[Donald A. McQuarrie, John D. Simon] Physical Chem(BookZZ.org)
1279 pág.

[Donald A. McQuarrie, John D. Simon] Physical Chem(BookZZ.org)


DisciplinaFísico-química I6.510 materiais97.894 seguidores
Pré-visualização50 páginas
a n d i m a g i n a r y p a r t s o f t h e f o l l o w i n g q u a n t i t i e s : 
a . ( 2 - i )
3 
b . e " i / 2 
c . e - 2 + i n / 2 
d . ( . J 2 + 2 i ) e - i n / l 
A - 2 . I f z = x + 2 i y , t h e n f i n d 
a . R e ( z * ) 
b . R e ( z
2
) 
c . l m ( z
2
) d . R e ( z z * ) 
e . I m ( z z * ) 
A - 3 . E x p r e s s t h e f o l l o w i n g c o m p l e x n u m b e r s i n t h e f o r m r e ; e : 
a . 6 i b . 4 - . J 2 i 
c . - 1 - 2 i 
d . n + e i 
A - 4 . E x p r e s s t h e f o l l o w i n g c o m p l e x n u m b e r s i n t h e f o r m x + i y : 
a . e " f 4 i b . 6 e 2 n i / 3 
c . e - ( r r / 4 ) i + l n 2 
d . e - 2 n i + e 4 n i 
A - 5 . P r o v e t h a t e ; " = - 1 . C o m m e n t o n t h e n a t u r e o f t h e n u m b e r s i n t h i s r e l a t i o n . 
A - 6 . S h o w t h a t 
a n d t h a t 
c o s e = e i 8 + e - i 8 
2 
s i n e = e ; e - e - ; e 
2 i 
A - 7 . U s e E q u a t i o n A . 7 t o d e r i v e 
z n = r n ( c o s e + i s i n e ) " = r " ( c o s n e + i s i n n e ) 
a n d f r o m t h i s , t h e f o r m u l a o f D e M o i v r e : 
( c a s e + i s i n e ) " = c o s n e + i s i n n e 
A - 8 . U s e t h e f o r m u l a o f D e M o i v r e , w h i c h i s g i v e n i n P r o b l e m A - 7 , t o d e r i v e t h e t r i g o n o m e t r i c 
i d e n t i t i e s 
c o s 2 e = c o s
2 
e - s i n
2 
e 
s i n 2 e = 2 s i n e c o s e 
c o s 3 e = c o s
3 
e - 3 c o s e s i n
2 
e 
= 4 c o s
3 
e - 3 c o s e 
s i n 3 e = 3 c o s
2 
e s i n e - s i n
3 
e 
= 3 s i n e - 4 s i n
3 
e 
3 5 
36 MathChapter A I C 0 M P L EX N U M B E R 5 
A-9. Consider the set of functions 
1 . A. 
<t> (¢) = -e'm&quot;' 
m ~ 
First show that 
Now show that 
m=0,±1,±2, 
for all value of m =I= 0 
m=O 
m =I= n 
m=n 
A-1 0. This problem offers a derivation of Euler's formula. Start with 
j(e) = ln(cose + i sine) 
Show that 
df . 
-=l de 
Now integrate both sides of Equation 2 to obtain 
j(e) = ln(cose + i sine)= ie + c 
(1) 
(2) 
(3) 
where c is a constant of integration. Show that c = 0 and then exponentiate Equation 3 to 
obtain Euler's formula. 
A-11. We have seen that both the exponential and the natural logarithm functions (Problem 
A-10) can be extended to include complex arguments. This is generally true of most 
functions. Using Euler's formula and assuming that x represents a real number, show that 
cos ix and -i sin ix are equivalent to real functions of the real variable x. These functions 
are defined as the hyperbolic cosine and hyperbolic sine functions, cosh x and sinh x, 
respectively. Sketch these functions. Do they oscillate like sin x and cos x? Now show that 
sinh ix = i sin x and that cosh ix = cos x. 
A-12. Evaluate i;. 
A-13. The equation x 2 = 1 has two distinct roots, x = ± 1. The equation xN = l has N distinct 
roots, called the N roots of unity. This problem shows how to find the N roots of unity. We 
shall see that some of the roots turn out to be complex, so let's write the equation as zN = 1. 
Now let z = re;e and obtain rN e;Ne = 1. Show that this must be equivalent to eiNB = 1, or 
cos N e + i sin N e = 1 
Now argue that Ne = 2:n:n, where n has theN distinct values 0, 1, 2, ... , N- 1 or that 
the N roots of units are given by 
z = e2rrin/N n = 0, 1, 2, ... , N- 1 
P r o b l e m s 
S h o w t h a t w e o b t a i n z = 1 a n d z = ± 1 , f o r N = 1 a n d N = 2 , r e s p e c t i v e l y . N o w s h o w 
t h a t 
z = 1 _ 1 . . J 3 
, -2 + 1 -
2 ' 
a n d 
1 0 y ' 3 
- - - 1 -
2 2 
f o r N = 3 . S h o w t h a t e a c h o f t h e s e r o o t s i s o f u n i t m a g n i t u d e . P l o t t h e s e t h r e e r o o t s i n t h e 
c o m p l e x p l a n e . N o w s h o w t h a t z = 1 , i , - 1 , a n d - i f o r N = 4 a n d t h a t 
1 y ' 3 
z = 1 , - 1 , - ± i - , a n d 
2 2 
_ ! ± . . J 3 
2 1 -
2 
f o r N = 6 . P l o t t h e f o u r r o o t s f o r N = 4 a n d t h e s i x r o o t s f o r N = 6 i n t h e c o m p l e x p l a n e . 
C o m p a r e t h e p l o t s f o r N = 3 , N = 4 , a n d N = 6 . D o y o u s e e a p a t t e r n ? 
A - 1 4 . U s i n g t h e r e s u l t s o f P r o b l e m A - 1 3 , f i n d t h e t h r e e d i s t i n c t r o o t s o f x
3 
= 8 . 
3 7 
I 
Louis de Broglie was born on August 15, 1892 in Dieppe, France, into an aristocratic family 
and died in 1987. He studied history as an undergraduate in the early 1910s, but his interest 
turned to science as a result of his working with his older brother, Maurice, who had built 
his own private laboratory for X-ray research. de Broglie took up his formal studies in physics 
after World War I, receiving his Dr. Sc. from the University of Paris in 1924. His dissertation 
was on the wavelike properties of matter, a highly controversial and original proposal at 
that time. Using the special theory of relativity, de Broglie postulated that material particles 
should exhibit wavelike properties under certain conditions, just as radiation was known 
to exhibit particlelike properties. After receiving his Ph.D., he remained as a free lecturer 
at the Sorbonne and later was appointed professor of theoretical physics at the new Henri 
Poincare Institute. He was professor of theoretical physics at the University of Paris from 1937 
until his retirement in 1962. The wavelike properties he postulated were later demonstrated 
experimentally and are now exploited as a basis of the electron microscope. de Broglie spent 
the later part of his career trying to obtain a causal interpretation of the wave mechanics to 
replace the probabilistic theories. He was awarded the Nobel Prize for physics in 1929 &quot;for his 
discovery of the wave nature of electrons.&quot; 
C H A P T E R 2 
T h e C l a s s i c a l W a v e E q u a t i o n 
I n 1 9 2 5 , E r w i n S c h r o d i n g e r a n d W e r n e r H e i s e n b e r g i n d e p e n d e n t l y f o r m u l a t e d a g e n e r a l 
q u a n t u m t h e o r y . A t f i r s t s i g h t , t h e t w o m e t h o d s a p p e a r e d d i f f e r e n t b e c a u s e H e i s e n b e r g ' s 
m e t h o d i s f o r m u l a t e d i n t e r m s o f m a t r i c e s , w h e r e a s S c h r 6 d i n g e r ' s m e t h o d i s f o r m u l a t e d 
i n t e r m s o f p a r t i a l d i f f e r e n t i a l e q u a t i o n s . J u s t a y e a r l a t e r , h o w e v e r , S c h r o d i n g e r s h o w e d 
t h a t t h e t w o f o r m u l a t i o n s a r e m a t h e m a t i c a l l y e q u i v a l e n t . B e c a u s e m o s t s t u d e n t s o f 
p h y s i c a l c h e m i s t r y a r e n o t f a m i l i a r w i t h m a t r i x a l g e b r a , q u a n t u m t h e o r y i s c u s t o m a r i l y 
p r e s e n t e d a c c o r d i n g t o S c h r 6 d i n g e r ' s f o r m u l a t i o n , t h e c e n t r a l f e a t u r e o f w h i c h i s a 
p a r t i a l d i f f e r e n t i a l e q u a t i o n n o w k n o w n a s t h e S c h r o d i n g e r e q u a t i o n . P a r t i a l d i f f e r e n t i a l 
e q u a t i o n s m a y s o u n d n o m o r e c o m f o r t i n g t h a n m a t r i x a l g e b r a , b u t f o r t u n a t e l y w e 
r e q u i r e o n l y e l e m e n t a r y c a l c u l u s t o t r e a t t h e p r o b l e m s i n t h i s b o o k . T h e w a v e e q