Chemical Reactions Chemical Equations

Chemical Equations More than 200,000 words in the English language Trillions of substances that make up the universe The alphabet of chemistry

Chemical Equations The language of chemistry Element symbols H, O, Na, Fe Alphabet of chemistry

Chemical Equations Element symbols H, O, Na, Fe Compound formulas H 2 O, CO 2, NaCl Alphabet of chemistry Words of chemistry The language of chemistry

Chemical Equations Element symbols H, O, Na, Fe Compound formulas H 2 O, CO 2, NaCl Chemical equations 2H 2 + O 2 2H 2 O Alphabet of chemistry Words of chemistry Sentences of chemistry The language of chemistry

Chemical Equations Chemical equations 2H 2 + O 2 2H 2 O Sentences of chemistry Reactants Products chemical equation: an expression that describes the changes that happen in a chemical reaction. Chemical reactions tell a story

Chemical Equations Consider one reaction that takes place in a fire:

Chemical Equations Consider one reaction that takes place in a fire: Carbon (from wood) reacts with oxygen (from the atmosphere) to produce carbon dioxide gas

Chemical Equations Consider one reaction that takes place in a fire: Carbon (from wood) reacts with oxygen (from the atmosphere) to produce carbon dioxide gas carbon + oxygen

Chemical Equations Consider one reaction that takes place in a fire: Carbon (from wood) reacts with oxygen (from the atmosphere) to produce carbon dioxide gas carbon + oxygen carbon dioxide

Chemical Equations Consider one reaction that takes place in a fire: carbon + oxygen carbon dioxide C + O 2 CO 2

Chemical Equations Consider one reaction that takes place in a fire: carbon + oxygen carbon dioxide C + O 2 CO 2 Reactants Products

Chemical Equations Consider one reaction that takes place in a fire: carbon + oxygen carbon dioxide C + O 2 CO 2 Reactants Products separates the reactants arrow points toward the products

Chemical Equations Consider one reaction that takes place in a fire: C + O 2 CO 2 1 mole

Chemical Equations Consider one reaction that takes place in a fire: C + O 2 CO 2 1 mole x 12 g/mole 1 mole x 32 g/mole 1 mole x 44 g/mole

Chemical Equations Consider one reaction that takes place in a fire: C + O 2 CO 2 1 mole x 12 g/mole = 12 g 1 mole x 32 g/mole = 32 g 1 mole x 44 g/mole = 44 g

Chemical Equations Consider one reaction that takes place in a fire: C + O 2 CO 2 1 mole x 12 g/mole = 12 g 1 mole x 32 g/mole = 32 g 1 mole x 44 g/mole = 44 g Total mass of reactants = 44 g Total mass of products = 44 g

Chemical Equations 1 mole x 12 g/mole = 12 g 1 mole x 32 g/mole = 32 g 1 mole x 44 g/mole = 44 g Total mass of reactants = 44 g Total mass of products = 44 g C + O 2 CO 2

Chemical Equations Reaction that fuels the space shuttle: Hydrogen burns with oxygen to produce water The “white smoke” is actually water vapor

Chemical Equations hydrogenoxygenwater+ Reaction that fuels the space shuttle: Hydrogen burns with oxygen to produce water

Chemical Equations hydrogen H 2 oxygen O 2 water H 2 O ++++ Reaction that fuels the space shuttle:

Chemical Equations hydrogen H 2 oxygen O 2 water H 2 O Reaction that fuels the space shuttle:

Chemical Equations hydrogen H 2 oxygen O 2 water H 2 O Reaction that fuels the space shuttle: 2 hydrogen atoms 2 oxygen atoms 2 hydrogen atoms 1 oxygen atom

Chemical Equations hydrogen H 2 oxygen O 2 water H 2 O Reaction that fuels the space shuttle: 2 hydrogen atoms 2 oxygen atoms 2 hydrogen atoms 1 oxygen atom

Chemical Equations Hydrogen H 2 Oxygen O 2 Water H 2 O hydrogen atoms 2 oxygen atoms 2 hydrogen atoms 1 oxygen atom This chemical equation is not balanced: it violates the law of conservation of mass

Chemical Equations From Chapter 4.2 2H22H2 Subscript tells how many atoms in 1 molecule Hydrogen gas

Chemical Equations From Chapter 4.2 2H22H2 Coefficient tells how many molecules are involved Hydrogen gas

Chemical Equations Subscript tells how many atoms in 1 molecule From Chapter 4.2 2H22H2 Coefficient tells how many molecules are involved Hydrogen gas When balancing a chemical equation, only coefficients can be changed Subscripts remain the same

Chemical Equations 2H2O23H2O2H2O23H2O 2 hydrogen molecules 1 oxygen molecule 3 water molecules Coefficients MoleculesAtoms

Chemical Equations 2H2O23H2O2H2O23H2O 2 hydrogen molecules 1 oxygen molecule 3 water molecules Coefficients MoleculesAtoms

Chemical Equations 2H2O23H2O2H2O23H2O 2 hydrogen molecules 1 oxygen molecule 3 water molecules Coefficients MoleculesAtoms

Chemical Equations The balanced chemical equation: 2H 2 + O 2 2H 2 O ReactantsProducts Molecules Atoms

Chemical Equations

Chemical Equations The glucose (C 6 H 12 O 6 ) contained in biomass is used as biofuel to produce (C 2 H 6 O) and carbon dioxide (CO 2 ). Write the balanced equation for this reaction.

Chemical Equations The glucose (C 6 H 12 O 6 ) contained in biomass is used as biofuel to produce (C 2 H 6 O) and carbon dioxide (CO 2 ). Write the balanced equation for this reaction. Asked:The coefficients needed to balance the chemical equation Given:The unbalanced chemical equation C 6 H 12 O 6 → C 2 H 6 O + CO 2 Relationships:The same number of each type of atom must appear on each side.

Chemical Equations The glucose (C 6 H 12 O 6 ) contained in biomass is used as biofuel to produce (C 2 H 6 O) and carbon dioxide (CO 2 ). Write the balanced equation for this reaction. Asked:The coefficients needed to balance the chemical equation Given:The unbalanced chemical equation C 6 H 12 O 6 → C 2 H 6 O + CO 2 Relationships:The same number of each type of atom must appear on each side. Solve:All atoms involved in the reaction are unbalanced. There are 6 C atoms, 12 H atoms, and 6 O atoms in the reactants. There are 3 C atoms, 6 H atoms, and 3 O atoms in the products. From this accounting, we notice that the number of atoms in the products is half the number of atoms in the reactants.

Chemical Equations The glucose (C 6 H 12 O 6 ) contained in biomass is used as biofuel to produce (C 2 H 6 O) and carbon dioxide (CO 2 ). Write the balanced equation for this reaction. Asked:The coefficients needed to balance the chemical equation Given:The unbalanced chemical equation C 6 H 12 O 6 → C 2 H 6 O + CO 2 Relationships:The same number of each type of atom must appear on each side. Solve:All atoms involved in the reaction are unbalanced. There are 6 C atoms, 12 H atoms, and 6 O atoms in the reactants. There are 3 C atoms, 6 H atoms, and 3 O atoms in the products. From this accounting, we notice that the number of atoms in the products is half the number of atoms in the reactants. By multiplying the products by a factor of 2 we obtain a balanced chemical equation of the reaction.

Chemical Equations The glucose (C 6 H 12 O 6 ) contained in biomass is used as biofuel to produce (C 2 H 6 O) and carbon dioxide (CO 2 ). Write the balanced equation for this reaction. Asked:The coefficients needed to balance the chemical equation Given:The unbalanced chemical equation C 6 H 12 O 6 → C 2 H 6 O + CO 2 Relationships:The same number of each type of atom must appear on each side. Solve:All atoms involved in the reaction are unbalanced. There are 6 C atoms, 12 H atoms, and 6 O atoms in the reactants. There are 3 C atoms, 6 H atoms, and 3 O atoms in the products. From this accounting, we notice that the number of atoms in the products is half the number of atoms in the reactants. By multiplying the products by a factor of 2 we obtain a balanced chemical equation of the reaction. Answer:The balanced chemical equation is C 6 H 12 O 6 → 2C 2 H 6 O + 2CO 2.

Chemical Equations 2H22H2 Coefficient tells how many molecules are involved Subscript tells how many atoms in 1 molecule When balancing a chemical equation, only coefficients can be changed Subscripts remain the same