Energy in Chemical Reactions — Role & Overview
Read this topicExplanations 5
- Activation Energy Chemical reactions need something to get them going, whether it is heat, light, or flat out smacking the reactants with a hammer. That something is known as en…
By Deena Hauze, Alex Federspiel, Mario Janakis, Valeri Natole
- Law of Conservation of Energy Before we talk about anything else, we need to briefly go over the Law of Conservation of Energy. This law tells us that, in an isolated system (li…
By Hannah Bonville, Alex Federspiel, Deena Hauze, Mario Janakis, Valeri Natole
- What Is Activation Energy? Understanding the role that energy plays within a reaction is a powerful way to predict how it will react. This concept is most easily understood usin…
By Jasper Brown, Mario Janakis
- (Video) Exothermic and Endothermic Reactions by Cognito Energy: not just what coffee gives you in the morning. This video breaks down what energy looks like in different chemica…
By Valeri Natole, Mario Janakis
- (Video) What Triggers a Chemical Reaction? by Kareem Jarrah on TED-Ed Check out this video for a quick description of activation energy, exothermic reactions, and endothermic re…
By Mario Janakis
Problems 40
- Which of the following is an example of a reaction that absorbs heat?
- Which of the following is a good example of a reaction that gives off heat?
- The image above shows a type of reaction called single displacement. However, this particular reaction can occur rather slowly. Which of the choices below would not be successfu…
- Protein synthesis describes the reactions through which amino acids are joined together to make proteins. What is the role of enzymes in protein synthesis?
- How can this reaction best be classified?
- Which of the choices below best describes photosynthesis?
- In the diagram above, why does the energy go up during the reaction before it proceeds towards the products?
- Which of the graphs pictured above represents the energy diagram of an exothermic reaction?
- Which of the following statements is false regarding endothermic reactions?
- What is an exothermic reaction?
- Carefully examine the reaction diagram shown above. Choose the best labels for the numbered areas.
- Which of the following options is an example of an exothermic chemical reaction?
- Select the endothermic reactions from the options below.
- What conditions must be met in order for a reaction to be spontaneous?
- Which of the following statements are true for a reaction with a net positive change in energy?
- The energy released during an exothermic reaction can take which of the following forms?
- What is the energy needed to get a chemical reaction started called?
- Which of the following statements about energy in reactions is false?
- How to endothermic and exothermic reactions differ?
- How can we tell if there is a net decrease in energy for a chemical reaction?
- The activation energy of a reaction is typically not the same forward as backward. Which direction has the higher activation energy in the diagram above?
- If we know that a reaction is exothermic, and not entropically driven, what do we know about the reverse reaction?
- A catalyst increases reaction rate by loweringactivationenergy‾\underline{\phantom{lowering activation energy}}loweringactivationenergy.
- Which are examples of exothermic processes?
- When a strong electric current passes through water, it absorbs energy from the electricity and forms oxygen and hydrogen. 2H2O→O2+2H22H_{2}O\rightarrow O_{2}+2H_{2}2H2O→O2+2H…
- The decomposition of hydrogen peroxide into water and molecular oxygen occurs very slowly. The reaction can be sped up through the addition of catalase. How does catalase functi…
- There's nothing quite like sitting around a campfire late at night and watching the blinding sparks fly as you feel the heat in your bones. Where is the energy for that light an…
- If burning a sample of wood releases 5 kilojoules of energy, and our reaction is exothermic with an activation energy of 7 kilojoules, will the reaction occur?
- Whether energy is given off or consumed by a reaction is determined by which bonds are broken and which bonds are formed. When a bond forms, energy is expelled, and when a bond …
- There are three reactions. Reaction 1 releases 5 kilojoules of energy, reaction 2 releases 3 kilojoules, and reaction 3 absorbs 2 kilojoules. Which reaction is endothermic?
- When hydrogen absorbs 13.6 eV, it ionizes. H→H++e−H\rightarrow H^{+}+e^{-}H→H++e− If we assume that all the energy is in the form of heat, is this reaction endo- or exothermic?
- At high temperatures matter will begin to spontaneously fluoresce (blackbody radiation). In order to fluoresce, the matter must first be put into an excited state. Is heat-induc…
- If AAA is the activation energy and ΔH\Delta HΔH is the energy difference between the products and reactants (ΔH<0\Delta H < 0ΔH<0 implies energy released), which reaction will …
- A simple molecule is heated to 500∘C500^{\circ} C500∘C at which point it decomposes into 2 different molecules. This reaction is most likely endothermic‾\underline{\phantom{endo…
- On the rare occasion that the temperatures are forecasted to fall below freezing in Florida, orange farmers spray their oranges with water so that it will freeze. Why do they do…
- The formation of rust is an incredibly exothermic, spontaneous reaction. Why does iron not continuously emit intense heat due to rust formation?
- Examine the reaction coordinate diagram above. What is the activation energy?
- A certain reaction has an activation energy of 4.8325 KJ and releases 3.3376 KJ to the surroundings. How much energy does the reverse reaction release to the surrounding
- Consider the reactions below A+B→C+DΔH=5KJC→E+FΔH=−2KJG→DΔH=−1KJ\begin{align} A+B &\rightarrow C+D \quad &\Delta H=5KJ \\ C &\rightarrow E+F \quad &\Delta H=-2KJ \\ G &\rightarr…
- If reaction 111 is used to supply the activation energy in the form of heat for reaction 222, what do we know about reaction 111?