7. An alpha particle is_______
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0.259 52 . The fraction of empty space in a ccp cell is 0.259 52
Cubic closest packing is another name for <em>face centred cubic</em>.
Refer to the attached diagram of an fcc unit cell from <em>hemantmore</em>.
<h2>a) <em>Volume of atoms in unit cell </em></h2>
a. <em>Number of atoms in unit cell </em>
In an fcc lattice, there are eight atoms at the eight corners of the cube and one at the centre of each face
∴ No. of atoms
= 8 corners x (1/8 atom)/(1 corner) + 6 faces x (½ atom/1 face)
= 1 atom + 3 atoms = 4 atoms
b. <em>Volume of atoms </em>
Let <em>r</em> be the radius of an atom. Then
Volume of 1 atom = (4/3)π<em>r</em>^3
Total volume of atoms = 4 atoms × [(4/3)π<em>r</em>^3]/(1 atom) = (16/3)π<em>r</em>^3
<h2>b) <em>Volume of unit cell </em></h2>
The length of the diagonal AB is
AB = 4<em>r</em>
Let <em>a</em> be the edge length of the cube.
AB^2 = AC^^2 + BC^2
(4<em>r</em>)^2 = <em>a</em>^2 + <em>a</em>^2
16<em>r</em>^2= 2<em>a</em>^2
<em>a</em>^2 = 8<em>r</em>^2
<em>a</em> = <em>r</em>x8^½
<em>V</em> = <em>a</em>^3 = (<em>r</em>x8^½)^3 = 8<em>r</em>^3x8^½
<h2>c) <em>Fraction of occupied space</em> (packing efficiency, PE) </h2>
PE = Volume of atoms/Volume of cell = [(16/3)π<em>r</em>^3]/[ 8<em>r</em>^3x8^½]
= 2π/(3x8^½)
<h2>d) <em>Fraction of empty space </em></h2>
Fraction of empty space = 1 - PE = 1 - 2π/(3x8^½) = 1 – 0.740 480
= 0.259 52
Explanation:
According to Bronsted-Lowry an acid is defined as the specie which is able to donate hydrogen ions when dissolved in water.
For example,
On the other hand, bases are the species which are able to donate hydroxide ions when dissolved in water.
For example,
A specie which is able to accept a hydrogen atom and also able to donate a hydroxide ion will act as both acid and a base.
For example, is able to donate a hydroxide ion and simultaneously can accept a hydrogen ion.
In , the hydrogen atoms are strongly held together by the carbon atoms due to the small electronegativity difference between carbon and hydrogen atom. Hence, it will be a weak acid.
On the other hand, can loose a hydrogen atom or it can also gain a hydroxyl group. This is due to the electronegativity difference between oxygen and hydrogen atom.
Thus, we can conclude that following compounds are classified as follows.
- can be both acid and base
- very weak acid
- can be both acid and base