Chemical Reactions Slide 3 / 142 Table of Contents: Chemical - - PDF document
Slide 1 / 142 Slide 2 / 142 Chemical Reactions Slide 3 / 142 Table of Contents: Chemical Reactions Chemical Equations Click on the topic to go to that section Balancing Equations Types of Chemical Reactions Precipitation Reactions
· Balancing Equations
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· Types of Chemical Reactions · Oxidation-Reduction Reactions · Chemical Equations · Net Ionic Equations · Types of Oxidation-Reduction Reactions · Acid-Base Reactions · Precipitation Reactions · Identifying Reaction Types: Summary
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Chemical equations are concise representations of chemical reactions.
The formulas of the reactants (on the left) are connected by an arrow with the formulas of the products (on the right). To write a word equation, write the names of the reactants to the left of the arrow separated by plus signs. Write the names of the products to the right of the arrow, also separated by plus signs. Reactant + Reactant Product + Product
A skeleton equation is a chemical equation that does not indicate the relative amounts of the reactants and products. Write the formulas of the reactants to the left of the yields sign (arrow) and the formulas of the products to the right. Here is the equation for rusting: Metallic Iron reacts with oxygen in the air to produce iron (III) oxide (rust). Iron( metal) + Oxygen ( gas) ⇒ iron (III) oxide ( solid) (word equation) Fe + O2 # Fe2O3 ( skeleton /chemical equation)
When ignited, methane gas reacts with oxygen gas to produce carbon dioxide and steam. CH4 gas O2 gas CO2 gas
H2O gas
This "skeleton" equation is not balanced: CH4 (g) + O2 (g) H2O (g) + CO2 (g)
answer
A solids B
liquids
C gases D dissolved in water (aqueous) E
cannot be determined F I don't know how to answer this.
answer
Solid potasium chlorate decomposes in air to produce solid potassium chloride and oxygen gas. The word equation is: potasium chlorate (s) --> potassium chloride (s) + oxygen (g) The unbalanced "skeleton" equation is: KClO3(s) KCl(s) + O2(g)
Write the word equation, then the skeleton equation Aluminum sulfate reacts with calcium chloride to produce calcium sulfate and aluminum chloride Al2(SO4)3 + CaCl2 --> Ca(SO4) + AlCl3
Aluminum sulfate + calcium chloride --> calcium sulfate + aluminum chloride
Slide for Word equation
“We may lay it down as an incontestable axiom that, in all the operations of art and nature, nothing is created; an equal amount of matter exists both before and after the experiment. Upon this principle, the whole art of performing chemical experiments depends.”
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To write a balanced chemical equation, first write the skeleton
This is a balanced equation for making a bicycle. The numbers are called coefficients—small whole numbers that are placed in front of the formulas in an equation in order to balance it.
CH4 (g) + 2 O2 (g) # CO2 (g) + 2 H2O (g) Reactants appear on the left side of the equation. Products appear on the right side of the equation. The states of the reactants and products are written in parentheses to the right of each compound.
1C 4H 4 O 1C 2 O 2 O 4H
Coefficients are inserted to balance the equation.
CH4 (g) + 2 O2 (g) # CO2 (g) + 2 H2O (g)
1C 4H 4 O 1C 2 O 2 O 4H
Subscripts tell the number of atoms of each element in a molecule. Coefficients tell the number of representative particles (atoms, molecules, or formula units).
for calcium nitrate.)
I don't know how to answer this.
answer
answer
chlorine + sodium bromide # bromine + sodium chloride
Write a balanced chemical equation for this reaction. First write a skeleton equation Cl2 + NaBr # # Br2 + NaCl
Then, count up the number of each type of element on each side of the reaction Cl2 + NaBr # # Br2 + NaCl
Cl: 2 Cl: 1 Na: 1 Na: 1 Br: 1 Br: 2
Next, identify one element that is not balanced. It is best to start with an easy element. The fewer places an element appears on both sides of a reaction, the easier it will be to balance. Cl2 + NaBr # # Br2 + NaCl
Cl: 2 Cl: 1 Na: 1 Na: 1 Br: 1 Br: 2
Identify the side that needs more of that particular element. Cl2 + NaBr # # Br2 + NaCl
Cl: 2 Cl: 1 Na: 1 Na: 1 Br: 1 Br: 2
Determine which molecule or element will be getting the
products side, we will have to add a coefficent to the NaCl, since that is the only product containing chlorine.
Cl: 2 Na: 1 Br: 1
Cl2 + NaBr # # Br2 + NaCl
Cl: 2 Cl: 1 Na: 1 Na: 1 Br: 1 Br: 2
To figure out what the coefficient should be, simply take the amount of that specific element you need from the molecule, and divide by the amount of the element you have in the molecule. Cl2 + NaBr # # Br2 + __NaCl
Need Have = 2 1 =
Cl: 2 Na: 1 Br: 1
Cl: 2 Cl: 1 Na: 1 Na: 1 Br: 1 Br: 2
If this is not a whole number, simply multiply ALL the substances in the reaction by some whole number to make the coefficients whole numbers.
Now, just reevaluate the amount of each element on the table
Cl: 2 Na: 1 Br: 1
Cl2 + NaBr # # Br2 + 2NaCl
Cl: 2 Cl: 1 2 Na: 1 Na: 1 2 Br: 1 Br: 2
Continue with these steps until all the elements are balanced. When all the elements exist in equal amounts on both sides of the equation, you have a balanced chemical equation.
Cl: 2 Na: 1 Br: 1
Cl2 + 2NaBr # # Br2 + 2NaCl
Cl: 2 Cl: 1 2 Na: 1 2 Na: 1 2 Br: 1 2 Br: 2
SPECIAL NOTE: Make sure that when you are calculating your coefficents you are only looking at the amounts needed/had by individual elements or molecules
Cl: 2 Na: 1 Br: 1
CH3OH + O2 # # CO2+ 2H2O
C: 1 C: 1 H: 4 H: 2 4 O: 1+2=3 O: 2+1=3 2+2=4
SPECIAL NOTE: Here is the incorrect way to evaluate the coefficent in this case
Cl: 2 Na: 1 Br: 1
CH3OH + O2 # # CO2+ 2H2O
C: 1 C: 1 H: 4 H: 2 4 O: 1+2=3 O: 2+1=3 2+2=4
Need Have = 4 3 = WRONG!!!
SPECIAL NOTE: Here is the correct way to evaluate the coefficent in this case
Cl: 2 Na: 1 Br: 1
CH3OH + O2 # # CO2+ 2H2O
C: 1 C: 1 H: 4 H: 2 4 O: 1+2=3 O: 2+1=3 2+2=4
Need Have = 4 - 1 2
Because we already have 1 Oxygen from CH3OH, we only need 3 Oxygen from O2 Because O2 only has 2 Oxygen, the denominator must be 2.
3 2
SPECIAL NOTE: Remember to make sure you get rid
2CH3OH + 2x O2 # # 2CO2+ 2x2H2O
3 2
Cl: 2 Na: 1 Br: 1
C: 1 2 C: 1 2 H: 4 8 H: 2 4 8 O: 1+2=3 2+6=8 O: 2+1=3 2+2=4 4+4=8
If you follow these steps, you'll be able to balance any type of reaction. 2CH3OH + 3O2 # # 2CO2+ 4H2O
Cl: 2 Na: 1 Br: 1
C: 1 2 C: 1 2 H: 4 8 H: 2 4 8 O: 1+2=3 2+6=8 O: 2+1=3 2+2=4 4+4=8
Na + O2 # Na2O
answer
HgO # Hg + O2
answer
Al + ZnCl2 # Zn + AlCl3
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NaCl + CaI2 # NaI + CaCl2
answer
NH3 + O2 # NO2 + H2O
answer
Al(NO3)3 + Na2S # Al2S3 + NaNO3
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Precipitation: formation of insoluble product out of aqueous solutions Oxidation/Reduction: exchange of electrons between atoms/ions Acid/Base: reaction between acids and bases Most reactions can be classified as one of the following:
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The giant clam's shell is made from the precipitation of CaCO3
Precipitation reactions involve the reaction of water soluble ionic compounds to form a water insoluble product called a precipitate: AgNO3(aq) + HCl(aq) --> AgCl(s) + HNO3(aq)
AgCl precipitate
One must know which ionic compounds are water soluble and which are not. It is the insoluble ones that form precipitates! Some general rules apply:
ALWAYS SOLUBLE
SOMETIMES SOLUBLE INSOLUBLE (unless paired with a soluble ion)
NH4+, C2H3O2-, ClO3-, Group 1 A metal ions, NO3- Cl-,Br-, I- except when combined with Ag+, Hg+, and Pb2+ SO42- except when combined with Ag+, Hg+, Pb2+, Ca2+, Sr2+, Ba2+ CO32-, PO43-, OH-, S2-, F-, O2-
A Na2CO3 B NH4NO3 C AgNO3 D Mg(OH)2 E KCl
answer
A CaSO4 B PbF2 C PbI2 D Cu(OH)2 E CuSO4
answer
A solubility chart provides more exact information as to the individual solubilities of various ionic substances.
Note that S on this chart means that the compound is soluble. When you write a chemical equation, it will be (aq) aqueous. Insoluble compounds are shown with the letter I. When you write a chemical equation, it will be (s) solid.
Precipitation reactions are often called "double replacement" or "double displacement" reactions because it appears as if the ions switch places with each other. NaCl(aq) + AgNO3(aq)
AgCl(s) + NaNO3(aq)
Na+ and Ag+ switch places
Pb(NO3)2(aq) + 2 KI(aq) # PbI2(s) + 2 KNO3(aq) AgNO3(aq) + KCl(aq) # AgCl(s) + KNO3(aq)
The formation of an insoluble precipitate is the driving force of these reactions
A precipitation reaction will NOT occur if both products are water soluble.... 2NaNO3(aq) + MgCl2(aq) --> 2NaCl(aq) + Mg(NO3)2(aq)
Since both products are soluble, no reaction occurs
Predict the products of this reaction: potassium phosphate + magnesium chloride --> K3PO4 (aq) + MgCl2 (aq) --> KCl + Mg3(PO4)2
Now, put in the phases of the products and balance the equation.
2K3PO4 (aq) + 3MgCl2 (aq) --> 6KCl(aq) + Mg3(PO4)2(s)
Predict the products of this reaction: calcium fluoride + sodium sulfate --> CaF2 (aq) + Na2SO4 (aq) --> NaF + Ca(SO4)(s)
Now, put in the phases of the products and balance the equation.
CaF2 (aq) + Na2SO4 (aq) --> 2NaF (aq) + Ca(SO4)(s)
A Mg3(PO4)2(aq) + NaC2H3O2(aq) B Mg3(PO4)2(s) + NaC2H3O2(aq) C Mg3(PO4)2(aq) + NaC2H3O2(s) D Mg3(PO4)2(s) + NaC2H3O2(s) E Mg3(PO4)2(s) + NaC2H3O2(s)
answer
A
silver potassium(aq)
potassium carbonate(aq)
nitrate carbonate(aq)
potassium nitrate(aq)
potassium carbonate(s)
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In order to better represent what is actually happening in a precipitation reaction, two things must be accounted for:
separated when dissolved in water. For example....
NaCl(aq) + AgNO3(aq) --> AgCl(s) + NaNO3(aq) can be written in ionic form as Na+(aq) + Cl-(aq) + Ag+(aq) + NO3(aq)- --> AgCl(s) + Na+(aq) + NO3-(aq)
In order to better represent what is actually happening in a precipitation reaction, two things must be accounted for:
formation of the precipitate) are called spectator ions and can be eliminated. Reactions written this way are called Net Ionic Equations.
Ag+(aq) + Cl-(aq) --> AgCl(s)
The complete ionic equation shows all aqueous substances (i.e. strong acids, strong bases, and soluble ionic compounds) dissociated into their ions. For example:
NaCl (aq) would be written as Na+ (aq) + Cl- (aq)
Note: all ionic compound if soluble in water will readily dissociate into the corresponding (+) and (-) ions.
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However, when all the aqueous species are dissociated into their respective ions, it becomes:
Ag+ (aq) + NO3- (aq) + K+ (aq) + Cl- (aq) --->AgCl (s) + K+ (aq) + NO3- (aq)
The equation between silver nitrate and potassium chloride would normally be shown as AgNO3 (aq) + KCl(aq) --->AgCl (s) + KNO3 (aq) This is called the complete ionic equation. Note that the insoluble product does not dissociate.
Ag (aq) + NO3-(aq) + K+(aq) + Cl-(aq) --->AgCl (s) + K+(aq) + NO3- (aq)
As this example shows, certain ions are present both before and after the reaction. Because they play no significant role in the reaction, they are known as "spectator ions." A spectator ion is an ion that appears on both sides of an equation and is not directly involved in the reaction.
The net ionic equation is an equation for a reaction in solution that shows only those particles that are directly involved in the chemical change. To form the net ionic equation, cross out anything that does not change from the left side of the equation to the right. In other words, cancel out the spectator ions.
Ag (aq) + NO3-(aq) + K+(aq) + Cl-(aq) --->AgCl (s) + K+(aq) + NO3- (aq)
After cancelling out the spectator ions, the only things left in the equation are those things that change, or react, during the course of the reaction.
Ag+(aq) + NO3-(aq) + K+(aq) + Cl-(aq) AgCl (s) + K+(aq) + NO3-(aq) This is called the net ionic equation.
Write a balanced molecular equation.
Write a balanced molecular equation. Dissociate any reactants or products that are aqueous. All solids, liquids, and gases stay intact and do not dissociate.
Write a balanced molecular equation. Dissociate any reactants or products that are aqueous. All solids, liquids, and gases stay intact and do not dissociate. Cross out anything that remains unchanged from the left side to the right side of the equation.
Write a balanced molecular equation. Dissociate any reactants or products that are aqueous. All solids, liquids, and gases stay intact and do not dissociate. Cross out anything that remains unchanged from the left side to the right side of the equation. Write the net ionic equation with the species that remain.
In all cases (involving double replacement), it will be the reaction between the ions that produces the insoluble precipitate.
Write a balanced molecular equation.
Pb(NO3)2 (aq)+ 2 KI (aq) --> PbI2 (s)+ 2 KNO3 (aq) Dissociate any reactants or products that are aqueous. Pb2+(aq) + 2NO3-(aq)+ 2K+(aq)+ 2I-(aq)# PbI2 (s)+ 2K+(aq)+ 2NO3-(aq) Cross out anything that remains unchanged from the left side to the right side of the equation. Pb2+(aq) + 2NO3-(aq)+ 2K+(aq)+ 2I-(aq)# PbI2 (s)+ 2K+(aq)+ 2NO3-(aq) Write the net ionic equation with the species that remain. Pb2+(aq) + 2 I-(aq) --> PbI2 (s)
Practice writing the balanced equation, complete ionic equation and net ionic equation for these reactions.
Ca2+ (aq) + CO32- (aq) --> CaCO3 (s)
Slide for Answer
Practice writing the balanced equation, complete ionic equation and net ionic equation for these reactions.
3Ag+ (aq) + PO43- (aq) --> Ag3PO4 (s)
Slide for Answer
A
Na+(aq) + OH-(aq) + Ba2+(aq) + Cl-(aq) -->NaBa(s) + ClOH(aq)
B Ba2+(aq) + 2Cl-(aq) --> BaCl2(s) C Ba2+(aq) + 2OH-(aq) --> Ba(OH)2(s) D Na+(aq) + Cl-(aq) --> NaCl(s) E
Na+(aq) + OH-(aq) + Ba2+(aq) + 2Cl-(aq) -->Ba(OH)2(s) + NaCl(aq)
answer
A NaCl B NH4NO3 C BaI2 D KC2H3O2 E LiClO3
answer
A Pb2+ and I- B NO3- and Na+ C NO3- and I- D Pb2+ and Na+ E Na+ and I-
answer
This is a river in China that became contaminated with Cd2+ ions. Knowing what you know about precipitation reactions, what do you think could be added to remove the Cd2+ ions? Cd ions are often removed by adding hydroxides or sulfides to form precipitates that can be filtered out of the water
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The thermite reaction between iron(III)oxide and Al generates a lot of heat! Recall that Oxidation/Reduction Reactions involve exchange of electrons between atoms/ions
These reactions, often called REDOX reactions, involve a transfer of electrons from one element to another. 4Al(s) + 3O2(g) 2Al2O3
Charge +3 -2
Each Al loses 3 electrons Each O gains 2 electrons
Oxidation element loses electrons Reduction element gains electrons
The electrons lost/gained must be balanced in a REDOX reaction
Each Al loses 3 electrons Each O gains 2 electrons
4Al(s) + 3O2(g) --> 2Al2O3
4 x Al x 3e- lost = 12 e- lost 6 x O x 2e- gained = 12 e- gained
In order to determine if a reaction is an oxidation/reduction reaction and which element got oxidized or reduced, one must be able to track the charges (oxidation states) of elements throughout the reaction.
Oxidation States
Since the charges on both the zinc and hydrogen change, this is definitely a redox reaction.
Substance Oxidation State H2(g) Ca(s) Na+(aq) +1 F-(aq)
All elements in their standard (neutral) state, have an oxidation state of zero. If the element has a charge listed, this is it's
Rule 1: The charges of all the elements in the compound have to add up to the charge of the compound. Example: ZnO The compound is neutral so... Charge of Zn + Charge of O = 0 Example: NO3- The compound has a charge of -1 so... Charge of N + charge of O = -1
If the element is combined with others, the oxidation state will have to be deduced using the periodic table, your knowledge of ionic compounds, and some mathematics. Here are some general guidelines...
Guideline 1: The charges of all the elements in the compound have to add up to the charge of the compound. Guideline 2: Using your periodic table, find the charge on the anion and use this and what you know to be the charge on the whole compound to find the charge on the cation. Typically, the cation is written first and the anion second. Example: ZnO Charges zinc
ZnO ? 2- 2+ + 2- = zinc has a +2 oxidation state!
Another Example: NO3- Charges N Ox3 NO3- ?
+5 +
= -1 Oxidation States: N = +5 O = -2
Another Example: Cr2O72-(aq) Charges Cr x 2 O x 7 Cr2O72- ?
+12 +
= -2 Since Cr x 2 = +12 ... the oxidation state of each Cr must be +6! Oxidation states: Cr = +6 O = -2
Another example: HS- Charges H S HS- ?
+1 +
H = +1, S = -2
Another Example: N2O4 Charges Nx2 Ox4 N2O4 ?
+8 +
= Since Nx2 =8, each N = 4 so.... N = +4, O = -2
A ZnS B Zn C Zn2+ D ZnSO4 E ZnCl2
answer
19 What is the oxidation state of P in the phosphate ion -- PO43-? A 0 B +1 C +3 D +5 E -3
answer
A 0 B -1 C +1 D +3 E +5
answer
For elements containing three elements, find the oxidation states of the first and last from the periodic table and then find the middle element (usually but not always a transition metal). Example: Na2S2O3 Charges Na x2 Sx2 Ox3 Na2S2O3 +1(2)= +2 ?
2 + 4
Since Sx2 = 4, each sulfur will have a charge of just +2 so....Na =+1, S =+2, and O = -2
Example: Mg(OH)2 charges Mg Ox2 Hx2 Mg(OH)2 +2
+1(2)=+2 2 +
+ 2 = All of these charges could be obtained using the periodic table so nothing needed to be figured out! Mg = +2, O = -2, and H = +1
Example: KMnO4 charges K Mn Ox4 KMnO4 +1 ?
1 + 7
= So... K = +1, Mn = +7, and O = -2
A K = +1, Te = +6, O = -2 B K = +2, Te = +4, O = -2 C K = +1, Te = +4, O = -2 D K = +1, Te = +2, O = -2 E K = +1, Te = +8, O = -2
answer
A Na2SO4 B Na2SO3 C Na2S D S8 E SO3
answer
1)Peroxides like Na2O2 and H2O2 Oxygen has an oxidation state of -1 instead of -2 2) Ammonia (NH3) and ammonium (NH4+) Usually the element with the - charge is written second but that is not the case here. N carries a -3 charge in both instances and H carries a +1 charge.
A O2 B Na2O C Li2O2 D H2O E None of these
answer
What are the oxidation states of each element in the following reaction? Fe2+(aq) + MnO4-(aq) + H+ --> H2O + Mn2+ + Fe3+ +2 +7, -2 +1 --> +1, -2 +2 +3 slide for answer
What are the oxidation states of each of the elements in the reaction? 2H2O2 --> 2H2O + O2 +1, -1 +1,-2 *note that H2O2 is a peroxide
Key: Ignore coefficients when you find oxidation states!
slide for answer
24 In the following equation: 2KClO3 --> 2KCl + 3O2
A -2 --> -2 B -6 --> -2 C -6 --> 0 D -2 --> 0 E -1 --> 0
answer
25 In the following equation: 2KClO3 --> 2KCl + 3O2
A -1 --> -1 B 0 --> -1 C +3 --> +5 D + 5 --> -1 E +5 --> 0
answer
To determine which species in a reaction got oxidized or reduced,
Oxidation = Loss of electrons Na --> Na+ + e- 0 --> +1 Notice that an element becomes more + when it gets oxidized. Reduction = Gain of electrons Mg2+ + 2e - --> Mg +2
Notice that an element becomes less + when it gets reduced.
Which element got oxidized and which got reduced in the following reaction? 2KClO3
Find Ox. States +1,+5, -2 +1,-1 0 Oxygen went from -2 --> 0 becoming more + so it must have lost electrons Chlorine went from +5 --> -1 becoming less + so it must have gained electrons reduced
Which of the following elements got oxidized and reduced in the following reaction? 2F-(aq) + Cl2(g) --> 2Cl-(aq) + F2(g)
Flourine went from -1 to 0 becoming more + meaning electrons were lost = oxidation! Chlorine went from 0 to -1 becoming more - meaning electrons were gained = reduction!
Anti-oxidants like carotenoids found in veggies have many electrons to lose so they help reduced the radicals so the molecules in your body don't get harmed!!! So...eat your veggies!!!
carotenoid -----> free radical singlet O ----->
An oxidant is a chemical species that wants to be reduced so it causes something else to get oxidized. Free radical species like singlet oxygen are oxidants and not good for you as they will get electrons from molecules in your body that need them! O + 2e- --> O
A An elements charge going from -3 --> -2 B An elements charge going from -2 -->-3 C An elements charge going from 0 --> +2 D An elements charge going from +1 --> +3 E None of these
answer
A Al3+(aq) --> Al(s) B F2(g) --> 2F-(aq) C Mn7+ --> Mn2+ D Fe2+(aq) --> Fe3+(aq) E O-(aq) --> O2-(aq)
answer
A 2H2O2 -- 2H2O + O2 B 2H2O --> 2H2 + O2 C CH4 + 2O2 --> CO2 + 2H2O D 3Fe + 3O2 --> 2Fe2O3 E None of these
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29 Which of the following is NOT an oxidation/reduction reaction?
A Ca + 2H+ --> Ca2+ + H2 B H2 + Cl2 -->2HCl C 4Al + 3O2 --> 2Al2O3 D CaO + CO2 --> CaCO3 E Mg3N2 --> 3Mg + N2
answer
Chromium metal is used as rust resistant coating over steel as shown
C gets oxidized and releases a lot of energy which is used to generate the potential so electrons will move through the wire and reduce the Cr3+ ions. CH4 + 2O2 --> CO2 + 2H2O
+4
What element do you think gets
burning power plant to provide the energy so chromium can get reduced? Cr3+ + 3e- --> Cr(s) Slide for Answer
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There are essentially four types of Redox reactions:
2Mg(s) + O2(g) --> 2MgO(s)
2LiClO3(s) --> 2LiCl(s) + 3O2(g)
C(s) + O2(g) --> CO2(g) CH4(g) + 2O2(g) --> CO2(g) + 2H2O(g)
Hg2Cl2 → Hg + HgCl2
Examples: · 2 Mg (s) + O2 (g) 2 MgO (s) · N2 (g) + 3 H2 (g) 2 NH3 (g) · C3H6 (g) + Br2 (l) C3H6Br2 (l) Two or more substances react to form
Mg O2 MgO
C AgNO3 + BaSO4 --> Ag2SO4 + Ba(NO3)2
answer
One substance breaks down into two or more substances.
Examples: CaCO3 (s) CaO (s) + CO2 (g) 2 KClO3 (s) # 2 KCl (s) + 3 O2 (g) 2 NaN3 (s) 2 Na (s) + 3 N2 (g) #
2 H2O # O2 + 2 H2
B Na + Cl2 --> NaCl C AgNO3 + BaSO4 --> Ag2SO4 + Ba(NO3)2 D C3H8 + O2 --> H2O + CO2 E Ca2+(aq) + SO4
2-(aq) --> CaSO(s)
answer
Examples: CH4 (g) + 2 O2 (g) CO2 (g) + 2 H2O (g) C3H8 (g) + 5 O2 (g) 3 CO2 (g) + 4 H2O (g)
These are generally rapid reactions that produce a flame. Most often involve hydrocarbons reacting with oxygen in the air. O2 is always one of the reactants.
Note: substances other than hydrocarbons may also undergo combustion: Mg (s) + O2 (g) ---> MgO (s) N2 (g) + 2 O2 (g) ---> 2 NO2 (g) These last two may also be classified as combination reactions.
A H2O --> H2 +O2
C AgNO3 + BaSO4 --> Ag2SO4 + Ba(NO3)2 D C3H8 + O2 --> H2O + CO2 E Ca2+ + SO42- --> CaSO4(s)
answer
Combustion reactions are easily identified by oxygen as a reactant. However, the products of a combustion reaction may vary depending
Complete combustion products are carbon dioxide and water Incomplete combustion products are carbon monoxide and water
The same element gets both oxidized and reduced. Hg2Cl2
+ HgCl2
+2 , -1 Hg gets both oxidized (+1 -->+2) and reduced (+1 -->0)
Is the following a disproportionation reaction and if so, what element is getting both oxidized and reduced?
Cl2 + 6 OH− → 5 Cl− + ClO3− + 3 H2O
Oxid.States 0
+5,-2 +1,-2
It is! Cl is the element that gets both oxidized and reduced
A CO → C + CO2 B CaCO3 --> CaO + CO2 C H2O --> H2 + O2 D H2 + F2 --> 2HF E none of these
answer
34 Which element gets both oxidized and reduced in the
A Na B Cl C O D H E This is NOT a disproportionation reaction
answer
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Soda pop contains two common weak acids: phosphoric acid (H3PO4) and carbonic acid (H2CO3)
Acid = H+ ion donor Base = H+ acceptor H+ acceptor H+ donor
Acid = electron pair acceptor Base = electron pair donor ** unless otherwise noted, we will be using the bronsted/lowry definition of acids and bases throughout the rest of the presentation.
Bronsted/Lowry Acid/Base reactions involve the transfer of H+ ions from one an acid (H+ donor) to a base (H+ acceptor)
Example: HC2H3O2(aq) + CO32-(aq) --> HCO3-(aq) + C2H3O2-(aq) HC2H3O2(aq) gave away it's H+ = acid CO32-(aq) accepted an H+ = base
Identify the acid and base in the following reaction: CN- + H2O --> HCN + OH- CN- accepted an H+ so it is a base H2O donated an H+ so it is an acid
Identify the acid and base in the following reaction: HCO3- + HF --> F- + H2CO3 HCO3- accepted an H+ so it was a base HF donated an H+ so it was an acid
move for answer
Neutralization reactions are a special type of acid/base reaction in which an acid and base react to produce water. Example: HF + OH- --> H2O + F-
A H+ + CN- --> HCN B HNO2 + OH- --> H2O + NO2- C HCN + NH3 --> NH4+ + CN- D HCO3- + H2O --> CO32- + H3O+ E none of these
answer
The classic childhood reaction of vinegar (HC2H3O2) and baking soda (HCO3-) is an acid/base reaction. Which molecule is the conjugate base of acetic acid (HC2H3O2)? C2H3O2-
answer
HC2H3O2(aq) + HCO3-(aq) --> C2H3O2-(aq) + CO2(g) + H2O(l)
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One can determine the type of chemical reaction by following some basic guidelines.... 1) Are you forming a precipitate? Look for the formation of an insoluble solid 2) Check to see if H+ ions are being transferred? If so, you've got an acid/base reaction 3) Check oxidation states If they change, you've got an oxidation/reduction reaction
What kind of reaction is the following? C4H8(s) + O2(g) --> CO2(g) + H2O(g) 1) Is there a precipitate? 2) Is there a transfer of H+ ions? 3) Check oxidation states....
What kind of reaction is the following? C4H8(s) + O2(g) --> CO2(g) + H2O(g) 1) Is there a precipitate? No - So... not a precipitation reaction 2) Is there a transfer of H+ ions? No - So...not an acid/base reaction 3) Check oxidation states.... C4H8(s) + O2(g) --> CO2(g) + H2O(g)
+4,-2 +1,-2 Carbon changes from -2 --> +4 and Oxygen changes from 0 -->-2. Oxidation states are definitely changing = REDOX!!!
A CH3COOH + NH3 --> NH4+ + CH3COO- B AlCl3(s) --> Al3+(aq) + 3Cl-(aq) C 2Ag+(aq) + Cu(s) --> Cu2+(aq) + 2Ag(s) D H+(aq) + OH-(aq) --> H2O(l) E Zn2+(aq) + CO32-(aq) --> ZnCO3(s)
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What type of chemical reaction is the following? Mg2+(aq) + 2OH-(aq) --> Mg(OH)2(s)
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A H2O + CN- --> OH- + HCN B 2CuO -->2Cu + O2 C NH3 + HSO4- --> NH4+ + SO42- D H+ + OH- --> H2O E All of these are acid/base reactions
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