C7 - Acids, bases & salts (ionic equations, preparing salts) Flashcards
type of bonding in acids & bases & salts
acid - covalent - shared pair of e btw non-metals; attraction of protons & e
base - ionic - transfer of e btw metal & non- metal; electrostatic force of attraction btw (+) & (-) ions
salts - ionic
acidic or basic:
-metal oxides
-non- metal oxides
-basic
-acidic
what colour does litmus paper turn under acid & alkaline (need to be soluble)
-acid - red
base - blue
3 kinds of indicators
-universal indicator
-methyl orange solution
-phenolphthalein
base colour for
-universal indicator
-methyl orange solution
-phenolphthalein
-universal indicator - blue
-methyl orange solution - yellow
-phenolphthalein - dark pink
acid colour for
-universal indicator
-methyl orange solution
-phenolphthalein
-universal indicator - red
-methyl orange solution - red
-phenolphthalein - colourless
3 common acids/ strong acids
-hydrochloric acid HCL
-sulfuric acid H2SO4
-nitric acid HNO3
3 common bases/ weak acids
-Sodium hydroxide NaOH
-Potassium hydroxide KOH
-Calcium hydroxide Ca (OH)2
-eg. Magnesium hydroxide
2 weak acid & base
acid:
-ethanoic acid
-citric acid
base:
-ammonia hydroxide
what is pH
-measure of acidity
-1 pH change = 10^1 times [H+ ions]
define strength
-how much compound dissociated in a liquid
difference btw strong & weak acids/bases
-strong: dissociated fully in water eg. HCl -> H+, Cl-
-weak: dissociated partially in water
define concentration
amount of compounds in a given volume
formula for concentration
-mass/ volume
- g / (d/c)m3 = g(d/c)m3
difference btw concentration & strength
-more con. more H+ ions, more products
-stronger, faster rate of reaction
define alkaline
water soluble base
define acid & base
acid - proton donners; source of H+ ions
base - proton acceptors; source of OH- ions
why are H+ ions called protons
-e is given away
-only neutron & proton in nucleus
-proton had + charge
relationship btw pH & ions
-higher the concentration of H+ ions, lower the pH
-higher the concentration of OH- ions, higher the pH
pH of acid, neutral, alkaline
acid - <7
neutral - 7
base - >7
pH of metal oxides, hydroxides & carbonates
basic
pH of non- metal oxides, hydroxides & carbonates
acidic
define solute, solvent, solution
solute - substance which dissolved in solvent
solvent - substance which solute dissolves in
solution - mixture of solute & solvent
define metalloids
-non- metals with metallic properties
eg. boron, silicon
define amphoteric & eg.
-substance can react as basic & acidic
-Zinc & Aluminum oxides
define neutral oxides & eg.
-substances that don’t react with acids or bases
-eg. carbon monoxide CO, dinitrogen oxide N2O
define corrosive
break down of substance
note: reactions with acids & bases usually happens in water - so aqueous
requirement for metals to react with acid
-metal must be more reactive than hydrogen to react with acid & displace Hydrogen
neutralization reaction
acid + base -> neutral salt + water
is neutralization a redox reaction, why
no, oxidations states aren’t changed
where is neutralization used in & what bases used
neutralize acidic soil to grow plants
eg. CaO, Ca(OH)2, CaCO3
define thermal decomposition reaction
when heating 1 reactant gives many products
ammonia & ammonium ion symbol
ammonia - NH3 - alkaline
ammonium ion - NH4+
what type of salts are ammonium salts
weak adics
how is ammonia gas created using ammonium chloride
-thermal decomposition
-heat ammonium chloride NH4Cl
define spectator ion
ion which charge remains same in reaction
how to do ionic equations
-must in aqueous
-solid, liquid & gas are 0 chagre unless aqueous
-single elements are 0 charge
-water is 0 charge
-balance equation
-cancel spectator ions
-balance charges
note: oxidation state & charge is same except for polyatomic ions
3 ways to make salt
-titration - soluble acid & base
-excess solid method - insoluble base/ metal + acid ( 1 of reactant is insoluble)
-precipitation method - insoluble salt
how to decide which method to make salt
-is salt soluble?
-yes
-are reactants soluble?
-yes; titration
-no; excess solid method
-no; precipitation
titration process
-add acid to burette
-add acid to alkaline until indicator changes colour & calculate volume of acid added
-transfer solution to evaporating basin & heat to evaporate water
-uses burette & pipette
excess solid method
-Heat acid & react it with excess metal/ base/ carbonate
-filter mixture to remove excess solid
-heat filtrate to evaporate until crystals form
eg. H2SO4 & CuO
why is substance put in excess for excess solid method
so all acid particles react
what to add if want to decolourise solution
-add decolourising charcoal
precipitation method
-2 soluble solutions are mixed
-filter the precipitate
-wash salt with distilled water
-filter again to deionize salt
-heat it
eg, NaCl + AgNo3 - white precipitate, KI + AgNO3 - yellow ppt
what is 1 mole equal to
-1 mole = 6.02 x 10^23
-no. molecules in a mole
are they soluble:
1 -all G1 compounds, sodium, potassium, ammonium salts
2 -all nitrates
3 -all chlorides
4 -all sulfates
5 - all hydroxides & carbonates
1 - soluble
2 - soluble
3- all soluble except silver & lead chloride
4 - all soluble except calcium, barium & lead
5 - all insoluble except sodium, potassium & ammonium
insoluble compounds:
-silver & lead chloride
-calcium, barium & lead sulfates
-all hydroxides & carbonates except sodium, potassium & ammonium
reactions with acids
-metal (solid) + acid -> salt + hydrogen
-metal oxide + acid -> salt + water
-metal hydroxide + acid -> salt + water
-meta carbonate + acid -> salt + water + carbon dioxide
-base + acid -> neutral salt + water
reaction with bases
-acid + base
-base + ammonium salt - salt + ammonia (g) + water
gas tests:
-hydrogen
-oxygen
-carbon dioxide
-ammonia (alkaline)
-chlorine
-hydrogen - lit splint combusts with squeaky pop
-oxygen - glowing splint will relight
-carbon dioxide - limewater turn cloudy
-ammonia - damp red litmus paper turns blue, has pungent smell
-chlorine - damp blue litmus paper turns red before bleaching it white
define cations & anions
cations - positively charged metal ions
anions - negatively charged non - metal ions
test for cations: flame test (colour of flame)
-lithium
-sodium
-calcium
-potassium
-copper
-lithium - red
-sodium - yellow
-calcium - orange
-potassium - lilac
-copper - green
test for aqueous cations: reacting with NaOH (aq) in detail (all gives ppt except NH4)
-ammonium ion ( + )
-aluminum ion ( 3+ )
-zinc ion (2+ )
-calcium ion (2+ )
-copper ion (2+ )
-chromium ion ( 3+ )
-iron (II) ion (2+ )
-iron (III) ion (3+ )
-ammonium ion - ammonium salt + base = damp red litmus paper turns blue
-aluminum ion - white ppt, soluble in excess giving colourless solution
-zinc ion - white ppt, soluble in excess giving colourless solution
-calcium ion - white ppt, insoluble in excess
-copper ion - light blue ppt, insoluble in excess
-chromium ion - green ppt, soluble in excess
-iron (II) ion - green ppt, insoluble in excess
-iron (III) ion - red - brown ppt, insoluble in excess
note: precipitate short form - ppt
define ppt
solid insoluble product
test for aqueous cations: reacting with NH3 (aq)
-ammonium ion ( + )
-aluminum ion ( 3+ )
-zinc ion (2+ )
-calcium ion (2+ )
-copper ion (2+ )
-chromium ion ( 3+ )
-iron (II) ion (2+ )
-iron (III) ion (3+ )
-ammonium ion - nothing
-aluminum ion - white ppt, insoluble in excess
-zinc ion - white ppt, soluble in excess giving colourless solution
-calcium ion - no ppt or slightly white
-copper ion - light blue ppt, soluble in excess a giving dark blue solution
-chromium ion - grey - green ppt, insoluble in excess
-iron (II) ion - green ppt, insoluble in excess
-iron (III) ion - red - brown ppt, insoluble in excess
test for anions:
-carbonate CO3 ( 2- )
-chloride Cl ( - )
-bromide Br ( - )
-iodide I ( - )
-nitrate NO3 ( - )
-sulfate SO4 ( 2- )
-sulfite SO3 ( 2- )
-carbonate - add dilute HCl - CO2 produced makes limewater cloudy
-chloride - add HNO3 & AgNO3 (aq), forms white ppt
-bromide Br - add HNO3 & AgNO3 (aq), forms cream ppt
-iodide - add HNO3 & AgNO3 (aq), forms yellow ppt
-nitrate - add NaOH (aq) & Al, NH3 produced makes damp red litmus paper blue
-sulfate - add HNO3 & Ba(NO3)2 (aq), forms white ppt
-sulfite - add dilute HCl, warm & gently, SO2 produced turns acidified potassium manganate purple to colourless
note: rinse ppt. in distilled water to make sample pure
what are hydrated salts
-salts containing water
-written as: salt formula. (no.) H2O
note: not all metals react with acids
give eg.
-Au, Ag, Cu, Pt
note:
-acids can’t react with acids, bases can’t react with bases
-neutral compound/ noble gases don’t react
-reactions with acids & bases usually happens in water - so aqueous, unless with metal (solid) + acid or ppt is formed
-no colour = colourless
-sugar is neutral
-CO2 is an acidic oxide
-CO3 is a weak base
-H2 is flammable
-carbonic acid H2CO3
-all lead salts are insoluble
-iodide compounds are usually yellow
-any metal compounds except transition metal compounds are white (including ppt.)
-oxides are formed with steam, OH are formed with water
-Chlorine is acidic
-when I2 element is heat, sublimation happens, turns into a purple vapor
-copper compounds are blue usually
-to get hydrated salt, wash then heat
define standard solution
-solution containing an accurately known concentrations of an element/ compound
uses of lighted splint to find H2, O2, CO2
H2 - sqeuaky pop
O2 - splint will relight
CO2 - light in splint will die
how to find concentration, mass / volume of compound added
-formula
-write which part you have
-find the remaining part for reactant 1
-write balanced formula for reaction
-find ratio of reactants
-multiply as needed
-find the missing part of the equation for reactant 2
-[ compound formula ] = concentration of ____
note: gold, silver, copper, platinum doesn’t react with dilute acids because they’re lower than H2 in reactivity series
note: to know which reactant to put in excess, check states of products & if you can separate them later
note: to find evidence that solution contains a compound, find tests for the specific elements in the compound
note: CaO (lime), Ca(OH)2 (slaked lime), CaCO3 (limestone) can be used to neutralise acidic soil
