Quiz #5: Chemical Compounds
How to balance a chemical equation
- Balance elements that occur in only one compound on each side first. - Balance free elements last. - Balance unchanged polyatomic ions (or other groups of atoms) as groups. - Fractional coefficients are sometimes acceptable but should be cleared at the end by multiplication. - Check: numbers of all atoms are consistent on reactant and product sides of equation both sides of the equation have the same total charge
Naming binary compounds between 2 nonmetals (covalently bonded)
- Element with OS>0 (first element in the formula) is named first. - Second element is named as if it were an anion. - Use prefixes when more than one atom of a given element unless it would be redundant eg. HCl → hydrogen chloride
Naming hydrates
- name the compound as appropriate, then add hydrated waters to the name - it is important to distinguish between the anhydrous and hydrated forms of the compound eg. CuSO4 → anhydrous copper(II) sulfate eg. CuSO4·5H2O → copper(II) sulfate pentahydrate
Naming acids
- when dissolved in water, acids produce free H+ - acid name depends on presence of oxygen
Prefixes for compounds
1- mono (or nothing) 2- di 3- tri 4- tetra 5- penta 6- hexa
Order of oxyanion prefixes/suffixes from oxidation states
GREATEST per ... ate ate ite hypo ... ite LEAST addition of an oxygen = greater
An ionic compound is probably an acid if
It begins with H
-COOH signifies
an acid
-OH signifies
an alcohol, fuel
Naming binary ionic compounds where metal has only one oxidation state
cation (metal) first, then anion (nonmetal) ex: cation (metal) ≡ name of the element eg. Ca2+ ≡ calcium anion (nonmetal) ≡ root + -ide eg. Cl− ≡ chloride → CaCl2 ≡ calcium chloride
Naming binary ionic compounds where metal has more than one possible oxidation state (transition metal)
cation ≡ element name (Oxidation state) eg. CuCl → copper(I) chloride eg. CuCl2 → copper(II) chloride
Symbols for states of reactants and products
g ≡ gas, l ≡ liquid, s ≡ solid, aq ≡ aqueous solution aqueous solution ≡ dissolved in water
Rules for naming acids
if no oxygen in anion: prefix "hydro-" and suffix "-ic" eg. HCl ≡ hydrochloric acid, H2S ≡ hydrosulfuric acid if anion contains oxygen: use root name of anion with suffix "-ic" if the anion ends in "-ate" H2SO4 ≡ sulfuric acid (sulfate anion) HNO3 ≡ nitric acid (nitrate anion) use root name of anion with suffix "-ous" if the anion ends in "-ite" H2SO3 ≡ sulfurous acid (sulfite anion) HNO2 ≡ nitrous acid (nitrite anion)
Naming Polyatomic Ions
oxoanions are named in the order of the oxidation state of the nonmetal atom to which O is bonded hypo-...-ite < ...-ite < ...-ate < per-...-ate ClO-, ClO2-, ClO3-, ClO4- (hypochlorite, chlorite, chlorate, perchlorate) oxoanions with different numbers of H are named as such HPO42- (hydrogen phosphate ion) H2PO4- (dihydrogen phosphate ion) the prefix "thio-" indicates that an oxygen atom has been replaced by a S atom SO42- (sulfate) S2O32- (thiosulfate)
stoichiometric factor
ratios of stoichiometric coefficients
How to write a chemical equation
represent chemical change by a chemical equation: reactants → products eg. CH4 + O2 → CO2 + H2O physical states of reactants and products should be given: eg. CH4(g) + O2(g) → CO2(g) + H2O(l)
Under normal temperatures, ionic compounds are
solid
Reaction conditions
some reaction conditions: Δ ≡ heat hν ≡ light actual temperature for reaction pressure conditions (eg. 10 atm) catalysts (eg. metal surface, etc.) acid or base
Before you name a covalent bond, always check
that it is in EMPIRICAL FORMULA
Exceptions for covalent compound names
when prefix ends in a or o and element starts with a or o...