Be Able to Balance Chemical Equations Using Coefficients

VOCABULARY Assignment

Use the Two-column Notes format/strategy to study/complete your vocabulary assignment.

OBJECTIVES:

Be able to balance chemical equations using coefficients.

Be able to identify and write the five basic types of equations: single displacement, double displacement, synthesis, decomposition and combustion.

Be able to use correct notation in equations (such as state symbols).

Be able to identify the seven diatomic molecules and use them correctly in equations.

Be able to use the activity series to write equations

SYMBOLS USED IN CHEMICAL EQUATIONS (brief descriptions and table listed below)

State symbols (after formula) s, l, g or aq (book uses cr for crystalline solid)

up arrow (↑) gas

down arrow (↓) ppt

reversible rxn

squiggly line above arrow = electric current or with e- as shown below above arrow = heat

temp, pressure may be written above arrow

catalyst may be written below or above arrow

Unit 8 Packet - Page 2 of 18

Unit 5 PROBLEM SET – Chemical Equations:

Follow the instructions for the cover page for Problem Sets.

Show your work on all problems. Credit will not be given without work.

Include units on your answers.

Review Questions:

1. Name the following:

1. FeSO4

1. BaCl2
2. CO

1. NH4NO2

1. Write the formula for the following:

1. diphosphorus trisulfide

1. cobalt (III) carbonate

1. silver sulfide

1. Nicotine, a component of tobacco, is 74.1 percent C, 8.6 percent H and 17.3 percent N by mass; the molar mass is about 162.5 g. What is nicotine’s empirical formula? Its molecular formula?

1. A. How many formula units in 78.3 g of lead (II) phosphate?

1. Calculate the molarity of a 1.5 liter solution of 498.6 g of lead (II) phosphate.

1. Calculate the percent composition of aluminum dichromate.

Current Unit Material:

1. Write balanced equations for the following reactions:

1. Calcium metal is added to water.

1. A solution of tin (II) chloride is added to a solution of iron (III) sulfate

1. Chlorine gas is bubbled into a solution of lithium iodide.

1. C3H8 is burned in oxygen

1. How is 2Cl different from Cl2 ?

1. Octane, C8H18, is a component of gasoline. Write the balanced equation for the complete combustion of octane. (extra credit)

1. The poisonous gas, hydrogen sulfide, can be neutralized with a base such as NaOH producing water and sodium sulfide. A student asked to write a balanced equation for the reaction wrote the following:

Na2OH(aq) + H2S (g) Na2S (aq) + H2O (l)

1. Is this equation correct?

B. Explain why or why not, and supply the correctly balanced equation if necessary.

Unit 8 Packet - Page 3 of 18

CHEMICAL EQUATIONS AND REACTIONS

Chemical Equation: represents with symbols and formulas the reactants and products

Equations must:

Represent known facts – all reactants and products must be included Contain correct formulas

Coefficients: numbers in front of compounds/elements

Represents the number of moles

Subscripts: numbers in the formulas

They are never changed!

Symbols used in equations are on your objective sheet !

WRITING AND BALANCING EQUATIONS

Diatomic molecules: Occur in pairs in their natural state (when they are alone and not ionic, not in compounds) – Notice there are 7 of these and they make a 7 shape on the PT!!!!!

Memorize!! (quiz):

Writing & Balancing Equations

Diatomic molecules –

occur in pairs in their natural state

(when they are alone; not in compounds)

I2, Br2, Cl2, F2, O2, N2, H2 (*Quiz*)

I Bring Clay For Our New House

or

His Brown Clown Found No Oranges Inside

Unit 8 Packet - Page 4 of 18

When writing equations you must satisfy the law of conservation matter

(matter can not be created or destroyed)

Therefore we must have the same type and number of each atom on each side of the equation.

BALANCING EQUATIONS: 4 steps:

1. Start with a word equation

1. Convert to a formula equation (don’t forget the diatomic molecules!)

1. Balance with coefficients:

balance each atom one at a time

balance polyatomic ions on each side of the equation as one unit balance H and O last (they often appear in more than one compound)

4. Check; if coefficients are not the lowest possible; reduce down.

*****Remember NEVER change subscripts***** Examples:

1. water breaks down into hydrogen and oxygen

2. aluminum carbide reacts with water to produce methane gas (CH4) and aluminum hydroxide

3. Na2SO4 + LiCl Li2SO4 + NaCl

You try:

1. calcium oxide reacts with bromine to make calcium bromide and oxygen

2. Ba(NO3)2 + PbO2 BaO + Pb(NO3)4

Unit 8 Packet - Page 11 of 18

WRITING CHEMICAL EQUATIONS

Write balanced equations for the following reactions after identifying the type of reaction.

1. aluminum sulfate + calcium phosphate

1. magnesium chloride + manganese (III) nitrate

1. Hydrogen gas + oxygen gas

1. Strontium metal + copper (II) nitrate

1. copper (II) oxide + sulfuric acid

1. nitrogen gas + lithium metal

1. C4 H8 + O2

1. sodium bromide + oxygen gas

1. copper (II) nitride (heated)

1. potassium metal + water

1. C3 H8 + oxygen gas

1. ammonium sulfate + sodium chloride

1. NiO + S

Unit 8 Packet - Page 12 of 18

REACTION TYPES

1. Synthesis: (or composition):

2 or more substances combine to form 1 new substance

A + X AX

Ex’s:

1. Decomposition:

A single substance produces 2 or more simpler substances

AX A + X

Ex’s:

Electrolysis:

Ex:

1. Single Displacement (Replacement):

1 element replaces a similar element in a cmpd

A + BX AX + B

Ex’s:

Unit 8 Packet - Page 13 of 18

1. Double Displacement (Replacement):

The ions of 2 cmpds switch places to form 2 new cmpds.

AX + BY AY + BX

*often one of the new cmpds will be a ppt.

Ex’s:

5. Combustion:

When a substance combines with oxygen releasing a large amount of energy in the form of light and heat.

Often combustions involve a hydrocarbon : cmpd containing C and H

CxHy + O2 CO2 + H2O

Ex.

Group Practice: ID, Write & Balance the following equations:

1. C2H4 + O2

1. Barium + Copper (II) chloride

1. O2 + Ca

1. PbCl4 + Al(NO3)3

1. CaCl2

Unit 8 Packet - Page 14 of 18

Double Displacement Reactions & Solubility Rules:

Solubility Rules:

Answer the following questions in the space provided.

1. Use your solubility rules to determine if the following substances are soluble (S) or insoluble (I) in water.

Practice Writing Dissolution of Solids Equations:

Write the net ionic equation for the dissolution of the following compounds.

Sample: BaCl2 (s) Ba+1(aq) + 2Cl-1(aq)

1. Na3PO4 (s)

1. K2SO4 (s)

1. KOH (s)

1. CaI2 (s)

1. Mg(NO3)2 (s)

Unit 8 Packet - Page 15 of 18

Net Ionic Equations:

Unit 8 Packet - Page 16 of 18

Solubility Rules and Net Ionic Equations Worksheet

Steps for writing a net ionic equation

1. Write a balanced equation.

1. Use your solubility rules to determine solubility and break soluble compounds into ions (with charges!). Leave insoluble compounds together without any charges!

1. Cancel out spectator ions – if everything cancels write no net reaction.

1. Write the final equation – include state symbols!

Example 1:

AgNO3 + MgCl2

Which of the following compounds are soluble in water? RbOH CrCO3 PbCl2 TiI BaS

Which of the following compounds are insoluble in water? NH3 (g) Ba(OH)2 PbI2 CaSO4 K2SO3

Write net ionic equations for the following reactions: 1. Ba(NO3)2 + Na2SO4 BaSO4 + 2 NaNO3

KC2H3O2

(NH4)3PO4

Example 2:

HNO3 + Ba(OH)2

You try:

K2S + Al(NO3)3

2. sodium hydroxide + zinc (II) nitrate sodium nitrate + zinc (II) hydroxide

3. PbCl2 + Na2SO4

4. Silver nitrate and calcium bromide

Unit 8 Packet - Page 17 of 18

5. sulfuric acid and sodium chloride produce hydrochloric acid and sodium sulfate

6. LiOH + H2S

7. aluminum chloride and iron (III) nitrate

1. ammonium chloride + potassium hydroxide potassium chloride + ammonia (g) + water

9. rubidium carbonate + strontium acetate

Unit 8 Packet - Page 18 of 18

Activity Series

Pg 265-267

1. What is the activity series

1. Where are the most active elements found in the series?

1. Look at the sample Questions 8-6 on pg 266 then do the practice questions

1. Do the section review 1-2 on page 267.

Activity Series Practice

(Use the series for single displacement reactions or synthesis reactions with oxygen):

I. Based on the activity series of metals and halogens, circle the element within each pair that is more likely to replace the other in a compound?

II. Using the activity series of metals and halogens, predict whether each of the possible reactions listed below will occur. For the reactions that will occur, write the products and balance the equation:

Ni(s) + CuCl2(aq)

Zn(s) + Pb(NO3)2(aq)

Cl2(g) + KI(aq)

Cu(s) + FeSO4(aq)

Ba(s) + H2O(l)

Na2SO4(aq) + Ba(NO3)2(aq)

CuCl2(aq) + Mg(NO3)2(aq)

III. Use the activity series to predict whether each of the following synthesis reactions will occur, and write the chemical equations for those predicted to occur:

Ca(s) + O2(g)

Ni(s) + O2(g)

Au(s) + O2(g)