Chapter 2: Antacids. Antacids Mixture Are a Compounds Chemical Formulas Chemical Formulas Collision Theory Acids & Bases Chemical Reactions Of different.

Chapter 2: Antacids

Antacids

MixtureMixture

Are a

CompoundsCompounds

ChemicalFormulas

ChemicalFormulas

Collision Theory

Collision Theory

Acids & BasesAcids & Bases

Chemical ReactionsChemical Reactions

Of differentSymbolizedwith

Some are

Balanced Chemical Equations

Balanced Chemical Equations

undergo

Symbolizedwith

Used in

Speed governed by

Antacids versus Acid Inhibitors

Acid InhibitorsAntacids

Neutralizes the acid currently in your system

Controls the amount of acid your body produces

There are two types of medicines you can use

Work quickly but your body will make more acid again

Long-term solution, but needs to build up in your system to be

most effective

Alka-Seltzer ®, Rolaids ®, Tums ®, Malox ®, Mylanta ®

Tagamat ®, Zantac ®, Pepcid AC ®

Is it fair when a commercial compares the fast action of an antacid to an acid inhibitor that takes up to 7 days to build up?

Section 2.1—Types of Matter

Matter can be classified

Matter

Pure Substances

Mixtures

Element CompoundHomogeneous

(Solutions)Heterogeneous

Matter

• Anything that has mass and takes up space• Anything made from atoms• Examples:

– Molecules– Cells– People– Air– Water

Pure Substances versus Mixtures

MixturesPure Substances

Every piece of matter is the same

More than one type of matter mixed together

Matter is classified as either a pure substance or a mixture

Elements versus Compounds

CompoundElements

Every atom is the same type of atom

More than one type of atom chemically bonded together.

Every molecule is the same.

Pure substances are either elements or compounds

Elements

Pure substanceEvery atom is the same

Elements can be found on the periodic table!

Element

Single AtomCannot be separated by chemical or physical processes

Compounds

Pure substanceEvery molecule is the same

Compound

Single Molecule

Made of more than one type of atom bonded together

Can be separated by chemical reactions only

Mixtures

HeterogeneousHomogeneous (aka “solution”)

It looks the same throughout

Different matter can be seen (chunks, bubbles, floaties,

layers, etc.)

Mixtures can be classified as homogeneous or heterogeneous

Mixtures

Not a pure substancePhysical combination of more than 1 type of pure substance

Mixture

>1 different type of matter

Can be separated chemically or physically

Mixture possibilities

• Mixtures can be any combination of solids, liquids and gases:– Solid-solid: Medicine tablet– Solid-gas: Pop Rocks candy– Solid-liquid: Ice water– Liquid-liquid: Lemon water– Gas-Liquid: Carbonated water– Gas-Gas: Air

True solutions, Colloids & Suspensions

ColloidTrue Solution

Particles don’t settle out and are

too small to scatter light

Particles don’t settle out but are large enough to

scatter light

Suspension

Particles will settle out over time

Dissolved Particle Size Increases

Particles Scattering Light

• If the dissolved particles are large enough to scatter light, we say it exhibits the “Tyndall Effect”

SolutionLight passes through unchanged

Colloids exhibit the Tyndall EffectLight is scattered by larger solute particles

Connect these concepts with Antacids

• What type of matter do you think antacids are?– Pure substance (Element or compound)– Mixture (homogeneous or heterogeneous)

Let’s Practice

Tin foilExample:

Determine if each is element,

compound, homogeneous or heterogeneous

mixtures

Copper pipe

Concrete

Carbon tetrachloride

Sports drink

Section 2.2—Naming Chemicals

We need to be able to name the chemicals in the antacids!

Matter can be classified

Matter

Pure Substances

Mixtures

Element CompoundHomogeneous

(Solutions)Heterogeneous

Matter

• Anything that has mass and takes up space• Anything made from atoms• Examples:

– Molecules– Cells– People– Air– Water

Pure Substances versus Mixtures

MixturesPure Substances

Every piece of matter is the same

More than one type of matter mixed together

Matter is classified as either a pure substance or a mixture

Elements versus Compounds

CompoundElements

Every atom is the same type of atom

More than one type of atom chemically bonded together.

Every molecule is the same.

Pure substances are either elements or compounds

Elements

Pure substanceEvery atom is the same

Elements can be found on the periodic table!

Element

Single AtomCannot be separated by chemical or physical processes

Compounds

Pure substanceEvery molecule is the same

Compound

Single Molecule

Made of more than one type of atom bonded together

Can be separated by chemical reactions only

Mixtures

HeterogeneousHomogeneous (aka “solution”)

It looks the same throughout

Different matter can be seen (chunks, bubbles, floaties,

layers, etc.)

Mixtures can be classified as homogeneous or heterogeneous

Mixtures

Not a pure substancePhysical combination of more than 1 type of pure substance

Mixture

>1 different type of matter

Can be separated chemically or physically

Mixture possibilities

• Mixtures can be any combination of solids, liquids and gases:– Solid-solid: Medicine tablet– Solid-gas: Pop Rocks candy– Solid-liquid: Ice water– Liquid-liquid: Lemon water– Gas-Liquid: Carbonated water– Gas-Gas: Air

True solutions, Colloids & Suspensions

ColloidTrue Solution

Particles don’t settle out and are

too small to scatter light

Particles don’t settle out but are large enough to

scatter light

Suspension

Particles will settle out over time

Dissolved Particle Size Increases

Particles Scattering Light

• If the dissolved particles are large enough to scatter light, we say it exhibits the “Tyndall Effect”

SolutionLight passes through unchanged

Colloids exhibit the Tyndall EffectLight is scattered by larger solute particles

Connect these concepts with Antacids

• Inactive ingredients might– Add enough volume to make the pill able to be

handeled– Add color– Add flavor– Allow the tablet to be compressed and formed

Let’s Practice

Tin foilExample:

Determine if each is element,

compound, homogeneous or heterogeneous

mixtures

Copper pipe

Concrete

Carbon tetrachloride

Sports drink

Section 2.2—Naming Chemicals

We need to be able to name the chemicals in the antacids!

Binary Ionic compounds

Definitions

Binary Ionic Compound- compound containing two elements—one metal and one non-metal

+Cation

+Cation

-Anion

-Anion Ionic Compound

Ionic bond- bond formed by attraction between + and - ions

Metals & Non-MetalsIonic Bonds are between metals & non-metals

H He

Li Be B C N O F Ne

Na Mg Al Si P S Cl Ar

K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr

Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe

Cs Ba Lu Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn

Fr Ra Lr Rf Db Sg Bh Hs Mt Uun Uuu Uub Uut

Metals Metalloids Non-metals

These compounds have:2 elements (“binary”)A metal & a non-metal (“ionic”)

To name these compounds:Write the name of the metal (the cation)Write the name of the non-metal (the anion) with

the suffix “-ide”

Identifying & Naming Binary Ionic

The subscripts in the formula do not matter when naming this type

Example #1

NaCl

Cation

Anion

“Sodium”

“Chlorine” becomes “Chloride”

Sodium Chloride

Example #2

Cation

Anion

“Calcium”

“Bromine” becomes “Bromide”

CaBr2

Calcium Bromide

Example #3

K2O

Cation

Anion

“Potassium”

“Oxygen” becomes “Oxide”

Potassium Oxide

Let’s Practice

Example:Write the name for the following

compounds

CaF2

Na3P

NaCl

SrBr2

Polyatomic Ionic Compounds

Definition

Polyatomic Ion- more than one atom that together have a charge

+Cation

+Cation

Polyatomic Ionic Compound- compound containing at least one polyatomic ion

-Polyatomic

Anion

Polyatomic IonicCompound

Common Polyatomic Ions

COMMON POLYATOMIC IONS

Acetate, CH3COO-1 or C2H3O2-1

Ammonium NH4+1

Bromate, BrO3-1

Bromite, BrO2-1

Carbonate, CO3-2

Carbonite, CO2-2

Chlorate, ClO3-1

Chlorite, ClO2-1

Chromate, CrO4-2

Cyanide, CN-1

Dichromate, Cr2O7-2

Dihydrogen phosphate, H2PO4-1

Hydrogen carbonate or bicarbonate, HCO3

-1

Hydrogen phosphate or biphosphate, HPO4

-2

Hydrogen sulfate or bisulfate, HSO4-1

Hydroxide, OH-1

Hypochlorite, ClO-1

Iodate, IO3-1

Iodite, IO2-1

Nitrate, NO3-1

Nitrite, NO2-1

Oxalate, C2O4-2

Perchlorate, ClO4-1

Permanganate, MnO4

-1

Peroxide, O2-2

Phosphate, PO4-3

Phosphite, PO3-3

Silicate, SiO3-1

Sulfate, SO4-2

Sulfite, SO3-2

The Appendix of your book (Page A-2) has the following chart

The only cation (front-half) polyatomic ion is “NH4”

All other polyatomic ions are anions (back-half)

The subscripts within the polyatomic ion is important (it must match exactly with the one on your ion list)

If there are parenthesis, the polyatomic ion is inside (ignore the number outside)

Help Identifying Polyatomic Ions

Practice Identifying Polyatomic Ions

Example:Identify and

name the polyatomic ion in each compound

NaNO3

NH4Cl

Ca(OH)2

(NH4)3PO4

K2CO3

These compounds have:More than 2 capital letters (non starting with H)Contain at least 1 metal & 1 non-metal

To name these compounds:Write the name of the cation (the metal element

name or “Ammonium” for “NH4”)If the anion is a polyatomic ion, write the polyatomic

ion’s name just as it isIf the anion is a single non-metal element, write its

name with the suffix “-ide”

Identifying & Naming Polyatomic Ionic

Example #4

NaNO3

Cation

PolyatomicAnion

“Sodium”

“Nitrate”

Sodium Nitrate

Example #5

Cation

PolyatomicAnion

“Potassium”

“sulfate”

K2SO4

Potassium sulfate

Example #6

Ca(OH)2

Cation

PolyatomicAnion

“Calcium”

“hydroxide”

Calcium hydroxide

Let’s Practice

Example:Write the name for the following

compounds

Ca(NO3)2

Na3PO4

NH4ClO

K2CO3

Multivalent Metals

Definition

Multivalent Metal- metal that has more than one possibility for cationic charge

The Appendix of your book (Page A-2) has the following chart

Common multivalent metals and their charges

Cobalt Co+2 Co+3

Copper Cu+1 Cu+2

Iron Fe+2 Fe+3

Lead Pb+2 Pb+4

Manganese Mn+2 Mn+3

Mercury Hg2+2 Hg+2

Tin Sn+2 Sn+4

These compounds have:One of the multi-valent metals in that chart

To name these compounds:Write the name of the metal element (cation)Write the name of the anion (element name with “-ide” or

polyatomic ion name)Determine the total negative chargeTotal negative charge = total positive charge for all neutral

compoundsDetermine the charge on each metal atomWrite the charge in roman numerals in parenthesis after the

metal’s name

Identifying & Naming Multivalent Metals

Common Ions

N3-

O2-

F-

P3-

S2-

Cl-

Se2-

Br-

I-

Periodic table--Charges of common ions

Use the periodic table to determine charges on common elemental anions

Example #8

CuCl

Cation

Anion

“Copper”

“Chlorine” becomes “Chloride”

Copper Chloride

Chloride has a –1 charge

-1 charge * 1 ion = -1

A –1 charge needs a +1 charge

Therefore, copper must be +1

(I)

Example #9

Fe2(CO3)3

Cation

Polyatomic Anion

“Iron”

“Carbonate”

Iron carbonate

Carbonate has a –2 charge

-2 charge * 3 ions = -6

A –6 charge needs a +6 charge and there are 2 iron ions

Therefore, iron must be +3

(III)

Let’s Practice

Example:Write the name for the following

compounds

PbCl2

PbCl4

MnO

Mn2O3

Binary Covalent Compounds

Definition

Binary Covalent Compound compound made from two non-metals that share electrons

NonmetalNon

metalNon

metalNon

metal Covalent compound

Covalent bond atoms share electrons

These compounds have:2 elements (“binary”)Both non-metals (“covalent”)

To name these compounds:Write the name of the first element with the prefix

indicating the number of atoms (except don’t use “mono-”)

Write the name of the second element with the prefix indicating the number of atoms (including “mono-”) and the suffix “ide”

Identifying & Naming Binary Covalent

Covalent PrefixesThe Appendix of your book (Page A-2) has the following chart

PREFIXES USED IN MOLECULAR COMPOUNDS1. mono-

2. di-3. tri-

4. tetra-5. penta-6. hexa-7. hepta-8. octa-9. nona-10.deca-

Example #10

P2O5

Phosphorus

Oxygen

2 = “di-”

5 = “penta-”Use “-ide”

Diphosphorus pentaoxide

Example #11

Silicon

Oxygen

Don’t use “mono-” on first element

2 = “di-”Use “-ide”

SiO2

Silicon dioxide

Let’s Practice

Example:Write the name for the following

compounds

CO2

N2O4

P4O10

CO

Nomenclature Summary

Naming Chemical Formulas

Starts with a metal or NH4

Does not contain a metal = Binary

Covalent compound

2 capital letters = Binary Ionic

More than 2 elements = Polyatomic Ionic

Mixed Practice

Example:Write the name for the following

compounds

Na2O

K3PO4

Cu(OH)2

(NH4)2S

MgCl2

Section 2.3—Chemical Formulas

We need to be able to read the formulas for chemicals in the antacids!

Your Appendix (Page A-2) has lists of:Common polyatomic ionsMultivalent metalsCovalent prefixes

Use your periodic table to determine the charges of common elements when they form ions

Reminders from Section 2.2

Binary Ionic compounds

Definitions

Binary Ionic Compound- compound containing two elements—one metal and one non-metal

+Cation

+Cation

-Anion

-Anion Ionic Compound

Ionic bond- bond formed by attraction between + and - ions

Metals & Non-MetalsIonic Bonds are between metals & non-metals

H He

Li Be B C N O F Ne

Na Mg Al Si P S Cl Ar

K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr

Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe

Cs Ba Lu Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn

Fr Ra Lr Rf Db Sg Bh Hs Mt Uun Uuu Uub Uut

Metals Metalloids Non-metals

Example #1

Sodium chloride

Cation

Anion

Na+1

Cl-1

NaCl

Na+1Cl-1

+1 + -1 = 0

The compound is neutral…no subscripts are needed.

Example #2

Calcium bromide

Cation

Anion

Ca+2

Br-1

CaBr2

Ca+2Br-1

+2 + -1 = +1

Ca+2Br-1Br-1

The subscript “2” is used to show that 2 anions are needed.

+2 + -1 + -1 = 0

Let’s Practice

Example:Write the following chemical formulas

Cesium chloride

Potassium oxide

Calcium sulfide

Lithium nitride

Polyatomic Ionic Compounds

Definition

Polyatomic Ion- more than one atom that together have a charge

+Cation

+Cation

Polyatomic Ionic Compound- compound containing at least one polyatomic ion

-Polyatomic

Anion

Polyatomic IonicCompound

These compounds:Do not end with “-ide” (except hydroxide & cyanide)Do not use covalent prefixes

To write these formulas:Write the symbol & charge of the cation & anionAdd additional cations or anions to have a neutral compoundUse subscripts to show the number of ions

When using subscripts with a polyatomic ion, you must put the polyatomic ion in parenthesis.

Identifying & Naming Polyatomic Ionic

Example #3

Sodium carbonate

Cation

PolyatomicAnion

Na+1

CO3-2

Na2CO3

Na+CO32-

+1 + -2 = -1

Na+Na+CO32-

The subscript “2” is used to show that 2 cations are needed.

+1 + 1 + -2 = 0

Example #4

Magnesium nitrate

Cation

PolyatomicAnion

Mg+2

NO3-1

Mg(NO3)2 Use parenthesis when adding subscripts to polyatomic ions

Mg+2NO3-

+2 + -1 = 1

Mg+2NO3- NO3

-

The subscript “2” is used to show that 2 anions are needed.

+2 + -1 + -1 = 0

Let’s Practice

Example:Write the following chemical formulas

Sodium nitrate

Calcium chlorate

Potassium sulfite

Calcium hydroxide

Multivalent Metals

Definition

Multivalent Metal- metal that has more than one possibility for cationic charge

These compounds:Will have roman numerals

To write these formulas:Same as binary ionic or polyatomic ionic.The roman numerals tell the charge of the metal

(cation)

Identifying & Naming Multivalent Metals

Example #5

Iron (III) oxide

Cation

Anion

Fe+3

O-2

Fe2O3

Fe+3O2-

+3 + -2 = -1

Fe+3Fe+3O2-O2-

The subscript “2” and “3” are used to show the numbers of atoms needed.

+3 + 3 + -2 + -2 + -2 = 0

Example #6

Copper (II) nitrate

Cation

PolyatomicAnion

Cu+2

NO3-1

Cu(NO3)2

Cu+2NO3-

+2 + -1 = 1

Cu+2NO3-NO3

-

Use parenthesis when adding subscripts to a polyatomic ion

+2 + -1 + -1 = 0

Let’s Practice

Example:Write the following chemical formulas

Iron (II) nitrate

Copper (I) chloride

Lead (IV) hydroxide

Tin (II) oxide

Let’s Practice

Example:Write the following chemical formulas

Iron (II) nitrate

Copper (I) chloride

Lead (IV) hydroxide

Tin (II) oxide

Binary Covalent Compounds

Definition

Binary Covalent Compound compound made from two non-metals that share electrons

NonmetalNon

metalNon

metalNon

metal Covalent compound

Covalent bond atoms share electrons

These compounds:Use covalent prefixes

To write these formulas:Write the symbols of the first and second elementUse the covalent prefixes (assume the first element

is “1” if there’s no prefix) as the subscripts to show number of atoms.

Identifying & Naming Binary Covalent

Atoms do not form charges when bonding covalently…you DO NOT need to worry about charges with this type!

Example #7

Dinitrogen Tetraoxide

N

O

“Di-” = 2

“Tetra-” = 4

N2O4

Example #8

Silicon dioxide

Si

O

“Mono-” is not written for the first element

“Di-” = 2

SiO2

CAUTION!!!

bi-di-

Stands for “2” in covalent compounds

Means there’s a hydrogen in the polyatomic anion

“di” and “bi” do not mean the same thing!

Carbon dioxide = CO2 Sodium biphosphate = Na2HPO4

Let’s Practice

Example:Write the following chemical formulas

Carbon monoxide

Nitrogen dioxide

Diphosphorus pentaoxide

Nomenclature Summary

Writing Chemical Formulas

Does not contain covalent prefixes

Does contain covalent prefixes = Binary

Covalent compound

Ends with “-ide” (except hydroxide &

cyanide) = Binary Ionic

All others = Polyatomic Ionic

Mixed Practice

Example:Write the following chemical formulas

Magnesium hydroxide

Copper (II) nitrate

Iron (III) oxide

Nitrogen dioxide

Sodium bicarbonate

Section 2.4—Defining, Naming & Writing Acids & Bases

We need to know what acids behave when talking about ant-acids!

Acids

Acids – Arrhenius Definition

• Produce Hydronium ion (H3O+1) in water• Hydronium ion is water + a hydrogen cation

H

OH

water

H+1

H

OH

H +1

By this definition, if an acid is to give a H+1 to water, then all acids will have hydrogen as the cation (first element written).

How do Acids produce Hydronium?

H

OH

H -

water acid

Hydrogen cation with some anion

How do Acids produce Hydronium?

H

OH

H -+1

How do Acids produce Hydronium?

H

OH

H+1 -

Hydronium ion Anion

Naming Acids

These compounds have:Start with “H” (more than 1 “H” is OK, too).Do not contain oxygen

To name these compounds:Use “hydro____ic acid”Fill in the blank with the anion’s name without the

last syllable

Naming non-oxygen Acids

Example #1

HBr

Hydrogen cation

Bromine

It’s an acid

No oxygenUse “hydro___ic”

Hydrobromic acid

These compounds have:Start with “H” (more than 1 “H” is OK, too).Do contain oxygen

To name these compounds:Use “___ic acids” for “-ate” anionsUse “___ous acids” for “-ite” anions

Naming Oxygen Acids

Do not use “hydro” with these…the word “acid” is how you know it begins with hydrogen, not “hydro-”

Example #2

Hydrogen cation

Sulfite ion

It’s an acid

“-ite” ionUse “___ous” acid

H2SO3

Sulfurous acid

Example #3

Hydrogen cation

Sulfate ion

It’s an acid

“-ate” ionUse “___ic”

H2SO4

Sulfuric acid

Let’s Practice

Example:Write the name for the following

compounds

HCl

HNO3

H2S

H3PO3

Writing Acid Formulas

To write these formulas:The cation is H+1

Write the anion and chargeBalance the charges by adding the appropriate

subscript to the hydrogen cation

“Hydro-” acids

Example #4

Hydrofluoric acid

Hydrogen cation

Does not contain oxygen

H+1

F-1

HF

H+1F-1

+1 + -1 = 0

The compound is neutral.Subscripts are not needed

To write these formulas:The cation is H+1

If it is an “-ic” acid, the anion is the “-ate” polyatomic ion

If it is an “-ous” acid, the anion is the “-ite” polyatomic ion

Add subscript to the hydrogen cation to balance charges

NON “Hydro-” acids

Example #5

Carbonic acid

Hydrogen cation

From the “___ate” anion

H+1

CO3-2

H2CO3

H+CO32-

+1 + -2 = -1

H+H+CO32-

+1 + 1 + -2 = 0

Example #6

Nitrous acid

Hydrogen cation

From the “___ite” anion

H+1

NO3-1

HNO2

H+NO2-

+1 + -1 = 0

Let’s Practice

Example:Write the

formula for the following acids

Phosphoric acid

Hydroiodic acid

Carbonous acid

Perchloric acid

Bases

Bases – Arrhenius Definition

• Bases produce the hydroxide ion in water

HO-1

Hydroxide Ion

Naming & Writing Bases

Most bases are just ionic compounds with “hydroxide” as their anion

The most common exception to this is ammoniaNH3 (ammonia) is a base even though it doesn’t

contain “-OH” as the anion

Naming Bases

Example #7

NaOH

Sodium

Hydroxide

Sodium Hydroxide

Let’s Practice

Example:Write the

formula or name for each

Ca(OH)2

KOH

Sr(OH)2

Copper (II) hydroxide

Magnesium hydroxide

Section 2.5—Characteristics of Acids and Bases

Now that we know what acids are, how do they act?

Characteristics of Acids & Bases

BasesAcids

Produce H3O+1 (hydronium ion) in water

Produce OH-1 (hydroxide ion) in water

Tastes sour Tastes Bitter

React with active metals to form hydrogen gas Feels slippery

Strength versus Concentration

Review of how acids produce ions

H

OH

H+1 -

Hydronium ion Anion

Strong versus Weak Acids

+

++

-

-

-

Strong acidMost of the acid molecules

have donated the H+1 to water

How many hydronium ion – anion pairs can you find?

How many intact acid molecules can you find?

3

1

Strong versus Weak Acids

+

-

Weak acidOnly a few of the acid

molecules have donated the H+1 to water

How many hydronium ion – anion pairs can you find?

How many intact acid molecules can you find?

1

3

Concentrated versus Dilute

solute solvent

Lower concentration

Not as many solute (what’s being dissolved) particles

Higher concentration

More solute (what’s being dissolved) particles

Combinations of Concentration & Strength

DiluteConcentrated

A lot of acid added & most

dissociates

Not much acid added, but most of

what’s there dissociates

A lot of acid added, but most

stays together

Not much acid added and most of what is there stays

together

Strong

Weak

All of the same ideas apply to bases as well (concentration and strength)

Many people think all acids are dangerous and all bases are more safeVinegar is an acid we eat…some of them are safe!Sodium hydroxide is a very caustic base…not all of

them are less harmful than acids!The stronger and acid or base is (and the more

concentrated it is), the more dangerous it is for you

Other notes

pH

Is a scale to measure the acidity of a sample

pH Scale

1 14

Highly acidic Very basic (not acidic)

neutral

7

Chapter 6 will give more detail about how pH is calculated!

Indicators change color based on pHLiquid indicators – various indicators change colors at different

pH’sUniversal indicator – a combination of liquid indicators to

produce a “rainbow” changing colors at several pH’sPaper Indicators

Paper with a liquid indicator on it (Litmus paper or pH paper)pH meters or pH probes

Electronically determine pH and give a read-out

Ways to measure pH

Common pH indicators

This picture © 1998 David Dice

pH of common substances

SUBSTANCE PH

0.1M HCl 1

Stomach contents

2

Vinegar 2.9

Soda pop 3

Grapes 4

Beer 4.5

Pumpkin pulp 5

Bread 5.5

Intestinal contents

6.5

Milk 6.5

Urine 6.6

Bile 6.9

Saliva 7

Blood 7.4

Eggs 7.8

0.1M NH3 (aq) 11.1

0.1M NaOH 13

Section 2.6—Chemical Reactions

If we’re going to do chemical reactions with antacids, we’d better know how to write them!

OO OO

Bonds and atoms are rearranged to form new compounds.

HH HH

OOHH

HHOOHH

HH HH HHThe compounds in the end are different from those in the beginning

Bonds are broken and formed between different atoms

2 H2 + O2 2 H2O

Chemical Reactions

Chemical Equations

The “sentence” of chemistry that shows how the starting materials and the final products of a chemical reaction

Examples of Chemical Equations

H Cl

HMg H

H Cl

Mg ClCl

H Cl

HMg H

H Cl

Mg ClCl

Word equation: magnesium metal is reacted with aqueous hydrochloric acid to produce aqueous magnesium chloride

and hydrogen gas

Visualization

Formula equation: Mg (s) + 2 HCl (aq) MgCl2 (aq) + H2 (g)

Parts of a Chemical Equation

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

Reactants

States of matter Arrow

Products

The starting materials for the reaction—each compound is separated by a “+”

s = solidl = liquidg = gasaq = aqueous (dissolved in water)

Read as:YieldsProducesFormsMakesetc.

Formed in the reaction

You must write each chemical formula correctly first! (Section 2.2)

“and”, “is mixed with” or “reacts with” = +“yield”, “produces” and “forms” =

Writing Chemical Equations

We will learn to balance equations in the next section, so don’t worry about it now!

Aluminum metal is reacted with hydrochloric acid to form aluminum chloride and hydrogen gas

Let’s Practice #1

Al + HCl AlCl3 + H2

Example:Write the word equation into symbol form

Copper (II) nitrate and sodium hydroxide form copper (II) hydroxide and sodium nitrate

Let’s Practice #2

Cu(NO3)2 + NaOH Cu(OH)2 + NaNO3

Example:Write the word equation into symbol form

NaCl + AgNO3 AgCl + NaNO3

Double Replacement ReactionsThe cations from two compounds replace each other.

ClClN

aNa

AgAg

OO OONN

OO

ClCl

AgAg

NaNa

OO OONN

OO

Two ionic compounds switch ions

Double Replacement Reactions

A X B Z A XBZAA XX BB ZZ AA XXBBZZ

General format of a double replacement reaction:

& balance charges with subscripts when writing formulasRemember to write cations first …

AgCl

CaCl2 + AgNO3

3

Ca(NO3)2 +CaCl2 AgNO3+

Products of a Double Replacement

Only leave subscripts that are in the original compound there if they are a part of a polyatomic ion!

Neutralization Reactions

General format of a neutralization reaction:

X B XBH HO HO

HXX BB XXBBH HOO HO

HH

OOH

Neutralization reactions are double replacement reactions where one cation is “H” and one anion is “OH” and water is formed

& balance charges with subscripts when writing formulasRemember to write cations first …

HOH

H2 SO4 + NaOH

3

Na2SO4 +H2 SO4 NaOH+

Products of a Neutralization Reaction

Only leave subscripts that are in the original compound there if they are a part of a polyatomic ion!

You can write the water as “HOH” when you combine the cation & anion or you can change it to “H2O”

Let’s Practice #3

SrBr2 + HOH

Example:Write the

products for this reaction

Sr(OH)2 + HBr

Let’s Practice #4

CaCl2 + HOH

Example:Write the

products for this reaction

HCl + Ca(OH)2

Section 2.7—Balancing Equations

We need to finish writing those equations we started!

Law of Conservation of Matter/Mass

Law of Conservation of Matter – Matter cannot be created nor destroyed during chemical or physical changes

Also called the Law of Conservation of Mass (since all matter has mass)

How Does the Law Lead to Balancing?

Law of Conservation

of MatterTherefore… So we must…

Matter cannot be created nor destroyed during a chemical or physical change

The matter on the reactants side and the matter one the products side must be the same

Ensure the numbers of each type of atom are the same on both sides of the equation…by balancing!

How do we Balance Equations?

2 H2 + O2 2 H2O

Subscripts

Coefficients

# of atoms in a compound

Number of compounds in the reaction

Subscripts balance charges within a compound.

Coefficients balance atoms in an equation

What do Coefficients Really Mean?

CH4 + 2 O2 CO2 + 2 H2O

Total:1 C4 H4 O

Total:1 C4 H4 O

The equation is balanced.

H

C

H

HH

O O

O O

CO O HO

H

HO

H

H

CC

H

HH

O O

O O

CCO O HO

H

HO

H

How to Balance Chemical Equations

4

Filling each coefficient location lets you and the grader know that you finished the problem rather than you left some blank because you weren’t done!

Place a “1” in any empty coefficient location

_____ __________2

How to Balance By Inspection:

Reactants Products

H

O

4

2 3

2

C 1 1

2

4

44

1 1CH4 + O2 _____ H2 O CO2+

Choosing the Order of Balancing

Save for laterElements that are uncombined

Save for laterElements that appear more than 1 time per side

StartElements that appear

only 1 time per side

StartElements in most

complicated molecules

How do you know what order to balance in?

Pb + PbO2 + H+ Pb2+ + H2O

To balance this equation, use the order: O, H, Pb

2

_____

What about a different order?How is it different if we balance in a different order?

Reactants Products

O

Pb

2

2 1

1

H 1

2

2

_____ __________1 21 2Pb Pb+ O2 H2 O Pb2++H+_____2+

2 4

4

4

You’ll still get to the correct answer, but it will take longer and be more complicated!

H, O, Pb

Polyatomic Ions

Polyatomic ion – Group of atoms that together has a net charge

e.g. Nitrate NO31-

Carbonate CO32-

5 Place a “1” in any empty coefficient location

__________ __________2

Balancing with Polyatomic Ions:

Reactants Products

PO4

Ca

1

1 3

2

H 3 1

1

6

3

3 6Ca (OH)2+H3 Ca3 (PO4)2 H2O+PO4

OH 2 1

HOH

6

2

6 6

Let’s Practice #1

Example:Balance the

following equation

__ HCl + __ Ca(OH)2 __ CaCl2 + __ H2O2 1 1 2

HOH

Did you see the “OH” polyatomic ion & change H2O to HOH?

Let’s Practice #2

Example:Balance the

following equation

__ H2 + __ O2 __ H2O2 1 2

Let’s Practice #3

Example:Balance the

following equation

__ Fe + __ O2 ___ Fe2O34 3 2

Section 2.8—Speeding Up A Reaction

How can we make those antacid reactions occur faster?

Kinetics & Reaction Rates

Kinetics – Study of the rates of reactions

Reaction Rate – Rate at which reactants produce products

Collision Theory

Collision Theory – Defines 3 circumstances to be met for a reaction to occur.

Reactants must collide

Collision must be at the correct orientation

Collision must have minimum energy for reaction to occur

1

2

3

Only a small number of collisions meet the requirements and result in a reaction

Collisions Must Occur

In order for two molecules to react, they must come in contact with one another

FF

FFNN

OO

OO

There’s no way they’ll ever react if they don’t run into one another!

NNOO

OO

FF

FF

Collision with Correct Orientation

For a collision to result in a chemical reaction, it must occur with the correct orientation

FF FF NNOO

OO

This is the correct orientation. The reaction will happen.

FF

FF

This collision had more energy (faster moving molecules). A reaction will occur..

NNOO

OO

Collision with Enough Energy

For a collision to result in a chemical reaction, it must occur with the minimum energy for reaction

FF FF NNOO

OO

Activation Energy

Minimum energy for reaction to occur during a collision

Reaction Coordinate Diagram

Products

Activated complex(Also called the transition state)

Activation Energy

ReactantsEnergy change for reaction

Reaction coordinate diagrams show the energy changes throughout the reaction

Reaction proceeds

Ene

rgy

F + FNO2

FF

FF

Activated Complex

What is an “activated complex”?

Reaction proceeds

Ene

rgy

NNOO

OOFF FF NN

OO

OO

ReactantsActivated Complex

Products

F2 + NO2

F2NO2

Factors Affecting Reaction Rates

Surface Area of ReactantsHow does the surface area of the reactants affect the reaction rate?

Reactants must collide in order to react

Larger surface area means more particles can come in contact with each other at the same time

More reactants can collide at the same time and a fraction of those will result in reaction

As surface area increases, reaction rate increases

Concentrations of ReactantsHow does the concentration of reactants affect the reaction rate?

Only a small fraction of the collisions meet the requirements and result in a reaction

More reactants mean more collisions will occur

If more collisions occur, more will meet the requirements and result in a reaction

As reaction concentration increases, reaction rate increases

Temperature

How does temperature affect the reaction rate?

Reactants must collide with at least energy equal to the activation energy

If molecules are at a higher temperature, they have a higher average kinetic energy

With higher energy molecules, collisions will have higher energy and more often result in reaction

For most reactions, as temperature increases, reaction rate increases

Catalysts

Catalysts – Substance that increases the rate of reaction without being used up

A + B + C D + C

“C” is the catalyst…it is present in the beginning and in the end

Enzymes are catalysts in the body

Catalysts

How do catalysts help speed up the reaction without being used?

They increase the chances that a collision will successfully produce a reaction

For example, catalysts hold one or more of the reactants in place to allow collisions to occur with the correct orientation

Once the reaction has occurred, the catalyst releases the molecule(s) and finds another one to help

Catalysts & Reaction DiagramsReaction Path without catalyst

Reaction Path with catalyst

Reaction proceeds

Ene

rgy

Catalysts lower the activation energy of the reaction by letting it proceed in a different way.

With lower activation energy, a higher percentage of collisions will be successful (they don’t need to collide with as much energy to be successful)

What did you learn about antacids?

Antacids

MixtureMixture

Are a

CompoundsCompounds

ChemicalFormulas

ChemicalFormulas

Collision Theory

Collision Theory

Acids & BasesAcids & Bases

Chemical ReactionsChemical Reactions

Of differentSymbolizedwith

Some are

Balanced Chemical Equations

Balanced Chemical Equations

undergo

Symbolizedwith

Used in

Speed governed by