chemical formulae, types of reactions, chemical equations, and balancing
TRANSCRIPT
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Chemical Formulae, Types of Reactions,Chemical Equations,
and Balancing
![Page 2: Chemical Formulae, Types of Reactions, Chemical Equations, and Balancing](https://reader036.vdocuments.us/reader036/viewer/2022081504/56649e405503460f94b30e58/html5/thumbnails/2.jpg)
Chemical Formulae
• Indicates the # of atoms of each type in a molecule or the ratio of the # of atoms of each type in a compound
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• Worksheet to practice writing chemical formulae
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Types of Chemical Reactions
• Chemical reactions are chemical changes in which new substances are formed.
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Synthesis Reaction
• 2 or more simple substances combine to form a more complex substance
• These reactions come in the general form of: A + B ---> AB
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Eg. Synthesis Reaction
• Hydrogen gas combined with oxygen gas can produce a more complex substance water!
• The chemical equation for this synthesis reaction looks like:
2H2 + O2 2H2O Reactant + reactant product
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Decomposition Reaction
• A more complex substance breaks down into its more simple parts. One reactant yields 2 or more products.
• These reactions come in the general form:
AB ---> A + B
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Eg. Decomposition Reaction
• Water can be broken down into hydrogen gas and oxygen gas. The chemical equation for this decomposition reaction looks like:
2H2O 2H2 + O2
reactant product + product
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Single Replacement Reaction
• A single uncombined element replaces another in a compound. Two reactants yield two products.
• These reactions come in the general form of: A + BC ---> AC + B
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Eg. Single Replacement Reaction
• Zinc combines with hydrochloric acid, the zinc replaces hydrogen. The chemical equation for this single replacement reaction looks like:
Zn + 2HCl ZnCl2 + H2
reactant + reactant product + product
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Double Replacement Reaction
• Parts of two compounds switch places to form two new compounds. Two reactants yield two products.
• These reactions are in the general form:
AB + CD ---> AD + CB
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Eg. Double Replacement Reaction
• Silver nitrate combines with sodium chloride, two new compounds - silver chloride and sodium nitrate are formed because the sodium and silver switched places. The chemical equation for this double replacement reaction looks like: AgNO3 + NaCl AgCl + NaNO3
reactant + reactant product + product
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Combustion
• Oxygen combines with another compound to form water and carbon dioxide.
• Eg. CH4(g) + 2O2(g) 2H2O(g) + CO2(g)
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Acid - Base
• Acid and base react with each other. The H+ ion in the acid reacts with the OH- ion in the base, causing the formation of water.
• The product of this reaction is salt and water: HA + BOH ---> H2O + BA
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Eg. Acid - Base
• Reaction of hydrochloric acid and sodium hydroxide to form sodium chloride and waterHCl + NaOH ---> NaCl + H2O
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• Questions to review 6 types of reactions
• Possibly get students to work in groups to learn types of reactions– Matching questions = definition of each
reaction, match up to an example
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Chemical Equations
• A way of writing the changes in a chemical reaction
• Reactants combine and produce new chemical substances – products– Reactants Products
• The # and type of atoms in the reactants should always be equal to the # and type of atoms in the products
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Chemical Equations Cont’d
H2(g) + O2(g) H2O(l) 2H2(g) + O2(g) 2H2O(l)
2 2 2 1 4 2 4 2
• Symbols in brackets = state– s = solid– l = liquid– g = gas– aq = aqueous
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Balancing Chemical Equations!
• Balanced chemical equations tells you the ratio in which the elements are combined and produced
• A chemical equation is balanced when the number of atoms of each type on each side of the equation is the same.
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How to Balance an Equation1. Start with word equation and name reactants and
productsEg. methane gas + oxygen gas carbon dioxide + water
2. Replace the words with formulae and rewrite equationEg. CH4 + O2 CO2 + H2O
3. Count # atoms of each elementElement Reactants Products C 1 1 H 4 2 O 2 3
4. If # atoms on both sides are not equal, need to balance the equation
Eg. CH4 + 2O2 CO2 + 2H2O
5. Add physical state symbolsEg. CH4(g) + 2O2(g) CO2(g) + 2H2O(l)
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• Worksheet with balancing equation questions