acid base salts

Question 1

definition of acid

Answer 1

acid is a proton donor(H+),produces hydrogen ions when dissolved in water

Question 2

why does HCl work in water but not methylbenzene

Answer 2

acid behaviour only takes place when hydrogen chloride dissolved in water,HCl is a covaalent substance,when dissolved in methylbenzene substance still contains hydrogen chloride molecules,in water hydrogen chloride molecules dissociate into hydrogen ions and chloride ions

Question 3

what are the uses of acid

Answer 3

HCl:digest food in stomach,sulfuric acid:electrolyte in car batteries,carbonic acid:fizzy drinks,nitric acid:makes fertilizers and explosives,ethanoic acid:make vinegar and preservatives,Tartaric acid:used in fruit juice

Question 4

organic acid definition and examples

Answer 4

Naturally occuring,weaker,less corrosive,citric acid(lemon),lactic acid(sour milk),malic acid(apple)

Question 5

Mineral acid definition and examples

Answer 5

man made,stronger,more corrosive,sulfuric acid,nitric acid,hydrochloric acid,carbonic acid,sulfurous acid,phosphoric acid.

Question 6

Physical properties of acid

Answer 6

sour taste,turns blue litmus red,universal indicator red,methyl orange-red,thymophthalein-colourtless,phenophtalein-colourless,they are electrolytes which conduct electricity because ions are produced in solution

Question 7

Chemical properties

Answer 7

acid+metal=salt+hydrogen,acid+carbonate=salt+water,carbon dioxide,acid+base=salt+water(neutralisation,acid+metal oxide=salt +water,acid+metal hydroxide=salt+water.

Question 8

Properties of strong acids

Answer 8

fully ionise in solution to produce ions,concentration of hydrogen ions are higher so more bubbles observed,good proton donor,strong electrolyte(good conductor of electricity)

Question 9

properties of weak acids

Answer 9

partially ionised in solution,double arrow in equation,concentration of hydrogen ions lower,poor proton donor,weak electrolyte(bad conductor of electricity)

Question 10

Strength and concentration of acid

Answer 10

strength(fully or partially ionise),concentration(amount of particles dissolved in a unit volume).

Question 11

what is the basicity of acids

Answer 11

number of hydrogen atoms in an acid which can be replaceable by metal ion

Question 12

Examples of monobasic,dibasic and tribasic acids

Answer 12

Monobasic:HCl,HNO3,Dibasic:H2SO4,H2CO3,Tribasic:H3PO4,reaction faster in dibasic than monobasic and etc.

Question 13

Definition of base

Answer 13

proton acceptor

Question 14

What is usually a base

Answer 14

metal oxide or metal hydroxide

Question 15

What is an alkali

Answer 15

A soluble base that produces OH- in aqueous solution,it is a metal hydroxide

Question 16

Example of common alkalis

Answer 16

sodium hydroxide solution,potassium hydroxide solution,calcium hydroxide solution(limewater)

Question 17

4 Use of bases

Answer 17

sodium hydroxide:make soap,Potassium hydroxide:dye cloth,Calcium hydroxide:adjust acidic concentration of soil,Ammonia solution:Make fertiliser

Question 18

Physical properties of alkali

Answer 18

Bitter taste,soapy feeling,turns red litmus paper blue

Question 19

INdicators change in alkali Litmus,universal,methyl orange,thymolphtalein,phenophtalein

Answer 19

Litmus:blue,universal:blue,methyl orange:yellow,thymolphtalein:blue,phenophtalein:pink,all common alkalis are electrolytes

Question 20

Chemical equations of bases

Answer 20

alkali+ammonium salt=salt+water+ammonia(with heating),alkali+acid=salt+water,Alkali+metal salts=metal hydroxides+salt (most metal hydroxides are insoluble in water so alkalis give precipitates with solutions of most metal salts

Question 21

strong and weak alkalis

Answer 21

strong alkalis fully ionise in solution to produce ions,all alkaline molecules become ions in water,weak alkalis are partially ionised in solution,only few molecules react with water to form ions

Question 22

Types of oxides

Answer 22

Acidic,basic,amphoteric,neutral

Question 23

Definition of acidic oxides and examples

Answer 23

react with water to produce acids,usually oxides of non metals,sulfur trioxide,sulfur dioxide

Question 24

Definition of basic oxides and examples

Answer 24

react with water to produce alkalis,usually oxides of metals.Potassium oxide,sodium oxide

Question 25

Definition of amphoteric oxide and examples

Answer 25

behave as an acidic/basic oxide,react with acids/alkalis to produce salts,usually oxides of metals.Aluminum oxide,zinc oxide,lead(II)oxide

Question 26

Definition of Neutral oxide and examples

Answer 26

insoluble in water,no reaction with acid/alkali,oxides of non metals.Carbon monoxide,nitrogen monoxide

Question 27

pH definition

Answer 27

measure of strength of an acid or alkali

Question 28

what is a pH scale

Answer 28

set of values ranging from 0 to 14.less than 7=acidic,7 is neutral,more than 7 is alkali

Question 29

what happens as ph increases and decreases

Answer 29

conc of OH- ions increase as ph increase and conc of H+ions increase as ph decreases

Question 30

indicators change colour in solution of differnt pH values.Methyl orange,litmus,phenophtalein

Answer 30

Methyl orange acidic:red pH4 colour change,Alkaline:yellow.Litmus Acidic:red pH 7 colour change,Alkaline:blue.Phenopthalein Acidic:colourless pH 9 colour change,Alkaline:pink

Question 31

2 methods to determine pH of solution

Answer 31

Universal indicator and pH meter-electric meter more accurate than indicator.

Question 32

Colour in universal indicator at different pH

Answer 32

1,2=red,3,4=orange,5,6 yellow,7=green,8,9,10=blue-green,11,12=blue,13,14=violet

Question 33

why is soil pH controlled

Answer 33

if pH of soil is too low or high plants do not grow well,most plants require soil pH of 7-8 to grow.slaked lime or quick lime is added to increase pH of soil above pH7 which is called liming the soil

Question 34

definition of a salt

Answer 34

substance formed when hydrogen of an acid is partially or completely replaced by a metal ion or an ammonium ion

Question 35

Acids and their salts

Answer 35

acids with name ending with'ic' will form salt ending in 'ate'.acid with name ending with'ous' will form salt with name ending in ite.

Question 36

Difference of normal salt and acid salts

Answer 36

normal salt is one which all hydrogen ions are replaced.Acidic salts is one in which only some of hydrogen ions of dibasic or tribasic acid are replaced

Question 37

what are hydrated salt

Answer 37

salts which contain water molecules inside their crystal structure essential for shape and colour,called water of crystallisation.number of water molecules present in salt is called degree of hydration.When heated salts lose water of crystallisation(lose shape and colour),salts without water of crystallisation called anhydrous salts

Question 38

use of salts

Answer 38

medical,manufacture fertiliser,paint,photography

Question 39

what to do with salt with high gradient in solubility curve and almost no change in solubility curve.

Answer 39

evaporate to dryness or cooling

Question 40

preparation of salts for insoluble and soluble salt

Answer 40

insoluble salt=reactant used and other products formed must be soluble to obtain salt by filtration.soluble salt=reactant used and other products formed must be insoluble so salt can be obtained by filtration as filtrate