Chemical Reactions

SC StandardsPS-4.6 Distinguish between chemical changes (including the formation of gas or reactivity with acids) and physical changes (including changes in size, shape, color, and/ or phase).

PS-4.7 Summarize characteristics of balanced chemical equations (including conservation of mass and changes in energy in the form of heat-that is, exothermic or endothermic reactions).

PS-4.8Summarize evidence (including the evolution of gas; the formation of a precipitate; and/ or changes in temperature, color, and/ or odor) that a chemical reaction has occurred.

PS-4.9Apply a procedure to balance equations for a simple synthesis or decomposition reaction.

PS-4.10Recognize simple chemical equations (including single replacement and double replacement) as being balanced or not balanced.

PS-4.11Explain the effects of temperature, concentration, surface area, and the presence of a catalyst on reaction rates.

Signs of a Chemical ReactionProduction of lightFormation of a gasFormation of a precipitateColor changeChange in temperature

Law of Conservation of Massmass is neither created nor

destroyed in a chemical reaction

4 H

2 O4 H

2 O

4 g 32 g

36 g

total mass stays the sameatoms can only rearrange

Chemical Equations

A+B C+DREACTANTS PRODUCTS

Chemical Equations

Types of Chemical Reactions

Synthesisthe combination of 2 or more

substances to form a compound

only one product

A + B AB

Synthesis

H2(g) + Cl2(g) 2 HCl(g)

Decompositiona compound breaks down into 2

or more simpler substances

only one reactant

AB A + B

Decomposition2 H2O(l) 2 H2(g) + O2(g)

Single Replacementone element replaces another in a

compoundmetal replaces metal (+)nonmetal replaces nonmetal (-)

A + BC AC + B

Single Replacement

Cu(s) + 2AgNO3(aq) Cu(NO3)2(aq) + 2Ag(s)

AB + CD AD + CB

Double Replacementions in two compounds “change partners”cation of one compound combines with

anion of the other

Double Replacement

Pb(NO3)2(aq) + K2CrO4(aq) PbCrO4(s) + 2KNO3(aq)

Double Replacement Reaction Lab