Acids, Bases, & Molarity

Chemistry 10 Mrs. Page

Learning Objectives Define acid and base according to Bronsted-Lowry

theory List the general characteristics of acids and bases. Name common binary acids and oxyacids given

their chemical formulas Define the terms solute, solvent, solution, solubility

and molarity Calculate molarity

ACIDS

Have you ever had a muscle cramp after working out?

This is a result of lactic acid building up in your muscles when oxygen is limited.

What is an acid? An acid is a substance that

produceds H+ ions in water.

According to the Bronsted-Lowry theory an acid is a proton donor

It comes from the Latin word acidus that means "sharp" or "sour".

The more H+ ions, the more acidic the solution.

Define acid and base according to Bronsted-Lowry theory

Properties of Acids

Tastes Sour Conduct Electricity Corrosive, which means

they break down certain substances. Many acids can corrode fabric, skin, and paper

Some acids react strongly with metals

Turns blue litmus paper red pH below 7

Picture from BBC Revision Bites http://www.bbc.co.uk/schools/ks3bitesize/science/chemistry/acids_bases_1.shtml

List the general characteristics of acids and bases.

Some Common Uses of Acids Acetic Acid = Vinegar Citric Acid = lemons, limes, & oranges. It

is in many sour candies such as lemonhead & sour patch.

Ascorbic acid = Vitamin C which your body needs to function.

Sulfuric acid is used in the production of fertilizers, steel, paints, and plastics.

Lactic acid is also produced by bacteria in milk – this is why milk turns sour.

Insects such as millipedes, scorpions, and ants use acids to deter predators.

Naming AcidsChemical Formula

Chemical NameBinary Acids• Named by

anion• Starts with

hydro-• Anion name

ending in –ic• Add the word

acid

HCl Hydrochloric Acid

HF Hydrofluoric Acid

H2S Hydrosulfuric Acid

HBr Hydrobromic Acid

H3P Hydrophosphoric Acid

HI Hydroiodic Acid

Name common binary acids and oxyacids given their chemical formulas

Naming AcidsOxyacids

• These acids contain polyatomic ions (and therefore usually contain O atoms)

• Based on the polyatomic anion bonded to hydrogen

• If polyatomic ion is –ite then acid is –ous• If polyatomic ion is –ate then acid is -ic

Name common binary acids and oxyacids given their chemical formulas

Naming AcidsChemical Formula

Polyatomic Ion Name of Acid

HNO2 Nitrite

HNO3Nitrate

H2SO4 Sufate

H3PO4Phosphate

H2SO3Sulfite

H2CO3Carbonate

Nitrous Acid

Nitric Acid

Sulfuric Acid

Phosphoric Acid

Sulfurous Acid

Carbonic Acid

Name common binary acids and oxyacids given their chemical formulas

What is a base?

A base is a solution that has an excess of OH- ions.

Chemists sometimes use the term “alkali” for a base that is soluble in water.

Alkali is of Arabic origin meaning “ashes of a plant.”

Bases are substances that can accept hydrogen ions, H+ (proton acceptors)

Define acid and base according to Bronsted-Lowry theory

Properties of Bases

Feel Slippery Taste Bitter Corrosive Can conduct electricity. (Think

alkaline batteries.) Do not react with metals. Turns red litmus paper blue. pH above 7

List the general characteristics of acids and bases.

Some Common Uses of Bases Bases give soaps, ammonia, and many

other cleaning products some of their useful properties.

The OH- ions interact strongly with certain substances, such as dirt and grease.

Chalk and oven cleaner are examples of familiar products that contain bases.

Your blood is a basic solution. Quinine is base used as a drug to treat

malaria. Lidocaine, a local anesthetic used by

dentists, is a base. Like acids, some bases are harmless

while others are very dangerous.

Solutions Most acids and bases

dissolve in water. A solution is a

homogenous mixture of 2 or more substances

The solute is the substance(s) present in the smaller amount(s)

The solvent is the substance present in the larger amount

Define the terms solute, solvent, solution, solubility and molarity

Solutions How well a solute dissolves in a solvent is called

solubility. We used the solubility table to determine if a

precipitate formed in a chemical reaction. Acids and bases are soluble in water The properties of acids and bases are only

exhibited when they are in solution Many factors affect solubility such as pressure,

amount of solute, amount of solvent, and temperature. (think about making Kool-Aid)

Define the terms solute, solvent, solution, solubility and molarity

Molarity Molarity (M) is a measure of

the concentration of a solution.

Concentration – how much solute in comparison to how much solvent

Define the terms solute, solvent, solution, solubility and molarity

CALCULATING MOLARITY1. Calculate moles of solute2. Convert units of solution to liters3. Use molarity formula

Calculate molarity

CALCULATING MOLARITY1. Calculate moles of solute2. Convert units of solution to

liters3. Use molarity formula

12.6 g of NaCl are dissolved in water making 344mL of solution. Calculate the molar concentration.

12.6 g NaCl 58.443 g NaCl 1 mol NaCl

= 0.216 mol NaCl

344 mL sol’n

1000 mL

1 L= 0.344 L sol’n

𝑴=𝒎𝒐𝒍𝑳 ¿

𝟎 .𝟐𝟏𝟔𝒎𝒐𝒍𝟎 .𝟑𝟒𝟒 𝑳 ¿𝟎 .𝟔𝟐𝟖𝑴

Calculate molarity

CALCULATING MOLARITY1. Calculate moles of solute2. Convert units of solution to

liters3. Use molarity formula

46.8 g NaHCO3

84.006 g NaHCO3

1 mol NaHCO3 = 0.557 mol NaHCO3

350 mL sol’n

1000 mL

1 L= 0.35 L sol’n

𝑴=𝒎𝒐𝒍𝑳 ¿

𝟎 .𝟓𝟓𝟕𝒎𝒐𝒍𝟎 .𝟑𝟓𝑳 ¿𝟏 .𝟔𝑴

What is the molarity of 350 mL of a solution containing 46.8 g of NaHCO3?

Calculate molarity

CALCULATING MOLARITY1. Calculate moles of solute2. Convert units of solution to

liters3. Use molarity formula

0.313 mol LiOH 23.948 g LiOH

1 mol LiOH = 7.50 g LiOH

250.0 mL sol’n

1000 mL

1 L= 0.2500 L sol’n

𝑴=𝒎𝒐𝒍𝑳

𝟏 .𝟐𝟓=𝒙𝒎𝒐𝒍

𝟎 .𝟐𝟓𝟎𝟎𝑳𝒙=𝟎 .𝟑𝟏𝟑𝒎𝒐𝒍

How many grams of LiOH is needed to prepare 250.0 mL of a 1.25 M solution?

Calculate molarity

CALCULATING MOLARITY1. Calculate moles of solute2. Convert units of solution to

liters3. Use molarity formula

0.35 L 1000 mL

1 L= 350 mL solution

25 g H3PO4

97.994 g H3PO4

1 mol H3PO4 = 0.26 mol H3PO4

𝑴=𝒎𝒐𝒍𝑳 𝟎 .𝟕𝟓𝐌=

𝟎 .𝟐𝟔𝒎𝒐𝒍𝒙 𝑳

𝒙=𝟎 .𝟑𝟓𝑳

What volume of solution will contain 25 g of H3PO4 if the solution concentration is 0.75 M?

Calculate molarity