Difference between Amorphous and Crystalline solids

Difference between Amorphous and Crystalline solids

Property	Crystalline solids	Amorphous solids
Shape	Definite characteristic geometrical shape	Irregular shape
Melting point	Melt at a sharp and characteristic temperature	Gradually soften over a range of temperature
Cleavage property	When cut with a sharp edged tool, they split into two pieces and the newly generated surfaces are plain and smooth	When cut with a sharp edged tool, they cut into two pieces with irregular surfaces
Heat of fusion	They have a definite and characteristic heat of fusion	They do not have definite heat of fusion
Anisotropy	Anisotropic in nature	Isotropic in nature
Nature	True solids	Pseudo solids or super cooled liquids
arrangement of constituent particles	Long range order	Only short range order.

anisotropic and isotropic nature of solid

Crystalline solids are anisotropic in nature, that is, some of their physical properties like electrical resistance or refractive index show different values when measured along different directions in the same crystals. This arises from different arrangement of particles in different directions. This is illustrated in figure .

Since the arrangement of particles is different along different directions, the value of same physical property is found to be different along each direction.

Amorphous solids on the other hand are isotropic in nature. It is because there is no long range order in them and arrangement is irregular along all the directions. Therefore, value of any physical property would be same along any direction.

pseudo solids or super cooled liquids (why glass is called pseudo solids or super cooled liquids ?)

Like liquids, amorphous solids have a tendency to flow, though very slowly. Therefore, sometimes these are called pseudo solids or super cooled liquids. Glass panes fixed to windows or doors of old buildings are invariably found to be slightly thicker at the bottom than at the top. This is because the glass flows down very slowly and makes the bottom portion slightly thicker.

amorphous solid properties examples structure

An amorphous solid (Greek amorphos = no form) consists of particles of irregular shape. The arrangement of constituent particles (atoms, molecules or ions) in such a solid has only short range order. In such an arrangement, a regular and periodically repeating pattern is observed over short distances only. Such portions are scattered and in between the arrangement is disordered.

amorphous of structure

Glass, rubber and plastics are typical examples of amorphous solids.

crystalline solids properties structure examples

A crystalline solid usually consists of a large number of small crystals, each of them having a definite characteristic geometrical shape. In a crystal, the arrangement of constituent particles (atoms, molecules or ions) is ordered. It has long range order which means that there is a regular pattern of arrangement of particles which repeats itself periodically over the entire crystal. Sodium chloride and quartz are typical examples of crystalline solids.

               structure of crystalline solids

General Characteristics of Solid State

The following are the characteristic properties of the solid state:

(i) They have definite mass, volume and shape.

(ii) Intermolecular distances are short.

(iii) Intermolecular forces are strong.

(iv) Their constituent particles (atoms, molecules or ions) have fixed positions and can only oscillate about     their mean positions.

(v) They are incompressible and rigid.

Average speed of a particular airplane is 729.8mi/h. What's speed in m/s ?

Average speed of a particular airplane is 729.8mi/h. What's speed in m/s ?

Average speed pf plane in m/s  =

cancel out the values we get 

Average speed  = 729.8* 1909.36 / 60*60  m/s

                        = 326.25 m/s

Answer = 326.25 m/s

Average speed of particular airplane is 729.8 mi/h . What is the speed in m/s?

use the factor theorem to determine whether (x-3) is a factor of f(x)=x^4+12x^3+6x+27

use the factor theorem to determine whether (x-3) is a factor of f(x)=x^4+12x^3+6x+27

Answer

(x)=x  ⁴  given that x-3 is a factor of expression

use remainder theorem

put x  - 3  = 0

we get x = 3

plug 3 in place of x in the given value of f (x)

f(x)=x⁴+ 12x³ + 6x + 27

f(3)=(3)⁴+12(3)³+6(3)+27.

     = 81+ 324 + 18 + 27

     = 430

here 430 is not equal to 0 so that  Hence x -3 is not a factor of f(x)=x^4+12x^3+6x+27

A coffee cup calorimeter contains 0.0375 mol HCl dissolved in 1.50 x 10^2 mL of water at 20.51 C. When 1.75 g of solid zinc metal is placed in the calorimeter, the temperature rises to 29.02 C. Assume that no heat is lost to the surroundings.

A coffee cup calorimeter contains 0.0375 mol HCl dissolved in 1.50 x 10^2 mL of water at 20.51 C. When 1.75g of solid zinc metal is placed in the calorimeter, the temperature rises to 29.02 °C.  Assume that no heat is lost to the surroundings.

Write the balanced equation for the reaction that takes place in the calorimeter.  1pt

Balanced reaction

Zn (s)  + 2 HCl (aq) --> ZnCl₂(aq) + H2 (g)

Find the limiting reactant. Show your work. 2 pts.

Number of moles of Zn             = given mass of Zn / molar mass of Zn

                                                  = 1.75 g Zn / 65.3.9 g/mol

                                                  = 0.02676 moles Zn

In equation 1 mole of Zn react with 2 mol of HCl

Hence  0.02676 moles Zn react with        = 2  x 0.02676

                                                             = 0.05352 mol of HCl 

But required moles of HCl (0.05352 mol) > given moles (0.0375)

Hence HCl is limiting reagent

Find the amount of heat lost or gained by the calorimeter. Show your work. 2pts.

Formula of heat change, ∆T       = T₂ - T₁ = 29.02 - 20.51  = 8.51 ° C

Specific heat capacity for water , C = 4.184 J/g-C

Mass of water m                            = 1.50 x 10²  ml = 150 g  (for water 1 ml = 1 g )

Use formula of enthalpy change ∆H = m * C *∆T

Plug the values

                                               ∆H = 150 g  x 4.184 J/g-C  x 8.51 C

∆H = 5341 Joules         

Divide by 1000 to convert in kJ 

                                                ∆H = 5.34 KJ

Temperature is increasing so that it is a exothermic reaction

And for all exothermic reaction ∆H is always negative 
energy lost by reaction and gained by solution.  hence calorimeter gain this energy

 So final answer will ∆H = - 5.34 KJ

Which of the following pairs of linear equations are consistent/inconsistent? If consistent, obtain the solution graphically:

Which of the following pairs of linear equations are consistent/inconsistent? If consistent, obtain the solution graphically:

(i)              x + y = 5, 2x + 2y = 10

Convert the equation in form of 

a1x + b1y + c1 = 0  and a2x+ b2y + c2 = 0

We get

               x + y  -5 = 0, 2 x + 2 y  -10 = 0

Compare the equation with

              

We get

a1 = 1,            b1       = 1,                 and c1 = -5

a2 = 2             b2        = 2                   and c2 = - 10

                                    

 So we get 

                                  

Dependent and consistent  so it will have many solutions .

(ii)           x – y = 8, 3x – 3y = 16

Convert the equation in form of

a1x + b1y + c1 = 0  and a2x+ b2y + c2 = 0

We get

   x – y -8 = , 3x – 3y -16 = 0

Compare the equation with

                         

We get

a1 = 1,  b1     = - 1,              and c1 = - 8

a2 = 3  b2      =  - 3               and c2 = - 16

 

So we get 

  

So both lines are Inconsistent

(iii) 2x + y – 6 = 0, 4x – 2y – 4 = 0

Compare the equation with

              

We get

a1 = 2,            b1       =  1,                and c1 = - 6

a2 = 4             b2        =  - 2               and c2 = - 4

 

So we get 

So both lines are consistent

Solve the equations graphically

2x + y – 6 = 0,

Subtract 2x and add 6 both side we get

 y  = 6 – 2x

plug x = 1,2 and 3 we get

y         =  6 - 2 * 1      = 4

 y         = 6 -  2 * 2      = 2

y          =  6 -  2 * 3     = 0

X	1	2	3
y	4	2	0

 4 x – 2 y – 4 = 0

Divide by 2 we get

2 x – y - 2                  = 0 

Add y both side we get

2 x – 2            = y

or

y          = 2x – 2

plug x  = 1.2 and 3 we get

y          = 2 * 1 – 2      = 0

y          = 2 * 2 – 2      = 2

y          = 2 * 3 – 2      =  4

X	1	2	3
y	0	2	4

Answer x = 2 and y = 2

(iv) 2x – 2y – 2 = 0, 4x – 4y – 5 = 0

Compare the equation with

         

We get

a1 = 2,            b1       = - 2,              and c1 = - 2

a2 = 2             b2        =  - 2               and c2 = - 5

So both lines are Inconsistent