POWERPOINT UNIT 14

REACTION RATES Some Terminology to Know…

Reaction Rate The rate of disappearance of a reactant or appearance of a product

Temperature Increasing temperature increases the average kinetic energy of particles This increases the number of collisions between reactants

Concentration Concentration in terms of Molarity Increasing concentration increases the chance of particle collisions This increases reaction rate

Stirring Stirring a solution makes the reactants contact each other more often and increases reaction rate

Surface Area Increasing surface area increases reaction rate More surface area increases contact between reactants

Catalyst A substance that increases reaction rate without being consumed during the reaction

IDENTIFICATION Some things we will need over the next week or so…

Identifying Metals Metals are single elements found on the left side of the periodic table Separated from non-metals by metalloids (staircase) Examples Al Li Can you name any other ones?

Identifying Carbonates Carbonates end with the elements “CO 3 ” Examples Na 2 CO 3 MgCO 3

Identifying Salts Salts are two elements bonded together from opposite sides of the periodic table or with a polyatomic ion What is polyatomic ions? Examples NaCl AlF 3 KNO 3

And others… ACIDS AND BASES

Acids ~ Background For thousands of years people have known that vinegar, lemon juice and many other foods taste sour. However, it was not until a few hundred years ago that it was discovered why these things taste sour – They taste sour because they are all acids. The term acid, in fact, comes from the Latin term acere, which means "sour"

Acid Characteristics Acids have a PH of less than 7. Acids taste sour Acids are corrosive to metals Acids can ‘burn' your skin Acids change litmus paper red Litmus paper helps to determine acids and bases Acids become less acidic when mixed with bases.

Examples of Acids orange juice, lime juice or lemon juice (citric acid) vinegar (acetic acid) aspirin (salicylic acid) yogurt (lactic acid) Coca-Cola (phosphoric acid) toilet bowl cleaner (sulfuric acid) bathroom cleaner (muriatic acid) wine (tartaric acid and/or malic acid) vitamin C tablets (ascorbic acid) urine (uric acid)

Identifying Acids Acids start with “H” Examples: HCl - hydrogen chloride or hydrochloric acid H 2 SO 4 – hydrogen sulfate or sulfuric acid

Bases Bases can also be called alkalis. Bases can be thought of as the chemical opposite of acids. A reaction between an acid and base is called neutralization We will talk about more next week. An example of base: soap

Base Characteristics Bases have a pH more than 7 Bitter Bases feel slippery Converts fats and oils in skin to glycerin (slick feel) In a sense, bases dissolve your skin… think of getting Clorox bleach on your skin Bases turns litmus paper to a blue color. Bases become less basic when mixed with acids. Bases reacts with acids to form salt and water

Base Examples Mustards Many medicines Ie. Magnesium oxide – treats indigestion Bleaches, soaps, toothpastes, window cleaners and other cleaning agents Sodium Hydrogen Carbonate (bread soda). Sodium hydroxide (NaOH) or caustic soda Calcium hydroxide ( Ca(OH) 2 ) or limewater Ammonium hydroxide (NH 4 OH) or ammonia water Magnesium hydroxide ( Mg(OH) 2 ) or milk of magnesia

Identifying Bases Bases end in “OH” (hydroxides) Examples: NaOH Ca(OH) 2

INDICATORS

Indicators Is added to the solution to determined pH (acidity or basicity) visually

NAMING ACIDS & BASES Guidelines

Naming Acids Binary: Acid made out of 2 elements. H + _________ Hydro________ic Acid

Some Practice H 2 S HBr H 3 P HCl Hydrosulfuric Acid Hydrobromic Acid Hydrophosphoric Acid Hydrochloric Acid

Naming Acids Tertiary: Acid containing 3 elements. H + _______ + O

Rules for Tertiary Acids:  To name acids that contain the –ate polyatomic ions, change the ending to –ic acid. (Polyatomic) - ate + -ic Acid

Practice: H 2 SO 4 HClO 3 HNO 3 H 3 PO 4 Sulfuric Acid Chloric Acid Nitric Acid Phosphoric Acid

Rules for Tertiary Acids:  To name the acids that contain the –ite polyatomic ions, change the ending to –ous acid. (Polyatomic) - ite + -ous Acid

Practice H 2 SO 3 HClO 2 HNO 2 Sulfurous Acid Chlorous Acid Nitrous Acid

Practicing Naming Acids FormulaBinary or Ternary Name HClBHydrochloric Acid HIBHydroiodic Acid HNO 3 TNitric Acid H 2 SO 4 TSulfuric Acid H 3 PO 4 TPhosphoric Acid H 2 CO 3 TCarbonic Acid

Naming Bases Use the same rules as for polyatomic ions (name the cation, then name the anion) Name the metal first Add Hydroxide Ex:NaOH = Sodium Hydroxide KOH = Potassium Hydroxide

Practice Naming Bases FormulaName NaOHSodium Hydroxide KOHPotassium Hydroxide Mg(OH) 2 Magnesium Hydroxide Al(OH) 2 Aluminum Hydroxide NH 4 OHAmmonium Hydroxide

REACTIONS WITH ACIDS

Let’s Review… How do we know which chemicals are… Bases? Acids? Carbonates? Salts? Metals?

Let’s practice~ Classify the following chemicals… Chemicals: NaClHClLi 2 CO 3 MgKOHAg MgCO 3 BeF 2 Al(OH) 3 Groups: MetalsAcid Bases CarbonatesSalts

Review Writing Formulas Let’s practice: Lithium iodide Magnesium hydroxide Hydrogen gas Sodium Calcium carbonate

Review Balancing Equations ___ NaNO 3 + ___ PbO  ___ Pb(NO 3 ) 2 + ___ Na 2 O ___ AgI + ___ Fe 2 (CO 3 ) 3  ___ FeI 3 + ___ Ag 2 CO­ 3

ACIDS REACT WITH METALS Acid is a compound, metal is an element… So what type of reaction? HCl + Li  _________ + __________ HF + Mg  _________ + _________ H 2 S + Al  _________ + _________ Therefore… Acid + Metal  salt + H 2

ACIDS WITH CARBONATES Acid is a compound, carbonate is an compound… So what type of reaction? HCl + MgCO 3  ________ + _________ HI + Li 2 CO 3  ________ + ________ H 2 S + Na 2 CO 3  _______ + _________ Acid + Carbonate  salt + CO 2 + H 2 O

P H SCALE

pH Scale Study the pH chart given below carefully. Note that each decrease in pH by one pH unit means a tenfold increase in the concentration of hydrogen ions.

pH Scale Hydronium ion - H 3 O + More H 3 O + = more acidic Hydroxide ion - OH - More OH - = more basic

Formula: pH = -log [H 3 O + ] Find the pH if the hydronium ion concentration is: 1.00 x M 3 x M  9.18 pH and Hydronium Ion Concentration

Formula:pH = -log [H 3 O + ] Therefore, to solve for pH: [H 3 O + ] = 10 -pH Find the hydronium ion concentration pH = 3.0  1.0 x M pH = 10.0  1.0 x M pH = 6.6  2.5 x M pH and Hydronium Ion Concentration Some more practice

Formula: pH + pOH = 14 Find the pH pOH = 2.0  pH = 12.0 pOH = 11.2  pH = 2.8 pH and pOH

Formula:pOH = -log[OH - ] Therefore to calculate [OH - ] = 10 -pOH To calculate pH from [OH - ]: Use the above formula calculate pOH Then calculate pH using 14 = pOH + pH pH and Hydroxide Ion Concentration

Determine the pH of solutions with the following [OH - ]: 1.0 x M  x M  pH and Hydroxide Ion Concentration Some more practice

Some common stuff…

Some more practice… Fill in the table: [H 3 O + ][OH - ]pHpOH 1.2 x x

TITRATIONS

ACIDS and BASES REACTIONS What distinguishes acids? What distinguishes bases?

ACIDS and BASES Acid is a compound, base is an compound… So what type of reaction? __ HCl + __ NaOH  __ NaCl + __ HOH H 2 O __ HF + __ Ca(OH) 2  __Ca F 2 + __ H 2 O Acid + Base  salt + H 2 O

Titration Neutralizing an acid or base M A x V A = M B x V B M = molarity V = volume A = acid B = base

Practice If you add 10mL of acid to 20mL of a.10M basic solution, what will the molarity of the acid be? M A x V A = M B x V B Lets look at volume and molarity… Less concentrated, we need more More concentrated, we need less