A minimum amount of energy is required to start a chemical reaction. What is this energy called?Activation energyEndothermic energyReaction energyExothermic energy2On a reaction profile, what does the difference between the reactants line and the products line represent?The energy changeThe activation energyThe temperature changeThe amount of product formed3If the energy change on a reaction profile goes down, what does this tell you about the reaction?It is exothermicMore heat is requiredThere is not enough reactantIt is endothermic4Which of the following statements about endothermic reactions is true?They do not require any activation energyThe products will always have less energy than the reactantsThe products will always have more energy than the reactantsThe products will always have the same energy as the reactants

The minimum amount of energy that is needed to start a chemical reaction is called

1. The minimum amount of energy that is needed to start a chemical reaction is called ___________________________.2. A chemical reaction in which a substance combines with oxygen and releases energy is called ________________.3. A chemical reaction that releases thermal energy is called _____________________.4. Chemical reactions that absorb thermal energy are called ____________________.5. A __________________________________reaction in one in which the two negative ions in two compounds switch places, forming two new compounds.6. A chemical reaction in which one element replaces another element in a compound is called ____________________.7. A substance that increases reaction rate by lowering the activation energy of a reaction is called _______________.8. A __________________ reaction is one where one compound breaks down and forms two or more substances.9. A ___________________reaction is one in which two or more substances combine and form one compound.10. A substance that slows, or even stops a chemical reaction is called a ____________________.11. The starting substances in a chemical reaction are the ____________________.12. A ________________________________________ is a process in which atoms of one or more substances rearrange to form one or more new substances.13. The substances produced by the chemical reaction are the ______________________.14. A number placed in front of an element symbol or chemical formula in an equation is called a __________________.15. This states that the total mass of the reactants before a chemical reaction is the same as the total mass of the products after the chemical reaction. __________________________________________16. Breaking a chemical bond _____________ energy from the surroundings.17. Mass is conserved in a chemical reaction because ____________________________.18. Catalysts are _____________________________changed during chemical reactions.19. Chemical reactions can be sped up by doing what?20. How would you slow down a chemical reaction?

Because energy is _____ in an exothermic reaction, the products are lower in energy than the reactants.

E. Mark each description as an exothermic or endothermic reaction. (2 points) Description Exothermic Endothermic A + heat B–ΔHEnergy diagram:Energy of reactants greater than energy of products

Which of the following describes an exothermic reaction?A.Hf, reactants = 0B.Hf, reactants = Hf, productsC.Hf, reactants > Hf, productsD.Hf, reactants < Hf, products