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Warm Up January 7, 2013. Suppose you are making s’mores and each s’more requires 2 graham crackers, one large marshmallow, and 3 squares of chocolate. If you have 4 marshmallows, how many can you make? If you have 18 squares of chocolate, how many can you make?
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Warm Up January 7, 2013 • Suppose you are making s’moresand each s’more requires 2 graham crackers, one large marshmallow, and 3 squares of chocolate. • If you have 4 marshmallows, how many can you make? • If you have 18 squares of chocolate, how many can you make? • If you have 11 graham crackers, how many can you make?
Agenda • Warm Up • Types of Reactions & Balancing Equations Notes • Chemical Reaction Lab Part 2 • Pass Back Exam 3 • Cool Down • HW: • Exam 3 Corrections (optional) • 6.2 Vocabulary Booklet (words AND sentences) (8 words on p. 224) • Finish Chemical Reactions Lab Part 2
Chemical Equations • Reactants – the substances that exist before a chemical change (or reaction) takes place. • Products – the new substance(s) that are formed during the chemical changes. • CHEMICAL EQUATION indicates the reactants and products of a reaction. REACTANTS PRODUCTS
Types of Reactions • There are three main categories of chemical reactions.
Synthesis • Synthesis reactions combine 2 or more reactants to produce one product. • Example:
Decomposition • Decomposition reactions break down one reactant into more than one product.
Replacement • Replacement reactions are when one element switches places with or replaces another element in a compound.
What Type of Reaction? Replacement
What Type of Reaction? Synthesis
What Type of Reaction? Decomposition
What Type of Reaction? Replacement
What Type of Reaction? Synthesis
What Type of Reaction? Synthesis
What Type of Reaction? Decomposition
What Type of Reaction? Decomposition
What Type of Reaction? Replacement
Meaning of Chemical Formula Chemical Symbol Meaning Composition H2O One molecule of water: Two H atoms and one O atom 2 H2O Two molecules of water: Four H atoms and two O atoms H2O2 One molecule of hydrogen peroxide: Two H atoms and two O atoms
Law of Conservation of Matter • Matter cannot be created or destroyed in ordinary chemical reactions, but it can change forms.
Cl H H H Cl Cl Cl H reactants products reactants products H H Cl Cl Unbalanced and Balanced Equations H Cl Cl Cl H H H2 + Cl2 2 HCl (balanced) (unbalanced) H2 + Cl2 HCl 2 1 2 2 1 2 2 2
Balancing Chemical Equations • Write the equation. • Count the atoms. • Use coefficients to balance atoms. • Check! Coefficients are the big numbers in front of chemical compounds in an equation.
Cool Down • Balancing Equations Sequencing Map