Bell Work 11-30-15

• What do you use to convert grams to moles or moles to grams?

• What do you use to convert particles(atoms, molecules, units) to moles or vice versa?

• If I am changing from grams to particles what do I need to do?

• Convert 184g of PbI2 to particles.

Extra Credit-Memes!• Create a meme that is related to chemistry. • To create a meme, go to a meme generator

website. Choose a blank meme and add your own text.

• After you have created a meme save the image. Either email me or print the image.

• You need to include 2-3 sentences describing the science behind your meme and why it is funny and clever.

• DUE BY MONDAY, DECEMBER 7

Unit 6: Chemical Reactions

What are indications that a chemical reactions has

happened?

Bell Work 12-1-15

• List 5 things that would indicate a chemical reaction has occurred.

Indicators of chemical reactions

Formation of a gas

Emission of light or heat

Formation of a precipitate

Color change

Emission of odor

All chemical reactions:Have two parts

1. Reactants - the substances you start with

2. Products- the substances you end up with

The reactants turn into the productsReactants ® Products

Describing Chemical Reactions

Can be described several ways: 1. In a sentence

Copper reacts with chlorine to form copper (II) chloride.

2. In a word equationCopper + chlorine ® copper (II) chloride

Cu + Cl2 ® CuCl2

Symbols used in equations(s) after the formula –solid Cu(s)

(g) after the formula –gas H2 (g)

(l) after the formula -liquid H2O(l)

(aq) after the formula - dissolved in water, an aqueous solution. CaCl2 (aq)

Cu(s) + Cl2(g) ® CuCl2(aq)

Symbols used in equations indicates a reversible reaction

shows that heat is supplied to the reaction

heat , ® ®

Diatomic elementsThere are 7 elements that never want to be alone.They form diatomic molecules, in gas state.

H2 , N2 , O2 , F2 , Cl2 , Br2 , and I2

Law of Conservation of MassIn a chemical reaction, matter is neither created nor destroyed.

Atoms won’t change their identity (e.g. a Carbon atom can’t become an Iron atom)

This means that you have to have the same number of each type of atom on each side of the chemical equation.

Law of Conservation of Mass• Atoms cannot be created or destroyed!

• Total mass stays the same.• The atoms are rearranged to form new materials.

Balancing EquationsWe can see that the equation, does not follow the Law of Conservation of Mass

C2 + O2 CO2

We can see that on the product side there are two carbon atoms, but on the reactant side there is only one. This cannot possibly happen, as mass cannot be destroyed

Balancing Equations

• To balance chemical equations follow these basic steps

1. Perform an atom inventory—count how many of each element you have on each side of the arrow.

2. Identify your problem areas3. Begin adjusting the coefficients of the

equation to balance the equation. You cannot change the subscripts, only the coefficients!

Balancing Equations

C2 + O2 CO2

1. Atom inventory

2. Identify Problems3. Fix Problems

WARNING!Don’t mess with the insides of polyatomic ions – put a square around them, or label them as X – treat the WHOLE polyatomic ion as though it were an element!

Don’t ever play around with subscripts (those little numbers that tell you how many atoms are in a molecule)

e.g. C6H22O11

H2 + Cl2 ® HCl

1H2 + 1Cl2 ® 2HCl

7.

CdCO3 ® CdO + CO2

Already Balanced

8.

Li + FeBr2 ® LiBr + Fe 4.

2Li + 1FeBr2 ® 2LiBr + 1Fe

KClO3 ® KCl + O2

3.

2KClO3 ® 2KCl + 3O2

NaOH + FeCl3 ® NaCl + Fe(OH)3

3NaOH + 1FeCl3 ® 3NaCl + 1Fe(OH)3

5.

Na + H2O ® NaOH + H2

2Na + 2H2O ® 2NaOH + 1H2

2.

Ca2Br2 + NaCO3 ® CaCO3 + NaBr

1Ca2Br2 + 2NaCO3 ® 2CaCO3 + 2NaBr

6.

Bell Work 12-6-15Balance the following equations:

1.___Al2(SO4)3 +___ Ca(OH)2 →__ Al(OH)3 + __ CaSO4

2. ___Cr +___ O2 →____ Cr2O3

Types of Reactions1. Synthesis reactions2. Decomposition reactions3. Single displacement reactions4. Double displacement reactions5. Combustion reactions

1. SynthesisExample C + O2

OO C + ® O O C

General: A + B ® ABDefinition: multiple reactants combine to form a single product http://www.youtube.com/watch?v=uCwHzTsx5yY

2. DecompositionExample: NaCl

General: AB ® A + B

®Cl Na Cl + Na

Definition: breakdown of one molecule into elements or simple compounds http://www.youtube.com/watch?v=ImWpJienMRA

3. Single Displacement/Replacement

Example: Zn + CuCl2

® ZnClCl Cu +

General: AB + C ® AC + B

ClCl Zn Cu+

Definition: an element or ion is replaced by another in a compound

4. Double displacementExample: MgO + CaS

General: AB + CD ® AD + CB

SO®Mg Ca+

O S

Mg Ca+

Definition: two elements or ions are replaced by another in multiple compounds

5. Combustion ReactionsDefinition: a hydrocarbon reacts with oxygen gas.This is also called burning!!!

In general: CxHy + O2 CO2 + H2OProducts are ALWAYS carbon dioxide and water.

Bell Work 12-8-151.Balance the equation 2. What type of reaction?

1. _____ Ca + _____ O2 ® _____ CaO Reaction: _______________

2. _____ Cu2O + _____ C ® _____ Cu + _____ CO2

Reaction: _______________

3. _____ Na + _____ MgF2 ® _____ NaF + _____ MgReaction: _______________

4. _____ Na + _____ HCl ® _____ H2 + _____ NaClReaction: _______________

5. _____ Cl2 + _____ KI ® _____ KCl + _____ I2

Reaction: _______________

Activity Series. Elements will replace elements below them in single rep. reactions. K Ca NaMgAl Zn Fe Ni Pb HCuAg

Ion Solubility ExceptionsNO3

– soluble noneClO4

– soluble none

Cl– soluble except Ag+, Hg2

2+, *Pb2+

I– soluble except Ag+, Hg22+, *Pb2+

SO42- soluble except Ca2+, Ba2+, Sr2+, Hg2+, Pb2+,

Ag+ CO3

2- insoluble except Group IA and NH4+

PO43- insoluble except Group IA and NH4

+

OH– insoluble except Group IA, *Ca2+, Ba2+, Sr2+

S2- insoluble except Group IA, IIA and NH4+

Na+ soluble noneK+ soluble noneNH4

+ soluble none

Solubility Table

AgNO3(aq)

CuSO4(aq)

Li3N

NH4NO3