Reactions in Aqueous SolutionChapter 4

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Big Ideas from 4.1-4.2Do substances dissolved in water exist as ions,

molecules, or a mixture of the two?

When do precipitates form when two solutions are mixed?

Tuesday, March 22 Do Now1. Notecard check

2. Questions about the terms

3. A 0.1 M solution of acetic acid (CH3COOH) causes the lightbulb in the apparatus of Figure 4.2 to glow about as brightly as a 0.001 M solution of HBr. How do you account for this fact?

4.1

A ___Solution_______ is a homogenous mixture of 2 or more substances

The __Solute________ is(are) the substance(s) present in the smaller amount(s)

The __Solvent_____ is the substance present in the larger amount

Solution Solvent Solute(s)

Soft drink (l)

Air (g)

Soft Solder (s)

H2O

N2

Pb

Sugar, CO2

O2, Ar, CH4

Sn

An _electrolyte__________ is a substance that, when dissolved in water, results in a solution that can conduct electricity.A __nonelectrolyte___________ is a substance that, when dissolved, results in a solution that does not conduct electricity.

_nonelectrolyte__ _weak electrolyte_ __strong electrolyte_4.1

Strong Electrolyte – __100__% dissociation

NaCl (s) Na+ (aq) + Cl- (aq)H2O

Weak Electrolyte – _chemical equilibrium_____

CH3COOH CH3COO- (aq) + H+ (aq)

Conduct electricity in solution?

_cations__ (+) and _anions___(-)

4.1

_solvation_____ is the process in which an ion is surrounded by water molecules arranged in a specific manner.

H2O

__Glucose______ does not conduct electricity

No cations (+) and anions (-) in solution

4.1

C6H12O6 (s) C6H12O6 (aq)H2O

Strong Electrolytes

Weak Electrolytes Nonelectrolytes

HCl CH3COOH (NH2)2CO

HNO3 HF CH3OH

HClO4 HNO2 C2H5OH

NaOH H2O C12H22O11

Ionic Compounds Weak Acids Covalent Molecules

Practice Problems

• Pg 156, 4.11 – 4.17

Check for Understanding

• What dissolved species are present in a solution of a) KCN, b) NaClO4?

• Which solute will cause a lightbulb to glow more brightly, CH3OH or MgBr2?

Wednesday March 23 Do Now

• What dissolved species are present in a solution of AgNO3? Of Al2(SO4)3?

• Goal for today: I can write molecular equations, complete ionic equations, and net ionic equations.

• I can predict whether or not a precipitate will form in solution.

Notecard Notes

• Molecular Compounds dissolved in water– HCl

• Chemical Equilibrium – going between ions and original substance (HCl not an example)

Precipitation Reactions

__Precipitate_–insoluble solid that separates from solution

_Molecular Equation_____

_Complete Ionic Equation_______

_Net Ionic Equation_______

Pb2+ + 2NO3- + 2Na+ + 2I- PbI2 (s) + 2Na+ + 2NO3

-

Na+ and NO3- are _spectator_____ ions

PbI2

Pb(NO3)2 (aq) + 2NaI (aq) PbI2 (s) + 2NaNO3 (aq)

precipitate

Pb2+ + 2I- PbI2 (s)

4.2

Writing Net Ionic Equations

1. Write the balanced molecular equation.

2. Write the ionic equation showing the strong electrolytes

3. Determine precipitate from solubility rules

4. Cancel the spectator ions on both sides of the ionic equation

AgNO3 (aq) + NaCl (aq) AgCl (s) + NaNO3 (aq)

4.2

Write the net ionic equation for the reaction of silver nitrate with sodium chloride.

Solubility Rules for Common Ionic CompoundsIn water at 250C

4.2

Memorize!

1.All compounds containing alkali metal cations and the ammonium ion (NH4

+1) are soluble. 2.All compounds containing NO3

-, ClO4- (perchlorate), ClO3

-

(chlorate), and C2H3O2- (acetate) anions are soluble.

3.All chlorides, bromides, and iodides are soluble except those containing Ag+, Pb2+, or Hg2+.

4.All sulfates (SO4-2) are soluble except those containing Hg2+, Pb2+,

Sr2+, Ca2+, or Ba2+.

5.All hydroxides (OH-1) are insoluble except compounds of the alkali metals, Ca2+,  Sr2+,and Ba2+.

6.All compounds containing PO43-(phosphate), S2-(sulfide), CO3

2-

(carbonate), and SO32- (sulfite) ions are insoluble except those that

also contain alkali metals or NH4+.

Predict• Write out the net ionic equation for the

reaction between AgNO3 and KI. Will a precipitate form?

• Write out the net ionic equation for the reaction between Ca(OH)2 and SrCl2. Will a precipitate form?

Practice Problems

• Pg 157 4.20, 4.21, 4.23, 4.25, 4.26, 4.28

Thursday, March 24th Do Now • Using the following reactants, write out the

net ionic equation:

Sr(NO3)2(aq) + H2SO4(aq)

Goals: I can define and identify substances as acids or bases.

Acids

Have a sour taste. Vinegar owes its taste to acetic acid. Citrus fruits contain citric acid.

React with certain metals to produce hydrogen gas.

React with carbonates and bicarbonates to produce carbon dioxide gas

Have a bitter taste.

Feel slippery. Many soaps contain bases.

Bases

4.3

Arrhenius_ acid is a substance that produces H+ (H3O+) in water

_ Arrhenius __ base is a substance that produces OH- in water

4.3

A _Bronsted____ acid is a proton donor

A _Bronsted____ base is a proton acceptor

acidbase acid base

4.3

A _Bronsted_ acid must contain at least one ionizable proton!

Monoprotic___ acids

HCl H+ + Cl-

HNO3 H+ + NO3-

CH3COOH H+ + CH3COO-

Strong electrolyte, strong acid

Strong electrolyte, strong acid

Weak electrolyte, weak acid

_Diprotic____ acidsH2SO4 H+ + HSO4

-

HSO4- H+ + SO4

2-

Strong electrolyte, strong acid

Weak electrolyte, weak acid

__Triprotic___ acidsH3PO4 H+ + H2PO4

-

H2PO4- H+ + HPO4

2-

HPO42- H+ + PO4

3-

Weak electrolyte, weak acid

Weak electrolyte, weak acid

Weak electrolyte, weak acid

4.3

_Neutralization____ Reaction

acid + base _water__ + __salt__ + _energy_

All _salts/neutralized solutions are strong electrolytes.

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

H+ + Cl- + Na+ + OH- Na+ + Cl- + H2O

H+ + OH- H2O

4.3

Practice Problems

• Pg 157 4.20, 4.21, 4.23, 4.25, 4.26, 4.28

• Problem Set #1 due tomorrow!!!!

• Solubility Rules Quiz on Monday. 10 pts extra credit on the quiz for a catchy way of remembering the rules.

Oxidation-Reduction Reactions(electron transfer reactions)

2Mg (s) + O2 (g) 2MgO (s)

2Mg 2Mg2+ + 4e-

O2 + 4e- 2O2-

________ half-reaction (lose e-)

________ half-reaction (gain e-)

2Mg + O2 + 4e- 2Mg2+ + 2O2- + 4e-

2Mg + O2 2MgO

4.4

Zn (s) + CuSO4 (aq) ZnSO4 (aq) + Cu (s)

Zn is ________Zn Zn2+ + 2e-

Cu2+ is _______Cu2+ + 2e- Cu

Zn is the ________ agent

Cu2+ is the _______ agent

4.4

4.4

Copper wire reacts with silver nitrate to form silver metal.What is the oxidizing agent in the reaction?

Cu (s) + 2AgNO3 (aq) Cu(NO3)2 (aq) + Ag (s)

Cu Cu2+ + 2e-

Ag+ + 1e- Ag Ag+ is ________ Ag+ is the _____________

Oxidation number

The charge the atom would have in a molecule (or anionic compound) if electrons were completely transferred.

1. Free elements (uncombined state) have an oxidation number of zero.

Na, Be, K, Pb, H2, O2, P4 = 0

2. In monatomic ions, the oxidation number is equal to the charge on the ion.

Li+, Li = +1; Fe3+, Fe = +3; O2-, O = -2

3. The oxidation number of oxygen is usually –2. In H2O2

and O22- it is –1.

4.4

4. The oxidation number of hydrogen is +1 except when it is bonded to metals in binary compounds. In these cases, its oxidation number is –1.

6. The sum of the oxidation numbers of all the atoms in a molecule or ion is equal to the charge on the molecule or ion.

5. Group IA metals are +1, IIA metals are +2 and fluorine is always –1.

HCO3-

O = H =

3x-2 + 1 + ? = -1

C =

Oxidation numbers of all the atoms in HCO3

- ?

4.4

NaIO3

Na = O =

3x-2 + 1 + ? = 0

I =

IF7

F =

7x-1 + ? = 0

I =

K2Cr2O7

O = K =

7x-2 + 2x+1 + 2x? = 0

Cr =

Oxidation numbers of all the atoms in the following ?

4.4

Types of Oxidation-Reduction Reactions

Reaction

A + B C

S + O2 SO2

Reaction

2KClO3 2KCl + 3O2

C A + B

0 0 +4 -2

+1 +5 -2 +1 -1 0

4.4

Reaction

A + BC AC + B

Sr + 2H2O Sr(OH)2 + H2

TiCl4 + 2Mg Ti + 2MgCl2

Cl2 + 2KBr 2KCl + Br2

Hydrogen Displacement

Metal Displacement

Halogen Displacement

Types of Oxidation-Reduction Reactions

4.4

0 +1 +2 0

0+4 0 +2

0 -1 -1 0

The Activity Series for Metals

M + BC AC + B

Displacement Reaction

M is metalBC is acid or H2O

B is H2

Ca + 2H2O Ca(OH)2 + H2

Pb + 2H2O Pb(OH)2 + H2

4.4

Reaction

Cl2 + 2OH- ClO- + Cl- + H2O

Element is simultaneously oxidized and reduced.

Types of Oxidation-Reduction Reactions

Chlorine Chemistry

0 +1 -1

4.4

Ca2+ + CO32- CaCO3

NH3 + H+ NH4+

Zn + 2HCl ZnCl2 + H2

Ca + F2 CaF2

__________________

__________________

__________________

__________________

Classify the following reactions.

4.4

Solution Stoichiometry

The ________________ of a solution is the amount of solute present in a given quantity of solvent or solution.

M = ____________ =moles of solute

liters of solution

4.5

Solution Stoichiometry

What mass of KI is required to make 500 mL ofa 2.80 M KI solution?

volume KI moles KI grams KIM KI M KI

500 mL = _____ g KI166 g KI

1 mol KIx

2.8 mol KI

1 L solnx

1 L

1000 mLx

4.5

4.5

________________ is the procedure of preparing a less concentrated solution

from a more concentrated solution.

Dilution

Add Solvent

Moles of solutebefore dilution (i)

Moles of soluteafter dilution (f)=

MiVi MfVf=4.5

How would you prepare 60.0 mL of 0.200 MHNO3 from a stock solution of 4.00 M HNO3?

MiVi = MfVf

Mi = 4.00 Mf = 0.200 Vf = 0.06 L Vi = ? L

4.5

Vi =MfVf

Mi

= =

Gravimetric Analysis

4.6

1. Dissolve unknown substance in water

2. React unknown with known substance to form a precipitate

3. Filter and dry precipitate

4. Weigh precipitate

5. Use chemical formula and mass of precipitate to determine amount of unknown ion

___________________In a _____________________ a solution of accurately known concentration is added gradually added to another solution of unknown concentration until the chemical reaction between the two solutions is complete.

________________ – the point at which the reaction is complete

_______________ – substance that changes color at (or near) the equivalence point

Slowly add baseto unknown acid

UNTIL

The indicatorchanges color

(pink) 4.7

What volume of a 1.420 M NaOH solution is required to titrate 25.00 mL of a 4.50 M H2SO4 solution?

4.7

BALANCE THE CHEMICAL EQUATION!

volume acid moles acid moles base volume base

H2SO4 + NaOH H2O + Na2SO4

M

acid

rx

coef.

M

base

What volume of a 1.420 M NaOH solution isRequired to titrate 25.00 mL of a 4.50 M H2SO4 solution?

4.7

BALANCE THE CHEMICAL EQUATION!

volume acid moles acid moles base volume base

H2SO4 + 2NaOH 2H2O + Na2SO4

4.50 mol H2SO4

1000 mL solnx

2 mol NaOH

1 mol H2SO4

x1000 ml soln

1.420 mol NaOHx25 mL = _____ mL

M

acid

rx

coef.

M

base

(4.72 p.120) What volume of a 0.500 M KOH solution is required to titrate 10.0 mL of a 0.20 M H2SO4 solution?

4.7

volume acid moles acid moles base volume base

H2SO4 + KOH H2O + K2SO4

___ mol H2SO4

____ mL solnx

__ mol KOH

__ mol H2SO4

x____ ml soln

____ mol KOHx10.0 mL = ___ mL

M

acid

rx

coef.

M

base

(4.72 p.120) What volume of a 0.500 M KOH solution is required to titrate 10.00 mL of a 0.20 M H2SO4 solution?

4.7

volume acid moles acid moles base volume base

H2SO4 + 2KOH 2H2O + Na2SO4

0.20 mol H2SO4

1000 mL solnx

2 mol KOH

1 mol H2SO4

x1000 ml soln

0.500 mol KOHx10.0 mL = _____ mL

M

acid

rx

coef.

M

base