Section 3- Part 1

chrome plating

1. most common example of electroplating 2. it's used to create shiny parts on appliances and automobiles

phlogiston theory

1. the faulty theory proposed that as materials burned, they released a substance- termed phlogiston- that couldn't be detected 2. highly combustible materials were thought to contain much phlogiston while less combustible materials were thought to contain very little

buret

1. the long tube that has a device called a stopcock that opens and closes, allowing for the solution to be added by drops into the Erlenmeyer flask. 2. it allows for accurately measured volumes of a liquid to be introduced

anion

A negatively charged ion

cation

A positively charged ion

anion examples of pH = 7

Cl-, Br-, I-, ClO4-, BrO4-, NO3-

bases

Compounds that reduce the concentration of hydrogen ions in a solution.

anion examples of pH > 7

F-, HCO3-, SO42-, CH3COO-

cation examples of pH < 7

NH4+, CH3NH3+, Cu2+

cation examples of pH = 7

Na+, K+, Rb+, Cs+, Mg2+, Ca2+

voltage

The potential difference measured in volts. The amount of work to be done to move a charge from one point to another along an electric circuit.

Johann Baptista van Helmont

a Belgian physician who had a noted interest in medical chemistry and believed that if he could better understand chemistry, he would better understand the causes of disease

pH indicator

a compound that has different color at different pH to indicate the equivalence point. it changes color when the reaction reaches the endpoint

activity series

a list of elements organized according to the ease with which the elements undergo certain chemical reactions

electroplating

an electrolytic process in which a metal ion is reduced and a solid metal is deposited on a surface

base

any substance that accepts H+ ions. many have an OH- ion

particulate matter

atmospheric particles that enter the lungs where they can stick or exchange harmful components that damage lung tissue

galvanic electrochemical cell

composed of two half cells, each involving an electrode, in contact with a solution containing metal ions

acids

compounds that form hydrogen ions when dissolved in water

neutral salt

dissolving sodium chloride in water; sodium and chloride ions are produced. neither reacts appreciably with water in an acid-base hydrolysis reaction, so the pH = 7, and hence it's a neutral solution: Na+ (aq) + Cl- (aq) + H2O (l) >> no reaction neutral salts are formed from the cation of a strong base and the anion of a strong acid

acidic salt

dissolving solid ammonium chloride in water; ammonium and chloride ions are formed. the ammonium ion donates a proton to water, forming the hydronium ion: NH4+ (aq) + H2O (l) >> NH3 (aq) + H3O+ (aq) 1. the conjugate base produced, ammonia, is a weak base that don'ts ionize to any great extent. since the ammonium ion has donated a proton to water, it has behaved as an acid. 2. the solution will have a pH < 7 as a result of the hydronium ions produced 3. the chloride ions are spectators. 4. in general, cations of weak bases will form acidic salts

basic salt

dissolving solid sodium acetate in water; sodium and acetate ions are formed. the acetate ion (an anion) accepts a proton from water, forming excess hydroxide ion: CH3COO- (aq) + H2O (l) >> CH3COOH (aq) + OH- (aq) 1. the conjugate acid produced, acetic acid, is a weak acid that doesn't ionize to a great extent. since the acetate ion has accepted a proton, it has behaved as a base. 2. the solution will have a pH > 7 as a result of the hydroxide ions produced. the sodium ions are "spectators" 3. in general, anions of weak acids will form basic salts

single replacement reaction

have one atom moving into a compound and another atom moving out of the compound

in water solutions, the hydrogen atom is transferred to water as a positive ion, H+

how are hydrogen atoms transferred?

it's a negative number

how can we tell if a reaction is non-spontaneous based on the voltage?

it's a positive number

how can we tell if a reaction is spontaneous based on the voltage?

1. he heated mercury calx, causing it to decompose into mercury and a gas. 2. he noted that the combined masses of the mercury and the gas were the same as the original mass of the calx prior to burning 3. he conducted a reverse experiment in which he heated the mercury and the gas and found that it yielded mercury calx of the same mass. it was significant that the total mass remained constant because that conclusion countered the notion that the substance was releasing phlogiston

how did Antoine Lavoisier develop a scientific explanation for combustion that refuted phlogiston theory?

1. in an experiment, he heated mercury in a specific volume of air to create mercury calx and observe that this decreased the volume of the air 2. he then put a lit candle into the container of air and saw that the candle's flame was extinguished. this indicated to him that the gas that had been mixed with the mercury was required for combustion. 3. this gas was called oxygen and referred to metal calves as metal oxides

how did Lavoisier explore that idea that when metals formed a calx, they combined with a gas that was in the surrounding air?

he established that mass is neither created nor destroyed during a chemical reaction, as was made clear by the fact that the mass of the reactants was equal to the mass of the products in his experiments with mercury calc.

how did Lavoisier's experiments lead to the principle of conservation of mass?

if the cation reacts significantly with water to form the conjugate base and H+

how do we know a solution is acidic from hydrolysis?

if the results in the anion of the salt reacting with water produces the conjugate acid of the anion and the hydroxide ion

how do we know a solution is basic from hydrolysis?

if neither ion reacts significantly or if both react equally

how do we know if a solution is natural based on hydrolysis?

1. at low pH, OH- concentration is low and increases as the pH increases 2. as OH- increases further, it reacts with the metal hydroxide to form a soluble oxide ion

how does the precipitation of metal hydroxide depend on the concentration of OH-?

1. a given amount of acid with an unknown molarity is placed into a flask, and a solution of a base of unknown molarity is added by using a buret 2. the acid is in the flask, and the base is in the buret

how does titration work?

1. he created a more coherent picture of what the "rules" of chemistry are and made numerous influential findings that have held true over the course of time 2. he discovered that air is composed primarily of oxygen and nitrogen; that water can't be converted into Earth; and that matter is conserved in chemical and physical interactions 3. he began to systemize the naming of chemical compounds, and his system of chemical nomenclature continues to be used by scientists in the present day

how is Lavoisier the "father of modern chemistry"?

it enters the environment as metallic mercury emitted into the atmosphere from fossil fuel power plants and enters lakes and soils as waste from the use of mercury in electrolytic cells fro the production of chemicals, such as chlorine

how is mercury the most well-known containment?

1. unless nutrients dissolve, they're unavailable to plants, and so farmers must add acidic or basic substances to their soils to optimize the dissolution of nutrients 2. in some regions acid rain is responsible for lowering soil pH. this must be balanced by the addition of basic chemicals to neutralize the effects of the acid rain 3. efforts to adjust soil pH may inhibit efforts to remove toxic contaminants that have been added to the environment by increasing their solubility

how is the control of soil pH an example of how precipitation has significant environmental ramifications?

it can either be an acid or a base

how is water amphoteric?

when acetic acid is added to water to make vinegar, the reaction that occurs is: HC2H3O2 + H2O >> H3O+ + C2H3O2- the acetic acid has transferred an H+ to water and is acting as an acid in solution. the water has acted as a base by accepting the H+ and forming a negative acetate ion. the excess of H3O+ ions make the solution acidic

in other situations, how can water behave as a base by accepting a hydrogen ion and forming H3O+ (hydronium ion)?

pH meter

instrument that measures titrations, as well as the pH state of any solution

oxidation-reduction or redox reactions

involve a transfer of electrons from one molecule to another

synthesis or combination reactions

involve combining two ore more reactants and making one product

electrochemistry

involves the use of the oxidation-reduction reactions. we want to understand what governs which reactions will occur and how this can be used

double replacement reaction

involves two ionic compounds in solution training ions

diprotic acid (H2SO4)

it can provide 2 H+ ions to the reaction for every mole of acid added

triprotic acid (H3PO4)

it can provide up to 3 H+ ions for every mole of acid added

pH scale

it's a log scale that relates the acid concentration, which is defined as the concentration of H3O+ in units of moles per liter

oxidation numbers

it's equal to the number of electrons that must be added or subtracted from the atom in its combined state to get to the number of electrons of its free, neutral atom

salt

it's the compound formed when the H+ of an acid is replaced by a metal ion or its equivalent.

being transported in mine run-off and toxic materials absorbed on iron hydroxide precipitate

many other precipitates cause problems in the environment, including those..?

pH

measure of the acidity or basicity of an aqueous solution

decomposition reaction

one reactant breaks into several products

combustion reactions

reactions fo a reactant substance with oxygen gas. if the reactant is an organic hydrocarbon, then the complete combustion products will be water and carbon dioxide

MaVa = MbVb a = total acid b = total base M = molarity of each substance V = volume of each substance

since the moles of acid and base are equal at the equivalence point, what's the equation?

Transmutation

the conversion of an atom of one element to an atom of another element

anode

the electrode where oxidation occurs

cathode

the electrode where reduction occurs

spectator ions

the ions that don't form precipitates and remain in the solution because no change occurs to them during the reaction

volts

the tendency of an electron to leave an atom or to join an atom is measured as electrical energy in this unit

acid-base reactions

they're a type of double replacement reaction where an acid + a base yields a salt + water

natural salts

those that are made from a strong acid and a strong base Ex: HCl + NaOH >> NaCl

strong acids

those that will transfer all their H+ to water

weak acids

those that will transfer only a few molecules of H+ to water

cell potential

voltage can be measured even when an actual transfer has barely taken place

he introduced the term "gas", developed an effective balance, anticipated the law of conservation of mass, and provided several refutations of the notion of alchemy and element transmutation

what advancements did Van Helmont make?

1. H and group 1 elements have oxidation numbers of +1 2. the oxidation number of O is -2 Exceptions: 1. H has an oxidation number of -1 in metal hydrides, such as AIH3 2. O has an oxidation number of -1 in peroxides, such as H2O2

what are a couple of rule to determine the oxidation numbers for different elements?

1. the oxidation number of all monoatomic ions is the charge on the ion 2. all neutral atoms have an oxidation number of 0 3. oxidation numbers of atoms in natural compounds must add up to 0 4. the sum of the oxidation numbers of atoms in polyatomic ions must be equal to the charge on the ion

what are four other rules about oxidation numbers?

1. synthesis 2. decomposition 3. double replacement 4. single replacement 5. combustion

what are the five basic types of reactions?

1. group 1 nitrates, acetates, and chlorate and ammonium ions are soluble. carbonates, hydroxides, oxides, silicates, and phosphates are insoluble 2. only Ag, Hg(I), and Pb(II) form precipitates with chloride, bromide, and iodide 3. all sulfates are soluble, except those of barium, strontium, calcium, lead (II), silver, and mercury (I). most sulfides are insoluble except for calcium, strong, magnesium, sodium, potassium, and ammonium

what are the solubility rules?

acid-base reactions, precipitation reactions, and oxidation-reduction reactions

what are three types of reactions?

1. the modern practice of operating research labs, producing more frequent publications, and encouraging the exchange of scientific ideas 2. much of their practice and discussions focused on reactions in air, as they tried to explain the results of reactions of metals and carbon compounds heated in air- reactions that are now known as "oxidation"

what did Robert Boyle, Joseph Black, Henry Cavendish, Joseph Priestley, and Antoine Lavoisier begin to do?

observation and experimentation and they pioneered the chemical processes of distillation, percolation, and extraction

what did alchemists' efforts focused on using?

M + BC ---> MC + B

what does a single replacement reaction look like if the incoming atom is a metal, M?

N + BC >> BN + C

what does a single replacement reaction look like if the starting element is nonmetal, N?

1. a solution with a low pH has a lot of H+ compared to pure water 2. a high pH solution has very little H+

what does it mean when a solution has a low pH and high pH?

Pb, Sn, Ni, Co

what elements can displace hydrogen from acid?

Cd, Fe, Cr, Zn, Mn, Al, Mg

what elements can displace hydrogen from steam?

Na, Ca, Ba, K, Li

what elements can displace hydrogen from water?

Cu, Hg, Ag, Au

what elements can't displace from any source?

substances whose formulas start with atoms of hydrogen: Hal, HBr, H2SO4, HC2H3O2, and HNO3-

what formulas do most acids have?

two solutions, each containing ions in water, are mixed, and one of the products will be a solid precipitate that forms in the solution, often appearing as a cloud. the precipitate may settle slowly to the bottom of the container

what happens in a precipitation reaction?

pH = -log[H3O+], where the square brackets indicate concentration in the units of molarity. chemists usually abbreviate [H3O+] to simply [H+]

what is the equation for pH?

1. an acid is defined as any reactant that donates an H+ in a reaction, and a base is defined as any H+ acceptor in the reaction 2. this could explain the behavior of NH3, in water. in the reaction NH3 + H2O >> NH4+ + OH-, the water donates an H+ to the ammonia, making water an acid and ammonia a base. Ammonia becomes a positive ammonium ion, and the other product is OH-. the solution has an excess of OH- ions and thus is basic 3. it also explains all Arrhenius acids and bases

what theory did Danish chemist Johannes Bronsted and British chemist Thomas Martin Lowry propose about acids and bases?

1. acids break apart in water to yield hydrogen ion and that bases break apart in water to yield hydroxide ions 2. the theory was incomplete because it couldn't explain why, for example, tests would show that ammonia solution was basic despite the fact that ammonia doesn't contain hydroxide

what theory did Swedish scientist Svante Arrhenius propose concerning acids and bases?

1. before digital cell phone cameras became so widely used, an enormous number of photographs were processed 2. almost all of these involved the use of silver halide salts. after the exposure and development of the image, which consisted of silver metal on paper or plastic, excess silver had to be removed in a process called fixing 3. large amounts of silver in the waste solutions were then completed with the chemical sodium thiosulfate 4. the silver could be precipitated as metallic silver by adding iron (steel wool) or as silver chloride by adding chloride ion 5. the silver could be melted into ingots, or the chloride could be dissolved in nitric acid, and the silver could be electrolytically plated

what's the process for the recovery of silver metal from used photographic chemicals?

it's above 7, which indicates that [H+] is smaller than 1.0 * 10^-7 M.

what's the value of a basic substance?

it's below 7, which indicates that [H+] is greater than 1.0 * 10^-7 M

what's the value of an acidic substance?

titration

when acids and bases are mixed together and the pH is measured as different amounts react

when atoms in chemical substances rearrange under certain conditions to form new substances that have different physical and chemical properties

when do reactions occur?

equivalence point or endpoint

when the moles of acid in the flaks are exactly equal to the moles of added base. it can be identified with a pH indicator

hydrolysis

when the salt dissolves in water, its ions can interact with water molecules in a reaction

they were at first challenged by leading physicians but were supported and followed closely by an expanding group of non-medical scientists working in France and Britain, notably Robert Boyle, Joseph Black, Henry Cavendish, Joseph Priestley, and Antoine Lavoisier

who supported and challenged Van Helmont's ideas?