Ch 8 SG

Aunt Valeries

Au, V, Fe, Sn, Cr, Pb, Cu, Co - watch out for when you have to name it so you put the charge in ( )

Co, Ni, Sn, Pb

DO NOT react w/ water - react with acids replacing the hydrogen - react with oxygen forming oxides

Synthesis reaction--oxides/sulfide

Element (almost all metals) +Oxygen = Oxide Element (almost all metals) +Sulfur = sulfides Group 1 and 2 (active metals) react the most with oxygen and sulfur-- M₂X or MX Ex: 2Mg (s) + O₂→2MgO magnesium reacts with oxygen to produce magnesium oxide

Displacement of halogens

Halogen replaces another halogen (g17) in a compound - CATIONS being replaced - e/a halogen is less reactive than the one above it -- e/a element can replace any element below it but NOT any element above it - F is the most reactive can replace any of the other halogens Cl₂ (g) + KBr (aq)→Br₂ (g) + KCL (aq)-- chlorine more reactive than bromine Br₂ (S) + KF (aq)→No Reaction Fluorine is more reactive than bromine so can't replace

HOF BrNCl-- diatomic elemets

Hydrogen Oxygen Fluorine Bromine Iodine Nitrogen Chlorine written with two subscript bc too reactive to exist by themselves

Reactants and products

In chemical reactions Reactants-- og substances Products--resulting substances

activity series of the elements

ONLY FOR SINGLE REPLACEMENT REACTIONS list of elements organized according to the ease w/ which the elements undergo certain chemical reactions-- in order of reactivity highest most reactive to lowest least reactive - based on experiments of single-displacement reactions - helps predict if chemical reaction takes place - most active element on top can replace any element below it-- element further down can't replace any element above it (halogens are in order) for metals: greater activity-- grater ease of loss of electrons (cations) for nonmetals: greater activity-- greater ease of gain of electrons (anions)

Synthesis reaction-- with oxides of active metals

Oxides of active metals (g1,2) react with water to produce metal hydroxides (M(OH)) Ex: CaO (s) + H₂O →Ca(OH)₂ AB calcium oxide reacts with water to produce calcium hydroxide

Precipitate

a solid that is produced as a result of a chemical reaction in solution and separates from the solution

sulfurous acid (H₂SO₃)

air polluted with sulfurous acid reacts with o₂ to form sulfuric acid-- acid rain component-- diluted by water - not a problem in florida bc since we are in a peninsula its driven out by winds

Decomposition of metal hydroxides

all metals hydroxides EXCEPT THOSE IN GROUP 1 metals decompose when heated→metal oxide + Water - opposite of synthesis reaction Ex: Ca(OH)₂→CaO₊H₂O (AB)

activity series of elements example//more info.

aluminum can replace zinc 2Al (s) +3ZnCl₂→3Zn (s) + 2AlCl₃ Cobalt CAN NOT replace sodium Co (s) + 2NaCl→No rxn - shows how some metals react vigourously with water and acids-- replacing H and forming new compound - other metals (Zn and Fe) react with H in acids but reat with water only when its hot (Steam)

combustion reaction

burning of anything - substance combines with oxygen, releasing, large amount of energy in the form of heat and light-- fire Ex: burning of natural gas; propane, gasoline, and wood(hydrocarbon/carbohydrate)→Carbon dioxide and water - combustion of hydrogen →water vapor 2H₂ + O₂ →2H₂O - propane combustion C₃H₈ (g) + O₅ (g)→CO₂ (g) + 4H₂O(g)

symbol for reactant heated

can also have word heat or temp. instead of triangle word equation starts "when heated"

Chemical Equations

describe chemical reactions-- doesn't tell you the speed of reaction or if it actually occurs, how the bonding b/t atoms or ions change during reaction - represents with symbols and formulas the identities and relative molecular or molar amounts of the reactants and products in a chemical reaction (exothermic/endothermic)

word equation

equation in which the reactants and the products in a chemical reaction are represented by words - only has qualitative (descriptive) data Ex: Hydrogen gas reacts with oxygen gas to produce water PRACTICE-- writing it and and turning it to balanced formula equation (notebook)

Ag Pt Au

fairly nonreactive form oxides only indirectly

charge for group 9, group 10

group 9; +1-- have to loose one to get to 8 group 10; +2-- have to loose two to get to 8

Synthesis reaction-- water

hydrogen gas + Oxygen gas = dihydrogen monoxide (water) 2H₂+O₂→2H₂O

+ → ⇌ (s) or ↓ (l) (aq) (g) or ↑

in chemical equation +: in reactants-- "reacts with" →: to yield/produce ⇌: used in place of single arrow to indicate a reversible reaction (most reactions are reversible but this arrow means that they are more easily reversible) Reversible reaction: chemical reaction in which products reform original reactants (s) or ↓: reactant/product in solid state/can also be precipitate (l): reactant/product is in liquid state (water assumed as liquid unless told otherwise) (aq): reactant/product in an aqueous solution (dissolved in water)--when said it's been through water-purification process/added to water (g) or ↑: reactant/product in gaseous state (HOF BrNCl assumed as gas unless told otherwise)

formation of a gas

insoluble gas-- bubbles out of mixture ex: iron (II) sulfide + hydrochloric acid→hydrogen sulfide gas + iron (II) chloride FS +HCl → H₂S + FeCl₂ (aq)

Salt

ionic compound composed of a cation and the anion from an acid Ex: NaCl-- acid HCl

Decomposition of acids (always AB)

some oxyacids decompose into →nonmetal oxides ₊water - opposite of synthesis reaction Ex: carbonic acid decomposes to produce water and carbon dioxide H₂CO₃→H₂O + CO₂ - subtract out the water from the reactant and whatever is left is the nonmetal oxide

elements activity/reactivity

the ability of an element to react - the more readily an element reacts w/ other substance the greater its activity

Electrolysis

the decomposition of a substance by an electric current

What is the best container for an acid

the metal that is in the lowest place of the reactivity series because then it won react with the acid. Moreover, allowing it to be stored safely.

Chemical Reaction

the process by which one or more substances change to produce one or more different substances

How to follow law of conservation of mass

to balance numbers of atoms--add coefficients were necessary, NEVER change subscripts-- if you change them it changes the identity of the compound

Law of conservation of mass

total mass of reactants must equal the total mass of products for any given chemical reaction - atoms are neither created nor destroyed in ordinary chemical reactions

Synthesis reaction-- metal and halogens

undergo many synthesis reactions with many different metals Metal + halogen→ionic/covalent compound G1 and G2-- ioni compounds 2Na (s) + Cl₂ (s) →2NaCl - Fluorine so reactive combines with almost all metals

Enzymes/catalysts used in chemical reaction

used to speed up reactions-- DOES NOT change reaction happening - Pt (platinum) or MnO₂ (manganese dioxide) (enzyme examples) written on top of arrow word equation starts "in the presence of _____ catalyst"

formation of a precipitate

when cation of one reactant combines with anions of another reactant-- forms insoluble/slightly soluble compound-- precipiate forms bc VERY STRONG ATTRACTIVE forces b/t Pb+2 and I- anions-- other products in reaction don't take part in the formation of the precipitate Ex: aqueous potassium iodide reacts with aqueous lead (II) nitrate to produce potassium nitrate and lead (II) iodide 2KI (aq) + Pb(NO₃)₂ (aq)→2KNO₃ (aq) + PbI₂ (s)

Decomposition of metal carbonate

when metal carbonate heated it breaks down → metal oxide + carbon dioxide gas MCO₃⁻²→MO+ CO₂ (g) Ex: CaCO₃→CaO+ CO₂ (g) (AB)

Decomposition of metal chlorates

when metal chlorates heated→metal chloride + oxygen gas (O₂) when heated potassium chlorate decomposes to produce potassium chloride and oxygen gas 2KClO₃→2KCl + 3O₂ (g)

Avoid these mistakes when balancing equation

writing incorrect chemical formula for reactants or product trying to balance an equation by changing or adding subscripts-- can't be added deleted or changed

symbol for pressure at which reaction is carried our/exceeds normal atmospheric pressure symbol for temperature at which reaction is carried out

→ has # atm on top if exceeds normal atmospheric pressure write pressure on top word equation starts "under pressure" - for temp. at which carried out on top of arrow write temp. in degrees

displacement of metal in a compound by another metal

- metal that displaces the other metal has to be more reactive-- CATIONS BEING REPLACE Ex: Al more reactive than Pb Al (s) ⁺Pb(NO₃)₃ (aq)→Al(NO₃)₃ (s) + Pb (aq) solid aluminum reacts in aqueous lead (III) nitrate to produce aqueous aluminum nitrate and solid lead

displacement of hydrogen in an acid by a metal

- more active metal + acidic solution (ie- HCl) replacing hydrogen in the acid →produces metal compound (salt) +hydrogen gas - magnesium more reactive than hydrogen so can replace it - HYDROGEN replaced Mg (s) +HCl (aq)→H₂ (g) + MgCl₂

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

- reacts with steam (not cold water), and acids replacing hydrogen - react with oxygen to form oxides

Formation of a molecular compound **water

- some double displacement reactions~~very stable molecular compound (ie. water) one of compound Ex: HCl (aq) +NaOH (aq)→NaCl (aq) + H₂O (l) AB

Indications of a chemical reaction

1. change in energy (heat/light)-have to think of what causes it Ex: decomposition of ammonium dichromate 2. Production of a gas (bubbles) Ex:CO2 bubbles from when vinegar and baking soda mix 3. Formation of a precipitate(solid) 4. Change in color DON'T NEED ALL OF THEM FOR IT TO BE A CHEMICAL REACTION

important things to know about a chemical equation

1. coefficients indicate relative, not absolute amount of reactants and products-- show in smallest amount of atoms, molecules, or ions that satisfy law of conservation of mass in chemical reaction; can be seen as moles-- to obtain larger relative amounts must multiply e/a coefficient by e/a number Ex: H₂(g)+Cl₂(g)→2HCl 2. relative mass of the reactants and products of a chemical reaction can be determined from the reaction's coefficents-- multiply #of moles of element/compound present by molar mass Ex: 1mol H₂*2.2g H₂/1mol=2.02g H₂ 1 mol Cl₂ *70.9 g Cl₂/1mol- 70.9 g Cl₂ 2 mol HCl * 36.46 gHcl/1mol= 72.92g HCl - reactants mass added together= mass of products

How to balance equation

1. identify the names of the reactants and the products, and write a word equation-- write a formula equation by substituting names of the reactants and the products (DON'T FORGET ABOUT DIATOMIC MOLECULES) H₂O(l)→H₂(g)+O₂(g) 2. count number of atoms of specific elements on each side-- add coefficients NEVER CHANGE SUBSCRIPT bc that changes identity of compound 3. Balance with law of conservation of mass; read from left to right - balance different types of atoms one at a time - first balance the atoms of the elements that are combined and that appear only once on e/a side of the equation - balance polyatomic ions that appear on both sides of the equation as single units - balance H then O LAST 4. count to make sure it is balanced and when possible reduce coefficients; divide by greatest common factor-- can only reduce if all coefficients on the compounds can be reduced (if there isn't a coefficient in a compound it is assumed one therefore it is not reducible)

Steps to writing chemical equation

1. write a word equation--identify facts represented Ex: methane reacts with oxygen to produce carbon dioxide and water 2. replace the names of reactants and products with appropriate symbols and formulas-- formula equation-- MAKE SURE TO PUT STATE OF MATTER/if heated or pressured Ex: CH₄ (g) + O₂ (g) (bc diatomic)→CO₂(g)+H₂O(g) **NOT BALANCED 3.Balanced equation Ex: CH₄(g) +2O₂ (g)→CO₂ (g) + 2H₂O (g)

Synthesis reaction

AKA compound reaction starts with two or more reactants (elements or compounds) and ends up with one product (compound) A + X = AX - oxides/sulfides, mult. oxides dep on condition, water, metal and halogen, active metal oxides+water, nonmetal oxides+water, metal oxides and non metal oxides

double displacement reaction

AKA double replacement reaction the ions of two compounds exchange places in an aqueous solution to form two new compounds - STARTS WITH 2 ENDS WITH 2 (combustion sometimes does to but products are H2O and CO2-- look out!) AX + BY→AY + BX 1st compound formed→precipitate, insoluble gas (bubbles out of solution), or molecular compound *usually water 2nd compound formed→soluble remains dissolived in solution

Single-dispplacement reactions

AKA replacement reaction one element replaces a similar element in a compound - many happen in an aqueous solution and usually don't need energy Element + compound→element and compound - check if reaction happens through reactivity series - displacement on -- metal in comp, H in water, hydrogen in an acid, halogen

Synthesis reaction-- Iron and nonmetals oxides

iron (all aunt valerie's-- iron does it most often) and nonmetals react with O₂ to form oxides (ide-anion)-- can form multiple compund types depending on condition of reactants (metal/nonmetal) Ex: 2Fe(s) + O₂ (g) →2FeO-- that means that iron had a +2 charge-- Iron reacts with oxygen gas to produce Iron (II) oxide 4Fe + O₂ (g)→2Fe₂O₃-- that means that iron had a +3 charge-- Iron reacts with oxygen to produce Iron (III) oxide

Displacement of H in water by least active metals

least active metals (ie- Fe) + with steam (water) → metal oxide + hydrogen gas - HYDROGEN replaced Fe (s) + H₂O (g)→Fe₃O₄ (s) + 4H₂ (g)

calcium oxide

lime or quick lime; used to make concrete

Hydrocarbon

molecular compounds soley composed of hydrogen and carbon - when you see a word/chemical formula with just hydrogen and carbon it is a hydrocarbon write it as that

Displacement of H in water by most active metals

most active metals (g1,2) + water →metal hydroxide + hydrogen gas - CATIONS displaced Ex: Na (s) +H₂O (l)→NaOH (aq) +H₂ (g)

Decomposition reaction

opposite of synthesis - a single compound undergoes a reaction that produces two or more simpler substances (compounds or elements) - take place only when energy in the form of electricity or heat is added - decomp.-- of binary compounds, metal carbonates, metal hydroxides, metal chlorates, acids,

Synthesis reaction-- with oxides of nonmetals (always AB)

oxides of nonmetals react with water to produce oxyacids (always AB) Ex: SO₂+ H₂O→H₂SO₃ (AB) Sulfur dioxide (ITS A COMPOUND NOT POLYATOMIC ION BC NO CHARGE AND IT'S BY ITSELF) reacts with water to produce sulfurous acid - add oxygen together for the oxyacid and the H stays the same

Characteristic/requirements of chemical equations

properly written-- summarizes any chemical change 1. must state known facts-- all reactants and products must be identified 2. correct formulas must be used for reactants and products-- knowledge of formulas (diatomic elements receive subscript of 2-- regular ones receive no subscript) - exceptions are S₈ and P₄-- reflecting unique arrangement 3. follow law of conservation of mass~~ same number of atoms of e/a element must appear on e/a side of equation

Li, Rb, K, Ba, Sr, Ca, Na

react with cold H₂O and acids replacing hydrogen react with oxygen forming oxides

H₂, Sb, Bi, Cu, Hg

react with oxygen forming oxides

formula equation

represents the reactants and products of a chemical reaction by their symbol or formulas - provides qualitative (no info on amount of reactants/products) statement - doesn't take law of conservation of mass into account-- have to BALANCE EQUATION

Decomposition of binary compounds

simplest kind-- heat/energy added - binary compounds decompose into elements Ex: 2Al₂O₃→4Al+ 3O₂(g) - how oxygen was discovered-- heated mercury (II) oxide to produce mercury and oxygen-- Joseph Priestly

Coefficient

small whole number that appears IN FRONT of a formula in a chemical equation -- used to balance equations - specifies relative number of moles of the substance has - if non written it is assumed to be one - applies to e/a element in compound-- multiplies number of atoms of e/a element indicated in chemical formula Ex: 2H₂O-- 4 hydrogen and 2 oxygen

Synthesis reaction-- with metal oxides and nonmetal oxides

some metals and nonmetal oxides react with e/a other to form salts Ex: CaO + SO₂ →CaSO₃ Calcium oxide (metal oxide ion) reacts with sulfur dioxide (nonmetal oxide compound) to produce calcium sulfite