Chemical Reactions

Science, Grade 8

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© Copyright NewPath Learning. All Rights Reserved. 94-4805 www.newpathlearning.com + + + + + C + O2 CO2 2H2 + O2 2H2O 2H2O 2H2 + O2 Zn + 2HCl ZnCl2 + H2 NaCl + AgF NaF + AgCl H2O C6H12O6 Potassium chloride added to a silver nitrate solution forms a solid precipitate. Chemical Reactions Signs of Chemical Reactions A chemical reaction is a process in which one or more substances change to produce one or more new ones. Chemical reactions happen all around us lighting a match, rusting of an iron bar, or the tarnishing of a silver spoon. Chemical Formulas A chemical formula uses symbols to identify the elements in a compound and the number of atoms of each kind present in a molecule. A water molecule is made up of 2 atoms of hydrogen bonded to 1 atom of oxygen. A glucose molecule is made up of 6 atoms of carbon, 12 atoms of hydrogen, and 6 atoms of oxygen. Chemical Equations A chemical equation uses chemical formulas and symbols to describe a chemical reaction. The starting materials in a chemical reaction are reactants. The resulting substances from a reaction are products. The reactants are always placed on the left of the arrow, and the products on the right of the arrow. Types of Chemical Reactions Synthesis Reaction In a synthesis reaction, two or more simple substances combine to form a compound. For example, hydrogen gas combines with oxygen gas to produce water! Decomposition Reaction In a decomposition reaction, a compound breaks down into its simpler parts. A decomposition reaction is the reverse of synthesis reaction. For example, water decomposes to form hydrogen gas and oxygen gas. Replacement Reaction Single Replacement In a single replacement reaction, a single uncombined element replaces another in a compound. The products of such a reaction are a new compound and a different element. For example, zinc replaces the hydrogen in hydrochloric acid to form zinc chloride and hydrogen gas. Double Replacement In a double replacement reaction, ions from two compounds switch places to form two new compounds. For example, silver nitrate reacts with sodium chloride to form two new compounds - silver chloride and sodium fluoride. water color change gas formation solid formation glucose reactants reactant + reactant product reactant product + product reactant + reactant product + product reactant + reactant product + product product A gas is formed when copper is added to nitric acid. These simple shapes combine to form a new object. The fish shape breaks down into simpler forms. NaOH, added to Phenol- phthalein solution causes a color change. NaOH
© Copyright NewPath Learning. All Rights Reserved. 94-4805 www.newpathlearning.com + + + + + Zn + 2HCl ZnCl2 + H2 H2O C6H12O6 NaCl + AgF NaF + AgCl 2H2O 2H2 + O2 reactant product + product reactant + reactant product + product reactant + reactant product + product 2H2 + O2 2H2O reactant + reactant product Chemical Reactions Signs of Chemical Reactions What is a chemical reaction? ____________________________ _____________________________________________________ _____________________________________________________ Chemical Formulas A chemical formula uses ____________________ to identify the ____________________ in a compound and the ______________________________ of each kind present in a molecule. A water molecule is made up of _______ atoms of ____________________ bonded to _______ atom of ____________________ . A glucose molecule is made up of _______ atoms of ___________________ , _______ atoms of ___________________ , and _______ atoms of ____________________ . Chemical Equations A chemical equation uses ____________________ ____________________ and ____________________ to describe a chemical reaction. The starting materials in a chemical reaction are ____________________ . The resulting substances from a reaction are ____________________ . The ____________________ are always placed on the left of the arrow, and the ____________________ on the right of the arrow. Types of Chemical Reactions Synthesis Reactions Describe a synthesis reaction: ___________________________________ ___________________________________ ___________________________________ ___________________________________ Decomposition Reactions Describe a decomposition reaction: _____________________________________ _____________________________________ _____________________________________ _____________________________________ _____________________________________ Replacement Reactions Single Replacement Describe a single replacement reaction: _____________________________________ _____________________________________ _____________________________________ _____________________________________ _____________________________________ Double Replacement Describe a double replacement reaction: _____________________________________ _____________________________________ _____________________________________ _____________________________________ water glucose These simple shapes combine to form a new object. The fish shape breaks down into simpler forms. C + O2 CO2 Key Vocabulary Terms atom chemical equation chemical formula chemical reaction compound decomposition reaction double replacement reaction element product reactant single replacement reaction synthesis reaction Synthesis Reaction Decomposition Reaction Replacement Reaction \|xiBAHBDy01799ozX