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Chemical Reaction- When substances change chemically to form a new substance. 1. Forms new bonds between atoms. 2. Make new substances 3. Example- 2 hydrogen atoms (gas) +1 oxygen atom (gas) react to form 1 water molecule (h20) How do you know a reaction occurred? 1. A gas is produced and the chemical starts to bubble. 2. The chemical changes color. 3. The temperature of the chemical changes from before. What happens in a reaction? 1. Reactants react to create a product. Reactants- the materials that exist before the chemical reaction Products- Substances that are created by the chemical reaction 2. In a reaction atoms are arranged and no new atoms are created.
Energy is needed to break chemical bonds so they can start a chemical reaction. Energy is released when bonds form. Chemical Energy- energy that is stored in atoms and molecules. Chemical energy can be released during a reaction. Potential Energy can be thought of as energy stored within a physical system. It is called potential energy because it has the potential to be converted into other forms of energy, such as kinetic energy. Activation Energy- the energy needed by a system to initiate a particular process. Often used to denote the minimum energy needed for a specific chemical reaction to occur. Endothermic- Photosynthesis is an example of an endothermic reaction. Plants use the energy to form the sun to convert carbon dioxide and water into the glucose and oxygen. Exothermic- Mixture of sodium and chlorine to yield table salt. This reaction produces 411 (kj) of energy for each mole of salt that is produced. ralchemistry
Exothermic processes Making ice cubes Formation of snow in clouds Condensation of rain from water vapor A candle flame Mixing sodium sulfite and bleach Rusting iron Burning sugar Forming ion pairs Combining atoms to make a gas phase Mixing water and strong acids Mixing water with an anhydrous salt Crystallizing liquid salts Nuclear fission Mixing water with calcium chloride Endothermic processes Melting ice cubes Conversion of frost to water vapor Evaporation of water Forming a cation from an atom in the gas phase Baking bread Cooking an egg Producing sugar by photosynthesis Separating ion pairs Splitting a gas molecule apart Mixing water and ammonium nitrate Making an anrous salt from a hydrate Melting solid salts Reaction of barium hydroxide crystals with dry ammonium chloride Reaction of thionyl chloride (SOCl2) with cobalt(II) sulfate heptahydrate Exothermic Reactions- Reactions that releases energy and the temperature gets hotter. Endothermic Reactions- Reactions that absorbs energy and the temperature gets colder.
Synthesis Reaction- two or more simple substances combine to form a more complex substance. Decomposition Reaction- a more complex substance breaks down into its more simple parts 1 reactant yields or more products. Reactions are opposite. Single Replacement- a single uncombined element replaces another in a compound. Double Replacement- parts of two compounds that switches places to forms two new compounds. Combustion Reaction- always involves molecular oxygen. Anytime anything burns it is a combustion reaction.
Synthesis Reaction A + B AB Two materials, elements or compounds, come together to make a single product. Some examples of synthesis reactions are: Hydrogen gas and oxygen gas burn to produce water. Decomposition Reaction XZ = X + Z Some examples of decomposition reactions are: potassium chlorate when heated comes apart into oxygen gas and potassium chloride Single Replacement 2 AgNO3 + Cu Cu(NO3)2 + 2 Ag The element replaces one of the ions in the solution and a new element appears from the ion in solution. Double Replacement AgNO3 + KCl AgCl(s) + KNO3 Dissolved silver nitrate becomes a solution of silver ions and nitrate ions. Potassium chloride ionizes the same way. When the two solutions are added together, the silver ions and chloride ions find each other and become a solid precipitate.
WRITE THE FORMUAL FOR EACH MATERIAL 1. sulfur trioxide and water combine to make sulfuric acid. 2. lead II nitrate and sodium iodide react to make lead iodide and sodium nitrate. 3. calcium fluoride and sulfuric acid make calcium sulfate and hydrogen fluoride (Hydrofluoric acid) 4. calcium carbonate will come apart when you heat it to leave calcium oxide and carbon dioxide. 5. ammonia gas when it is pressed into water will make ammonium hydroxide. 6. sodium hydroxide neutralizes carbonic acid 7. zinc sulfide and oxygen become zinc oxide and sulfur. 8. lithium oxide and water make lithium hydroxide 9. aluminum hydroxide and sulfuric acid neutralize to make water and aluminum sulfate. 10. sulfur burns in oxygen to make sulfur dioxide. 11. barium hydroxide and sulfuric acid make water and barium sulfate. 12. aluminum sulfate and calcium hydroxide become aluminum hydroxide and calcium sulfate. 13. copper metal and silver nitrate react to form silver metal and copper II nitrate. 14. sodium metal and chlorine react to make sodium chloride. 15. calcium phosphate and sulfuric acid make calcium sulfate and phosphoric acid. 16. phosphoric acid plus sodium hydroxide. 17. propane burns (with oxygen) 18. zinc and copper II sulfate yield zinc sulfate and copper metal 19. sulfuric acid reacts with zinc 20. acetic acid ionizes. 21. steam methane to get hydrogen and carbon dioxide 22. calcium oxide and aluminum make aluminum oxide and calcium 23. chlorine gas and sodium bromide yield sodium chloride and bromine