chp water

Question 1

define solubility

Answer 1

the solubility of a solute in a solvent at a particular temperature is the maximum amount of solute in grams that will saturate 100g of the solvent at that temperature

Question 2

formula of solubilty

Answer 2

weight of solute/weight of solvent * 100 at t degree

Question 3

why is water called a universal solvent

Answer 3

water has the ability to dissolve a large number of substances as well as gases and hence it can dissolve almost every common substance and is therefore called a universal solvent

Question 4

what do u mean by solute

Answer 4

the substance which dissolves in a solvent so as to form a solution is called a solute

Question 5

def solvent

Answer 5

the liquid or medium of dissolution which allows the solute to dissolve so as to form a solution

Question 6

def solution

Answer 6

the homogenous mixture of solute in the solvent is called solution

Question 7

def dilute solution

Answer 7

when the solute is relatively smaller than the solvent on a given mass it is called a dilute solution

Question 8

def concentrated solution

Answer 8

when the solute is relatively larger compared to the solvent in a given mass it is said to be a concentrated solution

Question 9

state characteristics of true solutions

Answer 9

it is a homogenous mixture can pass through filter paper it does not settle down and cannot be seen through a microscope the solute can be removed by physical means but not by chemical means and therefore true solution is a mixture

Question 10

what is meant by unsaturated solution

Answer 10

a solution which can dissolve more of the solute at a given temperature is called unsaturated solution

Question 11

def unsaturated solution

Answer 11

a solution which cannot dissolve more of the solvent at a given temperature is called unsaturated solution

Question 12

how can a saturated solution become an unsaturated solution

Answer 12

1) by boiling
2) by adding more solvent

Question 13

def super saturated solution

Answer 13

it is when the solution can hold more of a solute at a given temperature than that present in a saturated solution

Question 14

def crystallisation

Answer 14

the process of deposition of crystals from an hot saturated solution on cooling gently is called crystallisation

Question 15

def water of crysatllisation

Answer 15

the fixed number of water molecules which enters into a loose chemical combination with the substance when the substance is crstallised from its hot saturated solution is called water of crystallisation

Question 16

def hydrated crystals

Answer 16

it contains fixed number of water molecules in loose chemical combination with the substance eg cuso4.5h2o

Question 17

def anhydrous crystals

Answer 17

it does not contain any fixed number of molecules in loose chemical combination with the substance

Question 18

name a dihydrate crystal

Answer 18

gypsum caso4.2h2o

Question 19

lime salt petre

Answer 19

cano3twice.4h2o

Question 20

name a pentahydrate cystal

Answer 20

blue vitriol cuso4.5h2o

Question 21

epsom salt

Answer 21

mgso4.7h2o

Question 22

name a heptahydrate crystal

Answer 22

feso4.7h2o

Question 23

glaubers salt

Answer 23

na2so4.10h20

Question 24

washing soda

Answer 24

na2co3.10h2o

Question 25

what is efflorescent substance

Answer 25

they are substances which on exposure to atmosphere looses their moisture and change to amourphous state

Question 26

what is deliquescent substance

Answer 26

they are substances which on exposure to atmosphere absorb moisture and change to a saturated solution

Question 27

state three examples of efflorescent substance

Answer 27

washing soda copper sulphate glaubers salt

Question 28

state 5 examples of deliquescent substances

Answer 28

fused calcium chloride iron3 chloride sodium hydroxide pottasium hydroxide magnesium chloride

Question 29

why does common salt turn moist on exposure to air

Answer 29

common salt is not deliquescent it contains impurities of calcium and magnesium chloride which are deliquescent therefore they absorb moisture and hence table salt becomes moist on exposure to air

Question 30

when does efflorescence occur and deliquescence with respect to vapour pressure and atmospheric humidity

Answer 30

efflorescence occurs when the vapour pressure of the hydrated crystal exceeds the vapour pressure of atmospheric humidity and deliquescence occurs when the vapour pressure of the deliquescent crystal solution is very low compared to the vapour pressure of atmospheric humidity

Question 31

what is hygroscopic substance

Answer 31

they on exposure to atmosphere absorb moisture but do not change their state

Question 32

example of hygroscopic substance

Answer 32

quick lime anyhrous calcium chloride sulphuric acid

Question 33

what is hard water

Answer 33

water is said to be hard when it does not lather readily with ordinary soap and hence wastes soap

Question 34

def soft water

Answer 34

water is said to be soft when it lathers readily with ordinary soap and hence does not waste soap

Question 35

what causes water to be hard

Answer 35

calcium and magnesium bicarbonates sulphates and chlorides

Question 36

state the two types of hard water define them and state how they are caused and how to turn them soft

Answer 36

the two types of hard water are temporary hard water and permanent hard water temporary hard water can be removed by boiling but permanent hard water cannot be removed by boiling but can be removed by adding washing soda temporary hard water is caused due to calcium and magnesium bicarbonates and permanent hard water is caused due to calcium and magnesium sulphates and chlorides

Question 37

disadvantages of hard water

Answer 37

it is unfit for laundries not good for drinking purposes and not used in industrial purposes as it form a rusty boiler scale

Question 38

borax soution can be used to remove ?

Answer 38

coffee stains

Question 39

turpentine can used to remove ?

Answer 39

paint stains

Question 40

petrol can be used to remove?

Answer 40

grease stains