commitment. I graduated from university four years ago. I had always dreamed of going and I know how fortunate I am to have had the opportunity to do so. Brown [University] became my home, my community, and I took the ideas and the experiences I had there into all of my social interactions, into my workplace, into my politics, into all aspects of my life. I know that my university experience shaped who I am, and of course, it does for many people. But what if our experience at university shows us that women dont belong in leadership? What if it shows us that, yes, women can study, but they shouldnt lead a seminar? What if, as still in many places around the world, it tells us that women dont belong there at all? What if, as is the case in far too many universities, we are given the message that sexual violence isnt actually a form of violence? But we know that if you change students experiences so they have different expectations of the world around them, expectations of equality, society will change. As we leave home for the first time to study at the places that we have worked so hard to get, we must not see or experience double standards. We need to see equal respect, leadership, and pay. The university experience must tell women that their brain power is valued, and not just that, but that they belong among the leadership of the university itself. And so importantly, right now, the experience must make it clear that the safety of women, minorities, and anyone who may be vulnerable is a right and not a privilege. A right that will be respected by a community that believes and supports survivors. And that recognizes that when one persons safety is violated, everyone feels that their own safety is violated. A university should be a place of refuge that takes action against all forms of violence. Thats why we believe that students should leave university believing in, striving for, and expecting societies of true equality. Societies of true equality in every sense, and that universities have the power to be a vital catalyst for that change. Our ten impact champions have made this commitment and with their work we know they will inspire students and other universities and schools across the world to do better. Im delighted to introduce this report and our progress, and Im eager to hear whats next. Thank you so much.