Acids, Bases and Salts Flashcards
Indicators
Substances which indicate whether compound is acidic or basic by change in colour
Natural Indicators
red cabbage extract, turmeric, hydrangea, litmus
Artificial Indicators
Mehtyl Orange, Phenopthalein
TURMERIC
yellow in color, remains yellow in acidic soln, turns red in basic soln
HYDRANGEA
blue in color, remains blue in acidic soln, turn pink in basic soln
METHYL ORANGE
red color in acidic soln, yellow color in basic soln
PHENOPTHALIEN
colorless, remains colorless in acidic soln, turns pink in basic soln
RED CABBAGE EXTRACT
red in color, remains red in acidic soln, turns green in basic soln
LITMUS
base- turns red litmus blue
acid- turns blue litmus red
OLFACTORY INDICATORS
indicate whether substance is acidic or basic in nature by changing odor or smell
VANILLA EXTRACT
characteristic smell remains as it is in acidic soln but cannot be detected in basic soln
Onion
characteristic smell remains as it is in acidic soln but cannot be detected in basic soln
EXAMPLES of OLFACTORY INDICATORS
vanilla extract, onion
ACIDS
sour in taste, conduct electricity
ORGANIC ACIDS
naturally occuring, weak in nature
EXAMPLES OF ORGANIC ACIDS (6)
Lactic Acid, Tartaric Acid, Oxalic Acid, Methanoic/formic, Acetic Acid, Citric Acid
LACTIC ACID
SOUR MILK/CURD
TARTARIC ACID
TAMARIND, UNRIPE GRAPES
OXALIC ACID
TOMATOES
methanoic acid is also known as
formic acid
Methanoic Acid
Ant’s sting, nettle leave sting
Citric Acid
citrus fruits like lemon, lime
Acetic Acid
Vinegar
MINERAL ACIDS
prepared from minerals of earth, man made, generally strong in nature
which mineral acid is not strong in nature
Carbonic acid (H2CO3)
three most used mineral acids
Sulphuric, Hydrochloric and Nitric
Acetic acid (in form of vinegar) is used in?
pickles, ketchup
Tartaric Acid is used in making
baking powder
carbonic acid is used in making
fizzy drinks
why should water be added gradually while diluting acid?
diluting acid is highly exothermic process–> lot of heat is produced
if water is added at once, large amount of heat would be evolved which would convert some of the water to steam, this might lead to acid splashing and causing burns
when acids react with metal
hydrogen gas is formed along with salt
example of metal reacting with acid
zinc + sulphuric acid —> zinc sulphate + hydrogen
Zn+H2SO4 —> ZnSO4+H2
why should food not be stored in metal containers?
because acid in food will react with metal to form harmful metal compounds
acid react with metal carbonate/hydrogen carbonate
to form salt, CO2, H2O
example of metal carbonate reacting with acid
sodium carbonate + hydrochloric acid—> sodium chloride + carbon dioxide+ water
Na2CO3 + 2HCl —> 2NaCl+ CO2+ H2O
metal carbonate/hydrogen carbonate + HCl (hydrochloric)
metal chloride+ CO2 + H2O
metal carbonate/hydrogen carbonate +H2SO4 (sulphuric)
metal sulphate + CO2 + H2O
example of metal hydrogen carbonate reacting with acid
sodium hydrogen carbonate + hydrochloric acid –> sodium chloride+ carbon dioxide + water
NaHCO3+HCl—> NaCl+CO2+H2O
lime water and carbon dioxide
Ca(OH)2 + CO2 —> CaCO3 + H2O
calcium hydroxide + carbon dioxide + calcium carbonate + water
lime water is
calcium hydroxide, Ca(OH)2
quicklime is
CaO, calcium oxide
slaked lime
Ca(OH)2
what can be observed when CO2 passes through lime water
lime water turns milky due to formation of white precipitate (CaCO3)
what can be observed when excess CO2 passes through
when excess CO2 is passed, white precipitate (CaCO3) dissolves due to formation of calcium hydrogen carbonate and solution becomes clear
CaCO3+CO2+H20—> Ca(HCO3)2
different forms of calcium carbonate (CaCO3)
egg shells, chalk, limestone, marble
Acid react with base
to form salt and water, neutralization reaction
example of acid reacting with base
NaOH (aq) +HCl (aq) —> NaCl (aq) +H2O (l)
]sodium hydroxide + hydrochloric acid –> sodium chloride + water
acid react with metal oxide/hydroxide
to form salt and water
example of acid reacting with metal oxide
CuO (s) + 2HCl (aq)—-> CuCl2 (aq) +H2O (l)
what can be observed when copper oxide reacts with hydrochloric acid
change in color from black to blue-green
this reaction shows basic nature of metal oxide
Acids and H+ ions
acids disassociate in water to produce H+ ions
are all compounds having hydrogen acidic?
no because some compounds (like glucose) contain hydrogen but do not disassociate in water to form H+ ions
why do aqueous acids conduct electricity
aqueous acids conduct electricity because of charged particles (ions) present in them
why does rain water conduct electricity but distilled water doesn’t?
rain water dissolves with CO2 which is an acidic gas while falling through atmosphere to form carbonic acid (H2CO3). Due to presence of acid, electricity is conducted by rain water. Rain water also dissolves with other acidic gases like SO2, NO2 etc to form acid
do acids show acidic behavior in absence of water?
no, because in absence of water acids cannot disassociate into H+ ions
Strong acids
completely ionize in water to produce large amount of H+ ions
they react rapidly and are strong electrolytes due to large amount of ions
what happens to H+ ions in water
H+ ions attach to polar water molecules to form hydronium ions
H+ ions + H2O—> H3O+ ions
Weak Acids
partially ionize in water and produce small amount of H+ ions, react slowly and low electrical conductivity
Example of strong acid
H2SO4 (sulphuric), HNO3 (Nitric)
Example of weak acid
CH3COOH
⇌ what does this double arrow indicate in a chem eqn
indicates partial ionization
USES of sulphuric acid (9)
manufacture of fertilizers ( ammonia sulphate ), paints, dyes, chemicals, plastics, synthetic fibres, detergents, explosives, car batteries
uses of nitric acid (4)
fertilizers (like ammonium nitrate), explosives ( TriNitro Toluene), dyes and plastic
Uses of hydrochloric acid (5)
removing oxide film from steel objects
removing ‘scale’ from inside boilers, used in textile, food and leather industry
ALKALI
water soluble bases
examples of alkali
KOH, NH4OH, NaOH, Ca(OH)2, Mg(OH)2
why are alkali more useful than bases
most chemical reactions take place in water, this is why alkali are more useful
Bases and OH- ions
bases disassociate in water to form OH- ions
Strong Bases
completely ionise in water and produce large amount og OH- ions
Weak Bases
partially ionize in water and produce small amount of OH- ions
Examples of strong bases
NaOH, KOH
Examples of weak bases
NH4OH, Ca(OH)2, Mg(OH)2
bases react with metal
for H2 gas
base + metal —> salt + H2
example of metal reacting with base
sodium hydroxide + zinc —> sodium zincate + hydrogen
2NaOH (aq) + Zn(s) –> Na2ZnO2(aq) +H2 (g)
base react with acid
to form salt and water
example of base reacting with acid
2NaOH+ H2SO4 —> Na2SO4 + 2H2O
sodium hydroxide + sulphuric acid —> sodium sulphate + water
Neutralization reaction in terms of ions
H+ (aq) + OH- (aq) —-> H20 (l)
H+ ion from acid and OH- ion from base
Base react with non metal oxide
to form salt and water
example of base + non metal oxide
Ca(OH)2+ CO2 —-> CaCO3 +H2O
non metal oxides are ________ in nature
acidic
use of sodium hydroxide
soap, paper, rayon (synthetic fibre)
use of slaked lime
bleaching powder
use of magnesium hydroxide
antacid
use of sodium carbonate
washing soda, softening hard water
use of sodium hydrogen carbonate
baking soda, making baking powder, antacid, soda-acid fire extinguisher
when and who devised pH scale
1909, Sorenson
what is pH scale
it is a scale that represents strength of acid and bases through concentration of H+ ions present
pH scale is inversely proportionate to concentration of H+ ions
what is pH level of neutral substances
pH level of neutral substances is exactly 7
pH level of acid?
acidic soln have pH less than 7
strong acid have pH 0 to 3
weak acid have pH 4 to 6
pH level of bases?
more than 7
weak base have pH 8 to 10
strong base have pH 11 to 14
Universal Indicator
mixture of many different indicators give different colors at different pH value, They indicate strength of acidic/basic solution
what are different colors at different concentration of H+ ion in universal indicator
strong acid---> red tones weak acid ---> orange tones neutral --> green weak base --> blue tones strong base ---> violet tones
ACIDITY and its remedy
when excess of HCl is produced, it leads to indigestion
REMEDY - antacid, an antacid can neutralize excess acid and give relief
Antacid and their examples
mild bases that dont have any toxic effect on body
examples- Mg(OH)2 - milk of magnesia/ magnesium hydroxide
NaHCO3 - sodium hydrogencarbonate
Tooth Decay
bacteria in mouth break down sugar to form acid, when pH of acid falls below 5.6 it becomes strong enough to corrode enamel of teeth
how to prevent tooth decay
toothpastes are basic in nature (generally have pH of 8) and they neutralize excess acid, we should clean our teeth with toothpaste regularly
eat less sugary food
Plant growth and soil pH
plant grow best when pH of soil is around 7
how can we treat soil that is too acidic
CaO (quicklime), Ca(OH)2 (lime water), CaCO3 (chalk) can be used to treat acidic soil as they are basic in nature and can neutralize excess acid
how can we treat soil that is too basic
decaying organic matter (manure/compost)
how does pH level affect aquatic animals
when rain water has pH of 5.6, it is considered acidic . Too much acid rain can lower pH level of lakes/rivers. Aquatic animals can only survive within narrow range of pH change, this is why, when lakes become too acidic, aquatic animals die
how to prevent death of aquatic animals (caused by high acidity of lake)?
CaCO3 (calcium carbonate) can be added to lakes to raise their pH levels and neutralize excess acid
why cant Venus support life
its atmosphere has thick white and yellow clouds of sulphuric acid, body can only work well in pH range around 7, this is why venus is inhabitable
what is there in a bee’s sting? remedy for sting?
bees inject acidic liquid to protect themselves
remedy- mild base like baking soda
what is there in a wasp’s sting? remedy for sting?
wasp inject alkaline liquid, remedy - mild acid like vinegar
what is there in a ant’s sting? remedy for sting?
ants inject methanoic acid, remedy - mild base like baking soda
what is there in a nettle leave’s sting? remedy for sting?
nettle leaves have stinging hair that inject methanoic acid into skin of animal that touches them
TRADITIONAL REMEDY - using leaves of dock plant (which grow near nettle plant). dock plant leaves have basic chemicals that neutralize the acid
other remedy - mild base like baking soda