Unit 7: Acids

+1 +2 +3 +/-? -3 -2 -1 +? THESE CAN HAVE VARIABLE CHARGES +2 +1 +2

Common Polyatomic Ions

Acids Nomenclature

What is an acid? Many definitions of what acids are for our purpose this unit, we will use Arrhenius’s definition: an acid is a substance that produces hydrogen ions (H+1) in solution If all acids produce hydrogen ions in solution, what must all acids have? What is a H+1? This is why sometimes acids are called proton donors (an H+1 is a proton) Acids will be discussed in much greater detail next semester, for this unit, we are going to learn what acids are, properties, and how to name them

Bases and Salts Many definitions of what bases are for our purpose this unit, we will use Arrhenius’s definition: a base is a substance that produces hydroxide ions (OH-1) in solution If all bases produce hydroxide ions in solution, what must all bases have? Salts: ionic compounds that produce neither hydrogen nor hydroxide ions when dissolved in water (i.e. an ionic compound with out H+ or OH-) When an acid and a base react, they always produce a salt and water

Properties of Acids pH < 7 Produce hydrogen ion in water Taste sour React with metals to produce hydrogen gas They are electrolytes (meaning they conduct electricity when dissolved in water) Turn indicators different colors Indicators are paper or solutions that change color based on properties of the substance being tested React with bases to produce salt and water

Properties of Bases pH > 7 Produce hydroxide ion in water Taste bitter and feel slippery They are electrolytes (meaning they conduct electricity when dissolved in water) Turn indicators different colors React with acids to produce salt and water

Rules for Naming Acids Binary acids are made up of 2 elements (one being hydrogen) The acid is named with the prefix hydro- and the suffix –ic attached to the root name for the element. Then the word acid is added to the end. Hydro______________ic acid HCN is the only ternary acid named like a binary acid (Hydrocyanic acid) Example: HCl is hydrochloric acid What is HBr?

Rules for naming acids Ternary acids contain 3 or more elements (one being hydrogen and the others are part of a polyatomic ion) Named with a suffix –ic or –ous. When the anion names in –ate, the suffix –ic is used. When the anion name ends in –ite, the suffix –ous is used in the acid name. Then the word acid is added to the end. Ate  ic acid Ite  ous acid HCN is the only ternary acid named like a binary acid (Hydrocyanic acid) H2SO4 the anion is sulfate ate  ic; Sulfuric acid H2SO3 the anion sulfite ite  ous; Sulfurous acid What is the name of H3PO4? What is the name of H3PO3?

Examples Name the following acids: HCN: H2S: HC2H3O2: HNO2: H2O: It is ternary, but we name it as binary, so we give it the prefix hydro and the suffix ic  hydrocyanic acid H2S: It is binary, so we give it the prefix hydro and the suffix ic  hydrosulfuric acid HC2H3O2: It is ternary, the anion is acetate, so we add the suffix ic  Acetic acid HNO2: It is ternary, the anion is nitrite, so we add the suffix ous  Nitrous acid H2O:

Name the Following Acids HClO4 HClO3 HClO2 HClO HI HNO3

Writing Formula From Name The acid contains Hydrogen cation and an anion. Determine the anion. Look at the prefixes and suffixes of the acid’s name to determine the anion Write the formula in the following format: H#A H then the charge of the anion as a subscript (no – sign) and then the anion Write the formula unit for the following acids: Hydrophosphoric acid, phosphoric acid, and phosphorous acid H3P H3PO4 H3PO3

Molar Mass A mole is a specific quantity of something Similar to a dozen or a pair A mole is 6.02 x 1023 of something A dozen eggs is 12; a dozen donuts is 12; a dozen molecules is 12 A pair of eggs is 2; a pair of donuts is 2; a pair of molecuels is 2 A mole eggs is 6.02 x 1023 ; a mole of donuts is 6.02 x 1023 ; a mole of molecules is 6.02 x 1023 Molar mass is the mass of 1 mole of the substance or the mass of 6.02 x 1023 compounds of the substance Different than atomic mass because atomic mass is the mass of one atom or compound in units of amu; where molar mass is the mass of a mole (or a large amount) of compounds in units of g/mol Units are grams per mole or g/mol Round to 2 decimal places Molar mass of each element is on the periodic table

Finding the Molar Mass For Sulfurous Acid = H2SO3 Molar mass of each element is on the periodic table Hydrochloric acid: HCl Contains 1 H atom and 1 Cl atom 1 H = 1.01g/mol H 1 Cl = 35.45g/mol Cl So add the mass of the H plus the Cl 1 HCl = 36.46g/mol HCl For Sulfurous Acid = H2SO3 Contains 2 H atoms 1 S atom and 3 oxygen atoms 2 H = 2(1.01g/mol) = 2.02 g/mol of H 3 O = 3(16.00g/mol) = 48.00 g/mol O 1 S = 32.07 g/mol S Add them up 1 H2SO3 = 82.09 g/mol of H2SO3

Determine the Molar Mass for the Following 1) HBr 2) H3PO4 3) Al2(SO4)3 (remember the subscript 3 is distributed to the S and the O, so you have 3 S and 12 O)

ANSWERS HBr 1.01 + 79.90 = 80.91 g/mol 2) H3PO4 3) Al2(SO4)3 (remember the subscript 3 is distributed to the S and the O, so you have 3 S and 12 O) 2(26.98) + 3(32.07) + 12(16.00) = 222.17g/mol