UNIT 8 Chemical Reactions Practice Problems 8... · UNIT 8 – Chemical Reactions Practice Problems...

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CRHS Academic Chemistry

UNIT 8 – Chemical Reactions

Practice Problems

Due Date Assignment On-Time (100) Late (70)

_____ 8.1 _________ ________

_____ 8.2 _________ ________

_____ 8.3 _________ ________

_____ 8.4 _________ ________

_____ 8.5 _________ ________

_____ 8.6 _________ ________

_____ Warm-Up _________ ________

_____ EC _________ ________

Notes, Homework, Exam Reviews and Their KEYS located on CRHS Academic Chemistry Website: https://cincochem.pbworks.com

of 36 Unit 8 Reactions

WARM-UPS

Unit 8 Notes of 36


HW 8.1 REACTIONS AND SKELETAL EQUATIONS

1. List the 4 indicators of a chemical change.

a) _______________________________________

b) _______________________________________

c) _______________________________________

d) _______________________________________

2. Give the meaning of each symbol:

_________________________ (s) ____________________________

__________________________ (l) _____________________________

__________________________ (g) ____________________________

__________________________ (aq) ____________________________

3. Using the Law of Conservation of mass, solve for the missing values.

a. Fe2O5 Fe + O2

304g 224g ____?

b. C7H16 + O2 CO2 + H2O

____? 352g 308g 144g

c. 2 Rb + 1 Br2 2 RbBr

Atoms Rb___ Atoms Rb___ Atoms Br___ Atoms Br___

4. Write the skeletal reaction from the following word reactions

a. Zinc metal reacts with silver nitrate powder to yield silver metal and zinc nitrate crystals

b. Solid lithium combines with solid sulfur to form lithium sulfide crystals

Δ

MnO

2

Unit 8 Notes of 36

c. Aqueous barium iodide is mixed with lithium phosphate to form aqueous lithium iodide and solid

barium phosphate

d. Solid manganese combines with bromine gas to form solid manganese (III) bromide

e. Cobalt metal combines with sulfur powder to form cobalt (II) sulfide crystals

f. Cesium oxide crystals decompose into cesium metal and oxygen gas

g. Potassium iodide crystals decompose into potassium metal and Iodine gas

h. Solid aluminum combines with nitrogen gas to form aluminum nitride crystals

i. Solid sodium metal is placed in a flask with gaseous chlorine to form sodium chloride

j. Bromine gas is reacted with solid potassium iodide to form iodine gas and potassium bromide crystals


HW 8.2 BALANCING EQUATIONS

Balance the following chemical reactions.

1. _______H2 + _______O2 ______H2O

2. _______Mg + _______Cl2 _______MgCl2

3. ______Ba + ______O2 _______BaO

4. ______Al + _______O2 ______Al2O3

5. ______Mn2O7 ______Mn + ______O2

6. ______H2 + _______N2 ______NH3

7. ___Na + ___O2 ___Na2O

8. ___Mg + ___P4 ___Mg3P2

9. ___K2O + ___H2O ___KOH

10. ___Al + ___CuO ___Al2O3 + ___Cu

11. ___SF6 ___S + ___ F2

12. ___C5H12 + ___O2 ___CO + ___H2O

Unit 8 Notes of 36

Balance the following chemical reactions.

1. ___F2 +___ Al2O3 ___AlF3 + ___O2

2. ___I2 + ___Na2S2O3 ___ NaI + ___Na2S4O6

3. ___ C2H6 +___ O2 ___ CO2 +___ H2O

4. ___ CaCl2 + ___AgNO3 ___ AgCl + ___Ca(NO3)2

5. ___ Al + ___CuSO4 ___Cu + ___Al2(SO4)3

6. ___C3H8 + ___O2 ___CO2 + ___H2O


HW 8.3 DECOMPOSITION & SYNTHESIS REACTIONS

Are the following reactions synthesis or decomposition? Fill in the blank and balance.

1. ___NaCl(s) ___Na(s) + ___Cl2(g) ___________________

2. ___H2(g) + ___O2(g) ___H2O(l) ___________________

3. ___BBr3 (s) ___B (s)+ ___Br2 (g) ___________________

Rewrite the following word equations as balanced chemical equations. Indicate synthesis or decomposition in

the blank.

4. Solid lithium combines with solid sulfur to form lithium sulfide crystals

______________________

Predict the products and balance the following reactions. Indicate synthesis or decomposition in the blank.

5. ___SF6 ______________________

6. ___Mg + ___Cl2 ______________________

7. ___Mn2O7 ______________________

8. ___Ba + ___O2 ______________________

Unit 8 Notes of 36

9. ___Al + ___O2 ______________________

10. Solid strontium combines with bromine gas to form…

_____________________

11. Cesium oxide crystals decompose into...

______________________


HW 8.4 COMBUSTION & SINGLE REPLACEMENT REACTIONS

Predict the products and balance the following combustion reactions.

1. ___C2H6(g) + ___O2(g)

2. ___Ca(s) + ___O2(g)

3. ___C6H14(g) + ___O2(g)

Identify the following reactions as Synthesis, Decomposition, Combustion, or Single Replacement. There may

be more than one correct answer.

4. Na + I2 NaI _______

5. CH3OH + O2 CO2 + H2O

6. MgO Mg + O2

7. F2 + CuBr2 Br2 + CuF2

8. Cobalt metal combines with sulfur powder to form cobalt (II) sulfide crystals

____________

9. Potassium metal reacts with chromium (IV) nitrate to form potassium nitrate and chromium metal.

__________________

Predict the products and balance the following single replacement reactions. Write “NR” if no reaction occurs.

10. ___K + ___Zn(NO3)2

11. ___FeCl3 + ___Mg

Unit 8 Notes of 36

12. ___Cl2 + ___AlBr3

13. ___Na + ___CaI2

Identify, predict the products, and balance the following reactions.

14. ___NH3

15. ___Al + ___Mg2P3


HW 8.5 REDOX REACTIONS

1. Given: Mg + Cl2 → MgCl2

a. Element being oxidized is ________ because there is a loss of ________ electrons. The change in oxidation

number is from ________ to ________ .

b. Element being reduced is ________ because there is a gain of ________ electrons. The change in oxidation

number is from ________ to ________ .

2. Which of the following reactions are redox reactions? (Show proof by labeling oxidation numbers.)

a. _____ Yes _____ No HCl + NaOH → NaCl + H2O

b. _____ Yes _____ No Fe + 2 HCl → FeCl2 + H2

c. _____ Yes _____ No NaI + Pb(NO3)2 → NaNO3 + PbI2

d. _____ Yes _____ No Mg + O2 → MgO

e. _____ Yes _____ No HgO → Hg + O2 3. Actions required for each of the following problem:

1. Identify the reaction type. 2. Predict products. 3. Balance the reaction. 4. Show oxidation numbers of all elements. 5. Indicate whether reaction is redox. 6. Place [Ox] above element in reactant that is oxidized and [Red] above element in reactant that is oxidized. The first problem is done for you.

Type of Reaction REDOX? (S, D, C, SR) (Y/N)

a. __SR___ __2_ Li + ___ SnCl2 → Sn + 2 LiCl __Y___

b. ______ ____ Sr + ____ S2 → _____

c. ______ ____ Cl2 + ____ NiBr2 → ______

-1 +2 -1 +1

0

0

[Ox] [Red]

Unit 8 Notes of 36

d. ______ ____ C2H6 + ____ O2 → ______

e. ______ ____ Fr2O → ______

f. ______ ____ Li + ___ Na3N → ______

g. _______ ____ Mn + ___ O2→ ______

h. _______ ____ Br2(g) + ____ MgI2 → _____

i. ______ ____ CH4 + ____ O2(g) → _____

j. _______ ___ Cs3P → ______


HW 8.6 DOUBLE REPLACEMENT REACTIONS: PRECIPITATION & ACID-BASE

Identify the following reactions as Synthesis, Decomposition, Combustion, Single Replacement, Acid-Base, or

Precipitation.

1. Li2CO3 + BaBr2 LiBr + BaCO3

2. Pentane (C5H12) burns with oxygen to form carbon dioxide and water.

3. F2 + Li LiF

4. Potassium iodide crystals are heated to form potassium metal and iodine gas

5. HNO3 + Ba(OH)2 Ba(NO3)2 + H2O

6. Bromine gas is reacted with solid potassium iodide to form iodine gas and potassium bromide

Predict the products and balance the following double replacement reactions. Write “NR” if no reaction

occurs.

7. ___Na3PO4 + ___MgCl2

8. ___K3PO4 + ___Sr(ClO4)2

9. ___PbSO4(aq) + ___(NH4)2S(aq)

10. ___Ca(OH)2 + ___(NH4)2S

11. ___BaCl2 + ___CuSO4

Unit 8 Notes of 36

Identify, predict the products, and balance the following reactions. Write “NR” if no reaction occurs.

12. ___AgNO3(aq) + ___NaCl(aq) _____

13. ___Rb(s) + ___Se _____

14. Iron (III) oxide is broken down…

_____

15. ___SnCl4(aq) + ___Cr(s) _____

16. Cs + I2 CsI _____

17. CH3CH2CH2OH + O2

18, MgO Mg + O2


8.1 REACTIONS AND SKELETAL EQUATIONS

Chemical Reactions

A chemical reaction is a process that changes a group of substances into a different

group of substances.

Evidence of a Chemical Change – (not proof, just evidence)

1. Energy exchange (temperature change, emission of light)

2. Change in color

3. Production of gas (odor, bubbles)

4. Formation of a precipitate

Precipitate: an insoluble product of a chemical reaction, usually a solid.

Chemical Equations

A chemical equation is a way to write a chemical reaction on paper.

They can give us a great deal of information:

o The substances that react – REACTANTS

o The substances produced – PRODUCTS

o The number of moles of each substance

A chemical equation is NOT like a math equation.

Reactants ≠ Products

Reactants “Become” Products

Chemical Equations Can Be Written 3 Ways:

1) Word Equation (this is why naming is critical!)

The equation in word form

Example: Solid sodium metal reacts with oxygen gas and yields solid sodium oxide and heat.

Unit 8 Notes of 36

2) Skeletal Equation

Formulas written but not balanced (no coefficients)

Example: Na(s) + O2 (g) Na2O (s) + heat

3) Balanced Equation

Formulas written and balanced

Example: _4_Na(s) + _1_O2 (g) _2_Na2O (s) + heat

Symbols – In writing reactions, we use many common symbols to indicate components of the reaction.

See also: the cover!

Symbol Meaning Symbol Meaning separates reactants & products (s) solid phase

yields or produces (l) liquid phase

heat is added (g) gaseous phase

reaction is reversible (aq) dissolved in water

To show a catalyst is added (ex: MnO2), write the catalyst above the reaction arrow:

The Law of Conservation of Mass

The Law of Conservation of Mass states that matter cannot be created or destroyed.

In equation form:

Mass of reactants = Mass of products

Equations must be balanced because of the Law of Conservation of Mass

So, there must be an EQUAL number of atoms of each element on each side of the chemical equation.

+

Δ

MnO2


Diatomic Gases

Diatomic gases are molecules composed of only the same two same atoms. The seven diatomic gases are H2, O2, F2,

Br2, I2, N2, Cl2. (Remember Dr. HOFBrINCl). In a reaction these elements need to be written as diatomic gases and

not as monoatomic elements.

Writing Skeletal Equations

1) Covalent compounds use prefixes (mono, di, tri, etc…), contain 2 or more nonmetals, and charges

do not need to be balanced”.

Example: …carbon dioxide gas = CO2 (g)

2) Any ionic compound (with polyatomic ion or transition metal) or acid must have charges balanced

to find the proper subscripts.

Example: … solid lithium oxide = (Li+1 O–2) Li2O_(s)__

3) Single Elements are written by themselves UNLESS they are diatomic molecules (H2, O2, F2, Br2, I2,

N2, Cl2). If diatomic, add a 2 subscript.

Examples: …argon gas = Ar …nitrogen gas = N2 (g)

4) Include the symbol for the state of matter. Keep in mind that a “crystal” or “metal” is a solid

5) The “reaction action” words tell you where the arrow goes. (produce, yield, make, form, creates…)

Example

Liquid ammonia (NH3) and oxygen gas burn to form nitrogen monoxide gas and water.

NH3 (l) + O2 (g) -> NO (g) + H2O

Unit 8 Notes of 36

Practice 1. Carbon monoxide gas reacts with oxygen gas to produce carbon dioxide gas. 2. Iron (III) oxide crystals react with gaseous carbon monoxide to form iron metal and carbon dioxide gas.

3. Potassium chlorate crystals decompose to yield solid potassium chloride and oxygen gas. 4. Liquid bromine and potassium iodide in solution react to form liquid iodine and potassium bromide in solution


8.2 BALANCING CHEMICAL EQUATIONS

Balancing Chemical Equations – There are two types of numbers in a chemical equation.

Subscript = the number of atoms of one part of a compound. Applies only to the

element/polyatomic ion it follows.

4 Na(s) + O2 (g) 2 Na2O(s

Coefficient = the number of atoms of the element or compound that it comes before. Applies to the entire substance.

Steps to Balancing Skeletal Equations

1. Make a table of each atom (or polyatomic ion) under the reaction arrow. Listing the elements a

single time under the reaction arrow is also an option.

2. Balance large compounds first then balance smaller compounds.

3. Balance diatomic molecules last.

4. Reduce all coefficients to lowest whole number ratio.

*** NEVER change subscripts, balance by changing coefficents,

*** Ensure that the number of atoms of each element is the same on both sides of the equation

*** Polyatomic ions appearing unchanged on both sides of the equation can be counted as a single unit

(like an element), example: KNO3 + LiCl LiNO3 + KCl

Example

Skeletal: H2 (g) + O2 (g) H2O (l)

Balanced: 2 H2 (g) + 1 O2 (g) 2 H2O (l)

2 4 #H 2 4

2 #O 1 2

LIST

Unit 8 Notes of 36

Practice

Skeletal: SO2 (g) + O2 (g) SO3 (g)

Balanced: ___ SO2 (g) + ___ O2 (g) ___ SO3 (g)

Skeletal: NaOH(aq)+ CaBr2 (aq) Ca(OH)2 (s) + NaBr(aq)

Balanced: ____ NaOH(aq)+_____CaBr2 (aq) _____ Ca(OH)2 (s) + _____ NaBr(aq) * Treat polyatomic ions like one element if intact on both sides of the equation

Skeletal: K2CrO4(aq)+ Pb(NO3)2(aq) KNO3(aq)+ PbCrO4(s)

Balanced: ___K2CrO4(aq) +____ Pb(NO3)2(aq) ____ KNO3(aq) + ____ PbCrO4(s)

* Treat polyatomic ions like one element if intact on both sides of the equation

Skeletal: C6H6 (l) + O2 (g) CO2 (g) + H2O (g)

Balanced: ____ C6H6 (l) + ____ O2 (g) _____ CO2 (g) + ______H2O (g)

Skeletal: C6H14 (l) + O2 (g) CO2 (g) + H2O (g)

Balanced: _____ C6H14 (l) + ______ O2 (g) ______ CO2 (g) + _____ H2O (g)


8.3 DECOMPOSITION AND SYNTHESIS REACTIONS

A. A DECOMPOSITION reaction is the splitting of a compound to form 2 or more simpler substances.

Example

1 Li2S (s) Li (s) + 1 Se (s)

1 reactant 2 products

Decomposition reactions often require energy in the form of light, heat, or electricity.

PREDICTING the PRODUCTS of Decomposition:

Remember HOFBrINCl

Do NOT bring subscripts over from reactants!

1. Binary compounds decompose into the two elements.

Example

2 H2O (l) 2 H2 (g) + O2 (g)

2 HgO (s) 2 Hg (l) + O2 (g)

Practice – predict the products and balance

1. ____ NaCl (s)

2. ____ Al2S3 (s)

3. ___ Na2O (s)

AB -> A + B DECOMPOSITION REACTION

heat

ricity

elect

ricity

heat

ricity

heat

ricity

heat

ricity

Unit 8 Notes of 36

B. A SYNTHESIS reaction is the combining of two or more substances to form a larger compound. This is the

OPPOSITE of Decomposition!

Example

2 Na(s) + 1 S(s) 1 Na2S(s)

2 reactants 1 product

PREDICTING the PRODUCTS of Synthesis: Combine the reactants to form a compound.

Don’t forget to Criss - Cross ionic compounds.

Do NOT bring subscripts over from reactants!

Example

_2_K(s) + _1_ I2 (g) _2 KI____


1. ____Al(s) + ____Cl2 (g)

2. ____ Na (s) + ____ O2 (g)

A + B AB SYNTHESIS REACTION


8.4 COMBUSTION AND SINGLE REPLACEMENT REACTIONS

A. COMBUSTION of a hydrocarbon is the burning of a hydrocarbon in the presence of O2 producing CO2,

H2O, and lots of heat.

Example

C5H12 (g) + 8 O2 (g) 5 CO2 (g) + 6 H2O (g)

PREDICTING the PRODUCTS of Combustion

A hydrocarbon is a made of C, H, and possibly oxygen (methane (CH4), butane (C2H6), octane (C8H8),

and others)

The reactants are always the hydrocarbon and O2.

The products are ALWAYS CO2 , H2O and heat.

Always balance a combustion staring with carbon, then hydrogen, and finally oxygen. If the

coefficient of the oxygen results in a oxygen coefficient with a 0.5, then multiply all coefficients by 2 to

get whole number for each.

Example

____CH4(g) + ____ O2(g) → _CO2__ + __H2O____


1. _____C4H10(g) + _____ O2(g) →

2. ___C4H10O(g) + ____ O2(g) →

CxHy + O2 CO2 + H2O CxHyOz + O2 CO2 + H2O

COMBUSTION OF A HYDROCARBON

Unit 8 Notes of 36

B. A SINGLE REPLACEMENT reaction is one in which one element takes the place of another.

Examples

2 Fe (s) + 1 CuCl2 (aq) 1 FeCl2 (s) + Cu (s)

Cl2 (g) + ZnBr2 (aq) Br2 (g) + ZnCl2 (aq)

The reactants will be an ionic compound and a metal or halogen.

A single metal will replace a metal.

A halogen will replace a halogen.

Replacement reactions are not reversible.

Q: How do we know if a reaction will occur?

A: We use the Activity Series for metals and Group 17 for halogens.

PREDICT the PRODUCTS of a Single Replacement Reaction:

1. Find the lone element in the reactants (metal/ halogen)

2. Compare to the like element in the ionic compound on the activity series (metals) or group 17

(halogens)

3. Metals can only replace metals that are less active, or lower than them on the activity series.

4. Halogens can replace halogens lower than them in group 17.

A + BX -> AX + B Y + BX -> BY + X SINGLE REPLACEMENT REACTION


5. If the lone element cannot replace it’s like element in the compound, then write “NR” as the product for “no

reaction”.

6. If it CAN replace:

a. Criss- Cross to form the new ionic compound.

b. Write the new lone element. Don’t forget HOFBrINCl!

Examples

Ba (s) + 2 ZnNO3 (aq) → Ba(NO3)2 (aq) + Zn (s)

Cl2 (g) + 2 LiBr (aq) → 2 LiCl (aq) + Br2 (g)

Practice – predict products and balance

1. ____Fe (s) + ____MgSO4 (aq) →

2. __Br2 (l) + ___ AlI3 (aq) →

3. ____Ca (s) + ____CuSO4 (aq) →

4. ____ Na (s) + ____ KBr (aq) →

Unit 8 Notes of 36


8.5 REDOX REACTIONS A REDUCTION-OXIDATION (Redox) reaction is a chemical reaction where the oxidation number of two elements change in the reaction.

Example of a redox reaction.

4 Li (s) + O2 (g) → 2 Li2O (s)

In this synthesis reaction the oxidation number of lithium went from zero on the reactant side of the reaction to +1 on the product side. The oxidation number of oxygen (O2) went from zero on the reactant side to -1 on the product side. An element is oxidized when the oxidation number of that element increases. Lithium was oxidized from 0 to +1 in the example problem. An element is reduced when the oxidation number of that element is reduced. Oxygen was reduced from 0 to -2 in the example problem. Hint: An easy way to identify whether a reaction is redox is to look for unbonded atoms or diatomic gases and recognize that the oxidation number is zero for each. Those elements cannot be zero on both sides of the reaction, so that reaction must be a redox reaction. Memory Aids: “OIL RIG” - Oxidation Is Loss (of e-1), Reduction Is Gain (of e-1) “LEO the lion goes GER” – Loss of Electrons is Oxidation, Gain of Electrons is Reduction

Oxidation and reduction always occur together because the Conservation of Mass applies to electrons. The total number of electrons lost by atoms being oxidized must equal the total number of electrons gained by all atoms being reduced..

Why are redox reactions important? Redox reactions involve the loss and gain of electrons and can be used to generate an electrical current, e.g. batteries. A type of redox reaction (combustion of hydrocarbons) provide energy for generation of power in cars and electrical power plants. Oxidation and reduction is instrumental in living systems including transport mechanisms across membranes and reactions that provide energy in mitochondria.

+1 -2 0 0

Oxidation Numbers Changed. Must be Redox

Reaction !

Unit 8 Notes of 36

What reactions are Redox Reactions? The four reactions that we studied in 8.3 and 8.4 (Synthesis, Decomposition of diatomic compounds, Combustion of a hydrocarbon, and Single Replacement) are examples of Redox Reactions.

Synthesis: 6 Li + N2 → 2 Li3N (Li0 is oxidized to Li+1) (N0 is reduced to N-3)

Decomposition: 2 NaCl → 2 Na + Cl2 (Na+1 is reduced to Na0) (Cl-1 is oxidized to Cl0))

Combustion: CH4 + O2 → CO2 + 2H2O (C-4 is oxidized to C+4) (O0 is reduced to O-2)

Single Replacement: Ba + NiCl2 → BaCl2 + Ni (Ba0 is oxidized to Ba+2) (Ni2 is reduced to Ni0)

How to calculate oxidation numbers of elements in formula’s?

Summary: Use the oxidation numbers that do not vary to calculate the oxidation number of element that is unknown.

Table of Oxidation Numbers That Do Not Vary.

Element or Group of Elements Examples Oxidation Number

Lone atoms (not bonded) S, Al, Ba 0

Diatomic Molecules (HOFBrNCl) Br2 , N2 , Cl2 0

Elements in Group 1 in a compound

HCl, NaCl +1

Elements in Group 2 in a compound

MgF2 , BaO, Ca3N2 +2

OXYGEN in a compound H2O, MnNO3 -2

Aluminum in a compound AlCl3 +3

Note! 1. Nonmetals in groups 15-17 are not listed. 2. Except for OXYGEN, nonmetal charges are variable in Polyatomic ions.


Practice: Assign oxidation numbers to ALL of the elements in each of the compounds or ions below. Start with what is fixed. The sum of the oxidation numbers in the formula should equal the overall charge.

FeO MgSO3 [SO3]-2

AlF3 H2SO4 [Cr2O7]-2

H3PO3 HCl KNO3

Practice: Complete the following steps for each problem.

1. Identify the reaction type. 2. Predict products. 3. Balance the reaction. 4. Show oxidation numbers of all elements. 5. Indicate whether reaction is redox. 6. Place [Ox] above element in reactant that is oxidized and [Red] above element in reactant that is oxidized. The first problem is done for you.

Type of Reaction REDOX?

(S, D, C, SR) (Y/N)

1. __SR____ _2_ Li(s) + ____ SnCl2 (aq) → Sn(s) + 2 LiCl (aq) ___Y__

2. ______ ___ K(s) + ___ O2(g) → _____

3. _______ ____ Cl2(g) + ____ CuI2 (aq) → _____

5. ______ ____ C3H8(g) + _____ O2(g) → _____

6. ______ ____ Fr2O (s) → _____

-2 +2

[Ox]

0

[Red]

0 +1 -1 +2 -1

Unit 8 Notes of 36


8.6 DOUBLE REPLACEMENT REACTIONS: PRECIPITATION & ACID-BASE

A DOUBLE-REPLACEMENT reaction is a reaction in which two ionic compounds in solution swap partners and

forms 2 new ionic compounds.

The cation from one compound joins the anion from the other and vice versa.

There are 2 Types: Precipitation Reactions and Acid-Base Reactions

1. PRECIPITATION REACTIONS

A insoluble (solid!) product, or PRECIPITATE, MUST FORM for a reaction to occur. (see below)

Q: How do we know IF a precipitate will form?

A: We use the Solubility table (page 15). For a reaction to occur, at least one product must be insoluble, which

is called a precipitate.

PREDICT the PRODUCTS of a PRECIPITATION Reaction

1) Write the “swapped” combination of ions as products.

2) Check the solubility table for insoluble products.

3) If all are soluble, no reaction will occur. Write NR on the product side of the reaction.

4) If at least one product is INSOLUBLE, the reaction will occur.

5) Criss-Cross to create the new compounds.

a. Soluble products are aqueous (aq)

b. Insoluble products are solid (s)

Example – predict products and balance

1. __1_SrBr2 (aq) + _2_AgNO3 (aq) Sr(NO3)2 (aq) + 2 AgBr (s)

2. _1_BaCl2 (aq) + _1_Li2CO3 (aq) BaCO3 (s) + 2 LiCl (aq)


1. ___Al2(SO4)3 (aq) + __Ca(OH)2 (aq)

2. ___CaI2 (aq) + ____K3PO4 (aq)

AB + XY -> AY + XB DOUBLE REPLACEMENT REACTION

Unit 8 Notes of 36

2. ACID-BASE REACTIONS

A special type of double replacement reaction in which an acid and base combine. There IS NO precipitate!

The reactants are: an acid – starts with H and… A base – ends with OH

The products are: a salt (ionic compound) and…H2O

When writing the ionic compound, you must be sure to use correct subscripts to balance negative and

positive charges (criss cross)!

Example – predict products and balance

____ HCl (aq) +____ NaOH (aq) NaCl (aq) + H2O


_____ HNO3 (aq) +____ Ba(OH)2 (aq)

_____ HCl (aq) + _____ NaOH (aq)

H-Y + X-OH -> XY + H2O ACID-BASE REACTION


Extra Credit - Balancing Challenge: Balance the following reactions

13. ___(NH4)2CO3 ___NH3 +___CO2 + ___H2O

14. ___HNO3 + ___HI ___NO3 +___I2 + ___H2

15. ___KMnO4 + ___HCl ___MnCl2 +___Cl2 + ___H2O +___KCl

16. ___NH3 +___O2 ___NO +___H2O

17. ___KIO4 + ___KI + ___HCl ___KCl + ___I2 +___H2O

18. ___ Sb + ___HNO3 ___Sb2O5 + ___NO + ___H2O

19. ___Fe2(SO4)3 + ___KSCN ___K3Fe(SCN)6 + ___K2SO4

20. ___FeS2 + ___O2 ___Fe2O3 + ___SO2

21. ___Li+ ___N2 ___Li3N

22. ___C8H18 + ___O2 ___CO2 + ___H2O

Unit 8 Notes of 36

Name Ion Name Ion

acetate C2H3O2–1 or CH3COO–1 hypochlorite ClO–1

ammonium NH4+1 nitrate NO3

–1

carbonate CO3-2 nitrite NO2

–1

chlorate ClO3–1 perchlorate ClO4

–1

chlorite ClO2–1 permanganate MnO4

–1

chromate CrO4-2 phosphate PO4

-3

cyanide CN–1 phosphite PO3-3

dichromate Cr2O7-2 silicate SiO3

-2

hydrogen carbonate HCO3–1 sulfate SO4

-2

hydroxide OH–1 sulfite SO3-2

20 Common Polyatomic Ions

UNIT 8 Chemical Reactions Practice Problems 8... · UNIT 8 – Chemical Reactions Practice Problems...

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