Daily Writing Tips is Now Mobile Friendly

Daily Writing Tips is Now Mobile Friendly Daily Writing Tips is Now Mobile Friendly Daily Writing Tips is Now Mobile Friendly By Maeve Maddox Over the past month we have been rolling out a new design on Daily Writing Tips. The goal was to make the layout cleaner and to optimize the visualization on mobile devices. Now you can visit our website with any smartphone, tablet or computer, and the layout will adapt itself automatically to your screen size and resolution. In addition, we have implemented some server optimizations that should reduce the load time of our pages. This improvement will ensure that users on low bandwidth connections will have a pleasant experience on the site.   The rollout is complete, but if you find anything that is not working as intended, please let us know. If you’re an email subscriber and have not visited the website in a while, come on over and check out the new design!   Pro Subscription The new site improvements also benefit Pro subscribers because the resources offered inside the members area have been optimized for mobile devices. Pro subscribers can go through the interactive exercises on any smartphone or tablet now. This is a great way to review previous exercises and quizzes in the Pro archives. If you’re not a Pro subscriber, you are missing out! Here’s what you get as a Pro subscriber: Each day’s complete writing tip in your electronic mailbox. A daily exercise with explanations of a basic concept related to English grammar, diction, or punctuation. Access to an archived collection of 300+ interactive exercises and quizzes to test your understanding of standard English usage. Click here to start a free trial of the Pro subscription. Social Media You may not be aware that Daily Writing Tips is present on the most popular social networks. You can visit us at Facebook.com/DailyWritingTips. â€Å"Like† our fan page to receive alerts on your Facebook account whenever we publish a new article. You can also follow us on Twitter (@writing_tips) to receive daily updates. Daily Writing Tips appears on several lists that feature the â€Å"best websites for writers.† We’re proud of our contribution to the language blogging community. And we’re proud of our updated new look. We hope you like it too. Want to improve your English in five minutes a day? Get a subscription and start receiving our writing tips and exercises daily! Keep learning! Browse the General category, check our popular posts, or choose a related post below:Inquire vs Enquire40 Fish IdiomsTreatment of Words That Include â€Å"Self†

How to Calculate Activation Energy

How to Calculate Activation Energy Activation energy is the amount of energy that needs to be supplied in order for a chemical reaction to proceed. The example problem below demonstrates how to determine the activation energy of a reaction from reaction rate constants at different temperatures. Activation Energy Problem A second-order reaction was observed. The  reaction rate constant at three degrees Celsius was found to be 8.9 x 10-3 L/mol and 7.1 x 10-2 L/mol at 35 degrees Celsius. What is the activation energy of this reaction? Solution The  activation energy can be determined using the equation:ln(k2/k1) Ea/R x (1/T1 - 1/T2)whereEa the activation energy of the reaction in J/molR the ideal  gas constant 8.3145 J/K ·molT1 and T2 absolute temperatures (in Kelvin)k1 and k2 the reaction rate constants at T1 and T2 Step 1: Convert temperatures from degrees Celsius to KelvinT degrees Celsius 273.15T1 3 273.15T1 276.15 KT2 35 273.15T2 308.15 Kelvin Step 2 - Find Ealn(k2/k1) Ea/R x (1/T1 - 1/T2)ln(7.1 x 10-2/8.9 x 10-3) Ea/8.3145 J/K ·mol x (1/276.15 K - 1/308.15 K)ln(7.98) Ea/8.3145 J/K ·mol x 3.76 x 10-4 K-12.077 Ea(4.52 x 10-5 mol/J)Ea 4.59 x 104 J/molor in kJ/mol, (divide by 1000)Ea 45.9 kJ/mol Answer: The activation energy for this reaction is 4.59 x 104 J/mol or 45.9 kJ/mol. How to Use a Graph to Find Activation Energy Another way to calculate the activation energy of a reaction is to graph ln k (the rate constant) versus 1/T (the inverse of the temperature in Kelvin). The plot will form a straight line expressed by the equation: m - Ea/R where m is the slope of the line, Ea is the activation energy, and R is the ideal gas constant of 8.314 J/mol-K. If you took temperature measurements in Celsius or Fahrenheit, remember to convert them to Kelvin before calculating 1/T and plotting the graph. If you were to make a plot of the energy of the reaction versus the reaction coordinate, the difference between the energy of the reactants and the products would be ΔH, while the excess energy (the part of the curve above that of the products) would be the activation energy. Keep in mind, while most reaction rates increase with temperature, there are some cases where the rate of reaction decreases with temperature. These reactions have negative activation energy. So, while you should expect activation energy to be a positive number, be aware that its possible for it to be negative as well. Who Discovered Activation Energy? Swedish scientist Svante Arrhenius proposed the term activation energy in 1880 to define the minimum energy needed for a set of chemical reactants to interact and form products. In a diagram, activation energy is graphed as the height of an energy barrier between two minimum points of potential energy. The minimum points are the energies of the stable reactants and products. Even exothermic reactions, such as burning a candle, require energy input. In the case of combustion, a lit match or extreme heat starts the reaction. From there, the heat evolved from the reaction supplies the energy to make it self-sustaining.