Unit 2b: Antacids: adapted from Kendall Hunt Chemistry You Need to Know

2.5 Characteristics of Acids and BasesAcids Bases

Produces: Produces:

Tastes: Tastes:

Reacts with : Feels:

Strong: Weak:

Dilute: Concentrated:

Combinations of Strength and Concentration

pH scale

Concentrated Dilute

Strong

Weak

o measures the acidity of a sampleo range: ________to ________o Most acidic: _______o Most basic: _______o Neutral: __________

Measuring pHo Indicators change color based on pH

o Liquid indicators ( phenolphthalein or universal indicator)

o Paper indicator (litmus or pH paper)

o pH probes or pH meters :

Common substances and their pH valuesstomach acid vinegar grapes milk

saliva blood ammonia

2.6 Chemical Reactions Chemical reactions

o Chemical equations

o The ___________of chemistry shows the ________________________and the ________________of a chemical reaction.

Examples of Chemical Reactionso Word equation: Magnesium metal is reacted with aqueous hydrochloric acid to produce magnesium chloride and hydrogen gaso Formula equation: o Visualization

o Observations that classify the change as a chemical reaction

Parts of a chemical equation

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

Solid (s) yieldsLiquid (l) formsGas (g) producesAqueous (aq) dissolved in water

You must write the correct _______________for each reactant and product. Common phrases such as “and”, “is mixed with”, “reacts with” are replaced with a

________ sign. Phrases such as “yield”, “produces”, and “forms” are replaced with a _______.

Examples: a. Aluminum metal is reacted with hydrochloric acid to form aluminum chloride and hydrogen

gas.

b. Copper (II) nitrate and sodium hydroxide react to form copper (II) hydroxide and sodium nitrate.

Synthesis Reactionso General format:

3 models

A. Formation of a Binary Compound: What do you do? Bring symbols together and check charges

A + B AB

Element + Element Binary Ionic Compound

Examples:

1. K + Br2

2. Sr + N2

B. Metal-oxide and Water reactions:What to do? Combine metal symbol with OH and check charges

MO + H2O base

Metal oxide + water metal hydroxide

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Reactants Products

Examples:

1. CaO + H2O

2. Fe2O3 + H2O

C. Nonmetal-oxide and Water reactions:What to do? Add up all the atoms starting with H and ending with O

NMO + H2O acid

NONmetal oxide + water oxyacid

Examples:

1. CO2 + H2O

2. SO3 + H2O

Decomposition Reactions o General format:

A. Binary Compound : What do you do? Break binary compound into the 2 elements that make it up***** LOOK FOR DIATOMIC MOLCULES*****

AB A + B

Binary Ionic Compound Element + Element

Examples:

1. CaCl2

2. FeS

B. Metallic Carbonates :What to do? Place the metal next to oxygen & check charges. Then form carbon dioxide

MCO3 MO + CO2

Metal carbonate metal oxide + carbon dioxide

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Examples:

1. K2CO3

2. Fe2(CO3)3

C. Metallic Hydrogen Carbonates :What to do? Place the metal next to oxygen & check charges. Then form water.

MHCO3 MO + H2O + CO2

Metal hydroxide metal oxide + water + carbon dioxide

Examples:

1. NaHCO3

D. Metallic Hydroxides :What to do? Place the metal next to oxygen & check charges. Then form water.

MOH MO + H2O

Metal hydroxide metal oxide + water

Examples:

1. LiOH

2. Ca(OH)2

E. Metallic chlorates :What to do? Place the metal next to chlorine & check charges. Then form oxygen.

MClO3 MCl + O2

Metal chlorate metal chloride + oxygen

Examples:

1. AgClO3

2. Ca(ClO3)2

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F. Oxyacids: What to do? Remove the water and what is left over is the nm oxide.

Acid NMO + H2O

Acid nonmetal oxide + water

Examples:

1. H2SO3

Single Replacement Reactionso General format:

****** MUST CHECK ACTIVITY SERIES******a. Metal-Metal Replacement:

What do you do? Is the single metal above the other metal in the chart? YES: Replace it & check charges of new compound. Watch out for the diatomic molecules.NO: Write NR

Li + K2S LiS + K Element + compound compound + element

Examples:1. Zn + Cu(NO3)2

2. Cu + Ag2SO4

b. Active metal replacing Hydrogen from Water : What to do? Is the single element above the H in the chart? Look at specific rules!

YES: Replace it & check charges of new metal hydroxide and then add hydrogen gas NO: Write NR

M + H2O MOH + H2

Element + water base + elementExamples:

1. Na + H2O

2. Al + H2O

c. Active metal replacing Hydrogen from an Acid: What to do? Is the single element above the H in the chart? Look at specific rules!

YES: Replace it & check charges of new metal hydroxide and then add hydrogen g NO: Write NR

M + HX MX + H2

Element + acid compound + element

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Examples:1. Mg + HCl

d. Halide-Halide Replacement :What to do? Is the single halogen above the other halogen in the chart?

YES: Replace it & check charges of new compound. Watch out for diatomic molecules! NO: Write NR D + BC BD + C halogen + compound compound + halogen

Examples: 1. Cl2 + KBr

2. I2 + NaCl

Double Replacement Reactionso General format:

a. Formation of a Precipitate: What to do? Swap positive ions and check charges on new compounds. Check solubility rules to identify if there is a precipitate..

A B + CD CB + AD

compound + compound compound + compound

Examples:

1. NaCl + AgNO3

2. Pb(NO3)2 + KI

b. Acid –Base Neutralization Reaction: What to do? Swap positive ions and check charges on new compounds. Check solubility

rules to identify if there is a precipitate HX + MOH XOH + H2O

Acid + Base ionic comp + water

Examples:

1. KOH + H2SO4

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Combustion Reactionso General format: Hydrocarbon + O2 CO2 + H2O

a. Burning of a Hydrocarbon: What to do? Products are always carbon dioxide and water.

Examples:1. C3H8 + O2

2. CH3OH + O2

2.7: Law of Conservation of Matter/MassLaw of Conservation of Matter/Mass

Law of Conservation of Matter – Matter ___________________________________________ during ________________________________________

Also called the Law of Conservation of __________________________ (since all _________________________)

Must be same number of atoms of each element on left and right side of the equation. To ensure that the conditions of the Law of Conservation of matter are met, we must

________the equation. o Balancing an equation

_____________balance ____________________in a compound Make a _____________ Count the number of atoms of each element on the reactants side and on the

product side. Be sure to account for any subscripts. A subscript outside of a parenthesis will multiply all of the atoms inside the parenthesis by that factor.

Add coefficients to balance the numbers. Each time you add a coefficient, recount the atoms.

Place a “1” beside any formula that does not have a coefficient when the equation is balanced. This is the final step so that you will know the equation is finished.

CH4 + 2 O2 CO2 + 2 H2O R PC CH HO O

o Order of Balancing (how to get started) Start: Elements that appear_____________________ Start: Elements in most________________________ Save for later: elements that _________________per side. Save for later: elements that are ____________________.

o Chunk the polyatomic ions if they are on both sides of the equation. __________is a polyatomic ion that is sometimes “hidden” in ______________.

o Examples: _____HCl + ______Ca(OH)2 _____CaCl2 + ______H2O

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_____H2 + _____O2 _____H2O

_____Fe + _____O2 ____ Fe2O3

2.8: Speeding up a Reaction Kinetics:

Reaction rate:

Collision theoryo Defines 3 conditions to be met for a reaction to occur.

Reactants must _____________________.

Collision must be at the correct _____________.

Collision must have minimum _______________ for the reaction to occur.

(diagrams from The chemistry that you need to Know. K. Deters.)

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Factors that Affect Reaction Rateo Nature of Reactant: Some substances are just more reactive than otherso Surface area : As surface area increases, the reaction rate___________.

(Reactant particles must collide. Larger surface means more contact with each other. More particles can collide at the same time.)

o Concentrations of the Reactants: As reaction concentration increases, the reaction rate __________. (More reactants mean more collisions since only a small fraction of the collisions will meet the criteria.)

o Temperature: For most reactions, as temperature _________ the rate of the reaction will ____________________.(Reactants must have minimal energy (activation energy) to collide. At higher temperatures, the kinetic energy is higher and the collisions have higher energy. )

o Catalyst: substance that _____________the rate of reaction without being used up. Catalysts increase the chances that a collision will successfully produce a reaction by holding one or more of the reactants in place to ensure the correct orientation. Once the collision is over, the catalyst releases the molecule(s) and seeks another one.

(from K. Deters)

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