Q155CP The human body excretes nitrogen... [FREE SOLUTION]

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Chapter 3: Q155CP (page 139)

The human body excretes nitrogen in the form of urea, NH₂CONH₂. The key biochemical step in urea formation is the reaction of water with arginine to produce urea and ornithine:
(a) What is the mass percent of nitrogen in urea, arginine, and ornithine? (b) How many grams of nitrogen can be excreted as urea when 135.2 g of ornithine is produced?

Short Answer

Expert verified

The mass percentage of nitrogen in urea as: 46.65% N in urea, 32.16% N in arginine and 21.2 % in ornithine.

There are 28.66 g Ncan be excreted as urea when 135.2 g or ornithine is produced.

Step by step solution

Calculating the mass percent of nitrogen in urea, arginine and ornithine

The mass percentage can be calculated as,

$M a s s % o f N = \frac{m o l e s o f N i n f o r m u l a 脳 m o l a r m a s s o f N}{m a s s o f 1 m o l o f c o m p o u n d} 脳 100 M a s s % o f N = \frac{2 m o l N 脳 \frac{14.01 g N}{1 m o l N}}{60.07 g C H_{4} N_{2} O} 脳 100 = 46.65 % N i n u r e a M a s s % o f N = \frac{2 m o l N 脳 \frac{14.01 g N}{1 m o l N}}{132.19 g C_{5} H_{12} N_{2} O_{2}} 脳 100 = 21.2 % N i n o r n i t h i n e$

Calculating the mass percent of N

On calculating the mass of urea,

$M a s s o f u r e a = 135.2 g C_{5} H_{12} N_{2} O_{2} 脳 \frac{1 m o l C_{5} H_{12} N_{2} O_{2}}{132.19 g C_{5} H_{12} N_{2} O_{2}} 脳 \frac{1 m o l C H_{4} N_{2} O}{1 m o l C_{5} H_{12} N_{2} O_{2}} 脳 \frac{60.07 g C H_{4} N_{2} O}{1 m o l C H_{4} N_{2} O} M a s s o f u r e a = 0.4665 脳 61.4378 g C H_{4} N_{2} O M a s s o f N = 0.4665 脳 61.4378 g C H_{4} N_{2} O = 28.66 g N$