Chapter 11 Chemical Reactions and Equations

Word Equations

Recall that ___________________________ can describe chemical reactions.

• Reactants are written to the ___________________ of the arrow and products are

written to the _____________ of the arrow.

• Recall how to name and write formulas from your _________________.

• A _________________________ is the formulas of the reactants and products

without the amounts included.

Balancing Chemical Equations

• ________________________________ do not require amounts but in order to

use actual equations in chemistry, a ________________________ with amounts must be

written.

Law of Conservation of Mass

• Chemical reactions must obey the _________________________________.

• Reactants must ____________________l the products in amount and mass.

• A __________________________________ compares the amounts of reactants

to products.

• An Example….

• We need two wheels to make a toy car.

• They are sold only in twos.

• Each toy car has one car body (Cb) and 4 wheels are necessary. (W4)

• What would be our balanced chemical equation for the toy car?

Building a Tricycle….

• Again, we need one trike body (Tb) but a tricycle has 3 wheels (W3) and the

wheels only come in packages of two. (W2)

• How many orders of each tricycle should be make so there are no leftover parts?

• Write a balanced “chemical” equation.

Tips and Tricks…

• If there is a ____________________________ on both sides of the equation, keep

it together and balance it as one atom.

• Balance the more ________________________ compounds first.

• The elements that are by themselves should be balanced last.

• Sometimes it is helpful to create a _________________ below the equation to

keep track of the numbers.

• If you have a word equation, write the ____________________________ first,

then balance.

LET’S PRACTICE!

• Balance the equations.

• AgNO3 + H2S Ag2S + HNO3

• Zn(OH)2 + H3PO4 Zn3(PO4)2 + H2O

• Iron(III) chloride + calcium hydroxide iron(III) hydroxide + calcium chloride

Types of Chemical Reactions

• There are ________ general types of reactions.

• Occasionally, a reaction may fit equally into __________ categories.

• ____________________ is useful to help determine and predict the products.

Combination Reactions

• It is also called a ______________ reaction.

• ________________________ substances combine to create a _______________

new substance.

• Mg + O2 MgO

• K + Cl2 KCl

• Balance these equations!

Draw a picture example of a combination reaction.

Decomposition Reactions

• A ______________ compound breaks down into ___________________ simpler

products.

• HgO Hg + O2

• H2O H2 + O2

• Balance these equations!

Draw a picture example of a decomposition reaction.

Single-Replacement Reaction

• One element ________________ a second element in a compound.

• Requires the ________________________ to determine if the reaction will occur.

• The element that is ___________________ on the series will replace any lower

elements.

• A ___________________ (group 7) can replace any other halogen providing that

it is higher up on the periodic table.

• If a reaction doesn’t occur, write _____________ for no reaction.

Single-Replacement Reactions

• K + H2O KOH + H2

• Zn + Cu(NO3)2 Cu + Zn(NO3)2

• Br2 + NaI NaBr + I2

• Br2 + NaCl NR

• Balance these equations!

Draw a picture example of a single-replacement reaction.

Double-Replacement Reactions

• Sometimes when two solutions are mixed, ____________________________.

• Other times, the _____________ in the two solutions react.

• In these types of reactions, the two ______________ (positive) cations

_______________ places with each other.

• Occasionally, a ________________ will form or a gas will be generated.

• Sometimes, both products are _________________ so you won’t see anything

different

Double-Replacement Reactions

• Na2S + Cd(NO3)2 CdS + NaNO3

• NaCN + H2SO4 HCN + Na2SO4

• Ca(OH)2 + HCl CaCl2 + H2O

• Balance these equations!

Draw a picture representing a double-replacement Reaction.

Combustion Reactions

• This is a chemical change that takes place when a compound (usually a

hydrocarbon) reacts with ________________ and produces _________________,

_______________ and usually ____________________ in the form of heat and/or light.

• C8H18 + O2 CO2 + H2O

• When balancing, these numbers are usually high.

Draw a picture showing a combustion reaction.

Reaction in Aqueous Solution

• Your world is water-based.

• Most reactions take place in _______________.

• Most equations can show the reactions between compounds but do not show how

the compounds _________________ when dissolved in water.

• They actually separate into the __________________________ when in aqueous

solution.

• You can use these ions to write a _________________________.

• If the ion remains ________________ on both sides of the equation, it is called a

_____________________.

• The ____________________ doesn’t participate in the reaction directly and can

be _______________________.

• The resulting equation is called the ________________________.

• Remember, the resulting equation must be ________________________.

Net Ionic Equations

• A net ionic equation shows only those ___________________ involved in the

reaction and is balanced with respect to both ______________ and _______________.

• Pb (s) + 2Ag+ (aq) 2Ag (s) + Pb +2 (aq)

• There are 2 Ag on both sides and +2 on both sides.

Solubility

• _______________ means it can dissolve in water or be _________________.

• There are rules to determine if something is soluble or not.

• Page. 344 table 11.3 has the rules.

• If something is soluble write _____________

• If it isn’t soluble or is insoluble, it is solid or _____________

• Check the table for the rules.

LET’S PRACTICE!

• Balance this equation.

• Ca+2 + OH- + H+ + PO4-3 Ca+2 + PO4

-3 + H2O

LET’S PRACTICE!

• Write the complete and net ionic equations for:

• Sodium hydroxide (aq) and phosphoric acid (aq) makes calcium phosphate and

water.

• Don’t forget to use your solubility rules.