Chemical Equations

A Quick Review… Chemical symbol: A shorthand notation for an element’s name. A shorthand notation for a compound or a molecule. Chemical formula:

A Quick Review… Chemical reaction: The process by which one or more substances undergo change to produce one or more different substances. Writing out a chemical reaction can take a long time and isn’t universal, so there exists a simpler way to represent a chemical reaction called a…

Chemical Equations Chemical equation: A shorthand notation of a chemical reaction using chemical formulas and symbols. Example: C+O2O2 CO 2

Parts of a Chemical Equation C+O2O2 CO 2 Reactants: the starting materials in a chemical reaction. (LEFT) - Written before the arrow. Products: the substances formed in a reaction. (RIGHT) - Written after the arrow.

Parts of a Chemical Equation C+O2O2 CO 2 Plus sign: reads: ‘reacts with’. Carbon reacts with dioxide Arrow: Reads ‘to produce’ or ‘to yield’ Carbon reacts with dioxide to yield Carbon dioxide.

Why We Counted Atoms C+O2O2 CO 2 The number of atoms we start with (reactants side) must equal the number of atoms we end up with (products side). All equations must be balanced. The number of atoms of each element in a reactant must equal the number of the same elements in the product. Reactants = Products

Why We Counted Atoms C+O2O2 When counting atoms for each side, think of the yield sign as an equal sign. C+O2O2 O2O2 = The number of Carbon in the reactants must equal the number of Carbon in the product. The number of Oxygen in the reactants must equal the number of Oxygen in the product. C O2O2 C

Balancing the Equation C+O2O2 O2O2 C Divide the equation into a chart.

Balancing the Equation C+ O O2O2 C Count the number of atoms of each element on the reactants side using symbols to represent the number of atoms. C O2O2 O Are all atoms counted for on the left side? If so, we can move to the right side of the arrow.

Balancing the Equation C+ O O2O2 C Repeat the same process for the right side as you did with the left side. C O2O2 O OC O

Balancing the Equation C+ O O2O2 C Start with Carbon and count each side. C O2O2 O OC O 1 1 Do we have an equal amounts of Carbon? Let’s move on to Oxygen

Balancing the Equation C+ O O2O2 C Now Count the Oxygen on each side. C O2O2 O OC O 2 Do we have an equal amounts of Oxygen? We have a BALANCED equation. 2

Balancing the Equation C + O2O2 C O2O2

C + O2O2 C O2O2

A Balanced Equation C + O2O2 C O2O2

Balancing Example H2H2 +O2O2 OH2H2 Dihydrogen reacts with Dioxide to yield Dihydrogen monoxide.

Balancing Example H2H2 +O2O2 OH2H2 H H O O Count the number of atoms of each element on the reactants side using symbols to represent the number of atoms.

Balancing Example H2H2 +O2O2 OH2H2 H H O O Repeat the same process for the right side as you did with the left side. H H O

Balancing Example H2H2 +O2O2 OH2H2 H H O O H H O Start with Hydrogen and count each side. Do we have an equal amounts of Hydrogen? 2 2

Balancing Example H2H2 +O2O2 OH2H2 H H O O H H O Now count Oxygen on each side. Do we have equal amounts of Oxygen? 2 1

Balancing Example H2H2 + O2O2 O H2H2 We cannot leave an equation unbalanced. What can be done to fix it?

Balancing Example H2H2 +O2O2 OH2H2 H H O O H H O HHO

The equation is still unbalanced. What can be done to fix it? H2H2 + O2O2 O H2H2

Balancing Example H2H2 +O2O2 OH2H2 H H O O H H O Are Oxygen atoms equal on both sides? HHO Are Hydrogen atoms equal on both sides? Let’s try and fix Hydrogen. H H

Balancing Example H2H2 +O2O2 OH2H2 H H O O H H O The number of boxes represents the coefficient. HHO What is the coefficient in front of H 2 ? H H What is the coefficient in front of H 2 O? 221

A Balanced Equation H2H2 +O2O2 OH2H2 221

Practice H2H2 +Cl 2 ClH H H H H 211 Dihydrogen reacts with dichloride to yield Hydrogen monocholoride.

Practice N2N2 +H2H2 H3H3 N N N H H NHHH NHHH H H H H 321 Dinitrogen reacts with dihydride to yield Nitrogen trihydride.

Practice Na+Cl 2 F2F2 NaCl+F NaFCl NaFCl FNaClNaF 2121 Sodium Fluoride reacts with Dichloride to yield Sodium Chloride and Difluoride