Chemical Reactions

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Chemical Reactions

Chemical Reactions!!

By,Grace MosierDue:March 3,2015

But How Do We Know That a Chemical Reaction occurred?

Types of Chemical Reactions:-Synthesis Reaction- A+B--->AB Two separate elements combine to make one element. Example- 2Na+Cl2--->2NaCl ; Sodium + Chlorine ---> Sodium Chloride-Decomposition Reaction- AB--->A+B The reactant, containing 2+ different elements, is broken up into the different elements. Example- 2NaCl--->2Na+Cl2 ; Sodium Chloride ---> Sodium + Chlorine-Combustion Reaction-A [reactant A is a fuel, often with carbon and hydrogen)+O2--->CO2+H2O Some type of fuel, often containing carbon and hydrogen, combines with oxygen, with the addition of heat, and produces carbon dioxide and water. Example- CH4+2O2+heat--->CO2+2H2O ; Methane + Oxygen ---> Carbon Dioxide + Water-Rearranging Reaction-Single replacement: A+BC--->AC+B An element not connected to anything is switched with another that is connected to another element. Example- [Zn]+[H2]SO4--->[Zn]SO4+[H2] ; Zinc + Sulfuric acid (Hydrogen,Sulfur,Oxygen) --> Zinc Sulfate + HydrogenDouble replacement: AB+CD--->CB+AD An element connected to another element switches with another element that is connected to another element; either both metals or both non-metals. Example- [Ag]NO3+[Na]Cl--->[Na]NO3+[Ag]Cl ; Silver Nitrate + Sodium Chloride ---> Sodium Nitrate + Silver Chloride

There are a few pieces of evidence that indicate a chemical reaction has occurred:1.Color change-when two different colored substances combine, an the product produced is a third color. Example~ Gray iron rusts, and the product is brown.2.Formation of Precipitate- when two liquid reactants comine and a solid product, or precipitate, is formed. Example~ A sea creature releases a sepcial liquid, and it reacts with the seawater to form a shell.3.Formation of Gas- when two reactants form a gas. Example~ An antacid pill is swallowed and mixes with stomach acid, which forms gas.4.Temperature Change- when two or more reactants' temperatures rise or drop during a chemical reaction. Example~ Concrete becomes warm before it hardens.

Physical Properties:Reactants-[hydrogen and oxygen] Oxygen is a colorless, odorless gas. The density of oxygen is 0 at 0°C and 1.429 grams/liter normally, and becomes a liquid at -182.96°C. Hydrogen is also a colorless, odorless gas. Its density is 0.08999 grams/liter, and becomes a liquid at -252.77°C.Products-[water] Water is a clear liquid, with a boiling/melting point of 100°C at sea level, and the density of water is a little bit less than 1.

How Are the Properties of the Reactants Different Than the Properties of the Products?

Chemical Properties:Reactants-[Oxygen and Hydrogen] Oxygen supports combustion, combines with elements at room temperature, and reacts with many different compounds. It's atomic number is 8 and is located in group 16. Bond type- covalentHydrogen easily combines with other non-metals and the halogens in group 17. Its atomic number is 1 and is located in group 16. Bond type- covalent/hydrogenProducts- [water] Water has a slightly negative charge, and the bonds between molecules are very strong. Water is a very popular and good solvent, and conducts little to no electricity, unless an ionic compund is dissolved in it. Bond type- hydrogen bond

The Chemical/Physical Properties of the Synthesis of Water! (A synthesis reaction)O2+2H2->2H2O

The properties of the reactants are very different than that of the products. Firstly, oxygen is good for combustion before the reaction, but the product, water, is not. Additionally, the bond type of oxygen is covalent, and the bond type of water is a hydrogen bond. For physical properties, both oxygen and hydrogen are gases, and water is a liquid. The melting/boiling points and the density change in the reaction as well.

Video of the Synthesis of Water

Endothermic and Exothermic Reactions Information


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