Chemistry Notes PDF

1. Unit Conversions Cminding +1000") - Mass (mg, g, kg) mg --- :1000 ---> g --- :1000 ---> kg - Volume (cm³, dm³, m³) cm³ --- :1000 ---> dm³ --- :1000 ---> m³ - Amount of substance (mmol, mol) mmol --- :1000 ---> mol - Density (g/cm³, kg/m³) g/cm³...

1. Unit Conversions Cminding +1000") - Mass (mg, g, kg) mg --- :1000 ---> g --- :1000 ---> kg - Volume (cm³, dm³, m³) cm³ --- :1000 ---> dm³ --- :1000 ---> m³ - Amount of substance (mmol, mol) mmol --- :1000 ---> mol - Density (g/cm³, kg/m³) g/cm³ --- x1000 ---> kg/m³ - Pressure (MPa, kPa, Pa) MPa --- :1000 ---> kPa --- :1000 ---> Pa  2. Simple Calculation Tasks (Calculate one quantity from given data) - Mass percentage/mass fraction m mea x = in - mass fraction n(substance) / (n(substance) + Mn(water) X = moat M OS2 -m mo mass percentage m/m% = x x 100 ~ Im % = t x most 100 u ~ mo - Molar percentage/molar fraction mod - W molar fraction w = m(substance) / (n(water) = Nost molar percentage n/n% = w x 100 /n % = noS[ x 100 - Amount concentration Noa - amount concentration c = n(substance) / n(solution) 2 = No - Density density (g/cm3) ρ = m(substance) / V(solution) S = - Mass concentration mass conc. (g/dm3) γ= m(substance) / V(solution) U(cm) = - Use of mixing equation 1. How many grams of solute are in 450 g of a 25% (w/w) solution? m(solution) = 450 g mo = 450g 25 = 50.100 m/m = 25 % m/m% = 0.25 1125 = 10x Moa = X = - 112 , 5g m(solute) = 450 g x 0.25 = 112,5 g 2. The density of a substance is 1.45 kg/dm³. What is the mass in grams of 250 cm³ of this 25 am 453g/dm3V 0 substance? = , S = 1, V = 250cm3 m = V. S x 1000 ρ(substance)= 1.45 kg/dm³ - 3625bg = 02 59 1 , 45 x 0, 25 0, = , m = - m = ? V(substance) = 250 cm³ = 0.25 dm3 m(substance) = 1.45 kg/dm³ x 0.25 dm3 = 0,3625 kg = 362,5 g 3. The density of a substance is 1.45 kg/dm³. What is the volume in cm³ of 250 g of this 25 substance? by 0. g/dm > m = 9 = 1145 m = 250g V = m - * 100 ρ(substance)= 1.45 kg/dm³ 1724dm s v = ? V = = 0, = = 172 m(substance) = 250 g = 0.25 kg V(substance) = 0,25 kg / 1.45 kg/dm³ = 0,1724 dm3 = 172,4 cm3  3. Formulas of Inorganic Compounds - Write the formula for a compound composed of the given ions: nitrite NO2- iron (II) Fe2+ nitrate NO3- iron (III) Fe3+ carbonate CO32- ammonium NH4+ hydrogen carbonate HCO3- lead (II) Pb2+ sulphide S2- magnesium Mg2+ sulphite SO32- silver (I) Ag+ sulphate SO42- copper (II) Cu2+ oxide O2- sodium Na+ hydroxide OH- potassium K+ chloride Cl- aluminium Al3+ nincs kedvem kiírni az összes formulát amit ezekből lehet:)  4. Inorganic Chemistry - Provide formulas and names for three chlorine-containing disinfectants. 1. NaOCl sodium-hypochlorite / bleach 2. Ca(OCl)2 calcium-hypochlorite / chlorinated lime 3. HOCl hypo - Provide formulas and names for three chlorine-free disinfectants. 1. I2 iodine 2. O3 ozone 3. H2O2 hydrogen-peroxide - Identify ions causing water hardness. Mg2+, Ca2+ - Explain the term “heavy water.” water that has a high Mg- and Ca-salt content - List the components of bleach (with formula). NaOCl, H2O - Provide the formula for chlorinated lime Ca(OCl)2 - Write the structural formulas for the conversion of orthophosphoric acid to diphosphoric acid. P4O10 + 6 H2O = 4 H3PO4 H3PO4 + HPO3 = H4P2O7 - Draw the formulas and names for two gas neurotransmitters. NO nitrogen-oxide (gas) N O N2O dinitrogen-oxide (gas) N N O - Draw the formulas for the two oxides of carbon and provide their names. CO carbon-monoxide (gas) C O CO2 carbon-dioxide (gas) O C O - Provide formulas, names, and states for two carbon-containing, highly toxic inorganic compounds. CO carbon-monoxide (gas) C O HCN hydrogen-cyanide (liquid) H C N - Explain the components of a metal complex. a central cation or anion and ligands - cation: a positively charged atom/molecule - anion: a negatively charged atom/molecule - ligand: an atom/molecule with a lone pair of electrons which can donate the electron pair to form a coordinate bond with a central metal atom - Describe the parts of metal complexes based on Lewis acid-base theory. Lewis-bases: molecules or anions, that have lone electron pair with which it can form covalent, dative bonds Lewis-acids: molecules or cations that can form a covalent, dative bond by accepting a lone electron pair from a base - Define the term “chelate complex.” a compound that has two or more coordinate or dative bonds between a ligand and a central metal atom - Define the term “macrocyclic chelate.” large, cyclic ligands with three or more donor sites  5. States of Matter - Explain how the boiling point of a liquid depends on external pressure. the greater the pressure, the more energy required for liquids to boil, and the higher the boiling point - Define equilibrium vapor pressure. the pressure exerted by a vapor that is in equilibrium with the condensed phase (solid or liquid) at a given temperature in a closed system - Identify factors influencing the solubility of a gas in liquids. 1. temperature 2. pressure 3. nature of the solute and the solvent - Define osmosis. the solvent flows through the membrane to equalize the solute concentration on both sides of the membrane - Define osmotic pressure. equals to the pressure that when applied to the solution just stops osmosis - Explain what an isotonic solution is. the state when two solutions have equal concentration of solutes across a semipermeable membrane - Explain what a hypertonic solution is. a type of solution that has a higher concentration of solutes on the outside of a cell than on the inside of the cell - Explain what a hypotonic solution is. a type of solution that has a lower concentration of solutes on the outside of a cell than on the inside of the cell  6. Kinetics - Define reaction rate. the measure of the change in concentration of the reactants or the change in concentration of the products per unit time - List three factors influencing reaction rate. 1. temperature 2. pressure 3. concentration - Explain the concept of half-life in a chemical reaction. the time required for the concentration of the reactant to decrease to halfway between its initial and final values - Define catalysis. a substance that increases the rate of a chemical reaction by opening a new path by which the reaction can take place or by lowering the energy of activation - Explain the concept of inhibition. a substance that decreases the activity of a catalyst by blocking its “active site”  7. Electrolysis - Define electrolysis. process by which electric current is passed through a substance to effect a chemical change - the substance loses (oxidation) or gains (reduction) an electron - Explain the basic operation of galvanic cells. a cell that uses a chemical redox-reaction to produce electrical energy anode: the negative electrode cathode: the positive electrode - produces e- by the oxidation - uses the e- for reduction the electrons flow through the external wire from the anode to the cathode cations - move through the salt bridge from the anode solution to the cathode solution anions - move through the salt bridge from the cathode solution to the anode solution - Define oxidation and reduction. oxidation: the loss of electrons during a reaction reduction: the gaining of electrons during a reaction - Define the components of the combined electrode used in pH measurements. glass electrode - depends on the concentration of H+ reference electrode - known constant (the galvanic cell has to be calibrated with a known buffer solution) - Define metal corrosion. the process whereby metals are oxidized to their oxides and sulphides - Explain when a local cell is formed. a galvanic cell that is formed due to physical or chemical differences between areas on a metal surface in an electrolyte  8. Equilibria - Write the mass action law for a given equilibrium reaction. (e.g. N2 + 3 H2 ⇌ 2 NH3) Kc = [NH3]2 / ([N2] x [H2]3) - State Le Chatelier-Braun principle. a system in equilibrium reacts to a change in conditions in a way that counteracts the applied change and establishes a new equilibrium - Define acids according to Arrhenius theory. a compound that produces H+-ions in water - Define bases according to Arrhenius theory. a compound that produces OH--ions in water - Define acids according to Brönsted-Lowry theory. a compound that can donate protons (proton donor) - Define bases according to Brönsted-Lowry theory. a compound that can accept protons (proton acceptor) - Write the ion product of water. What concentrations does it represent at 25 °C for hydronium- ions and hydroxide-ions? ionic product of water - from the self-dissociation constant of water 2 H2O ⇌ H3O+ + OH- K = ([H3O+] x [OH-]) / [H2O]2 K x [H2O]2 = [H3O+] x [OH-] simplified form: Kw = [H3O+] x [OH-] = (1.0 x 10-7) x (1.0 x 10-7) = 1.0 x 10-14 - Write the definition of pH with a formula and interpret the symbols in the formula. pH = -log [H+] negative decadic logarithm of [H+] in mol/dm3 - Write the definition of pOH with a formula and interpret the symbols in the formula. pOH = -log [OH-] negative decadic logarithm of [OH-] in mol/dm3 - Explain the term “weak acid” in chemistry. an acid that partially dissociates into its ions in an aqueous solution or water - Explain the term “strong acid” in chemistry. an acid that completely dissociates into its ions in an aqueous solution or water - Explain the use of buffer solutions. a solution capable of maintaining its pH at nearly constant value even when small amounts of strong acid/base are added - List the components of an acidic buffer solution. weak acid and its salt - List the components of a basic buffer solution. weak base and its salt - Explain the term “hydrolyzing salt.” a process that occurs when salt is mixed into the water and the water breaks the ionic bond, resulting in either acidic or basic aqueous solutions - Provide three examples of weak acids. 1. acetic acid CH3COOH 2. formic acid HCOOH 3. phosphoric acid H3PO4 - Provide three examples of strong acids. 1. hydrochloric acid HCl 2. sulfuric acid H2SO4 3. nitric acid HNO3 - Provide two examples of strong bases. 1. sodium-hydroxide NaOH 2. potassium-hydroxide KOH 3. calcium-hydroxide Ca(OH)2 - Provide two examples of weak bases. 1. ammonia NH3 2. lead(II)-hydroxide Pb(OH)2 3. magnesium-hydroxide Mg(OH)2  9. Colloids - Define colloidal systems. mixture of two substances, a dispersed phase and a dispersion medium in which the dispersed substance’s particle size is between 1nm - 500nm - Explain what is meant by emulsion. a mixture of two or more liquids that are normally immiscible - liquid-liquid phase separation - Explain what is meant by suspension. a heterogeneous mixture of a finely distributed solid in a liquid - Define adsorption. change in the concentration of a substance at a phase interface - Explain the concept of hydration in chemistry. a chemical reaction in which a substance combines with water - a stabilizing factor in keeping molecules of proteins in a dissolved state  10. Miscellaneous - Define chemical compound. the result of the combination of atoms that contains the same kind of atoms combined in the same proportions - Define the term "isotope." atoms whose nuclei have the same atomic number (same number of protons), but different mass number (different number of neutrons) - How would you define valence electrons? electrons in the outermost shell of an atom that can participate in the formation of a chemical bond - if the shell is not closed - Name the molecules in which hydrogen bonding can occur (mention three conditions) molecules in which F / O / N (highly electronegative) atoms covalently bond with H atoms - Explain what an exothermic process is. any process that gives off heat - transfers thermal energy to its surroundings - Explain what an endothermic process is. any process that has to be supplied with heat by its surroundings - Define the heat of combustion. heat produced when a substance is combusted in excess of oxygen (completely oxidized)