Question

The natural abundances of elements in the human body, expressed as percent by mass, are: oxygen (O),65 percent; carbon (C), 18 percent; hydrogen (H), 10 percent; nitrogen (N), 3 percent; calcium (Ca), 1.6 percent; phosphorus (P), 1.2 percent; all other elements, 1.2 percent. Calculate the mass in grams of each element in the body of a 62-kg person.

Answer 1

Answer:

The mass in grams of each element in the body of 62 Kg are

Oxygen               40300 g

Carbon                11160 g

Hydrogen            6200 g

Nitrogen              1860 g

Calcium                992 g

Phosphorus         744 g

Other elements   744 g

It is possible to check it adding all the components, the total is 62000 g.  

Explanation:

Firstly, we have a total mass of 62 Kg and the composition as a percentage of each component.

                            Percentage ( %)

Oxygen               65.0

Carbon               18.0

Hydrogen            10.0

Nitrogen              3.0

Calcium               1.6

Phosphorus         1.2

Other elements   1.2

Taking the definition of a percentage as part of hundred total, each percentage can be expressed as a decimal number. We should divide the percentage with 100 of total. For example: Oxygen 65%, it means 65/100 = 0.65. So, Oxygen is 0.65 in decimal numbers. We do the same for each component.

                           Percentage ( %)      Decimal number

Oxygen               65.0                         65/100 = 0.65

Carbon               18.0                           18/100 = 0.18

Hydrogen            10.0                         10/100 = 0.10

Nitrogen              3.0                           3/100 = 0.03

Calcium               1.6                           1.6/100 = 0.016

Phosphorus         1.2                           1.2/100 = 0.012

Other elements   1.2                           1.2/100 = 0.012

Finally. We can multiply decimal number of each component taking the total. 1 Kg is equivalent to 1000 g.

So, 62 Kg = 62 * 1000 g = 62000 g

After that we get the mass in grams of each element, by multiplying 62000 g and the decimal number of each component as follows:

                           Percentage ( %)      Decimal number      Mass in grams (g)        

Oxygen               65.0                         65/100 = 0.65         0.65*62000=40300

Carbon               18.0                           18/100 = 0.18         0.18*62000=  11160

Hydrogen            10.0                         10/100 = 0.10         0.10*62000=   6200

Nitrogen              3.0                           3/100 = 0.03          0.03*62000= 1860

Calcium               1.6                           1.6/100 = 0.016        0.016*62000= 992

Phosphorus         1.2                           1.2/100 = 0.012        0.012*62000=744

Other elements   1.2                           1.2/100 = 0.012        0.012*62000=744