##### A sample of the male sex hormone testosterone, C19H28O2, contains....

 Chemistry Tutor: None Selected Time limit: 1 Day

A sample of the male sex hormone testosterone, C19H28O2, contains 7.04  1020 hydrogen atoms.

a)How many atoms of carbon does it contain?

(b) How many molecules of testosterone does it contain?

(c) How many moles of testosterone does it contain?

(d) What is the mass of this sample in grams?
Jul 23rd, 2015

DATA:

Number of hydrogen atoms in sample= 7.04*1020 atoms

Formula of testosterone = C19H28O2

Number of C atoms in sample=?

Total number of molecules of testosterone in sample=?

Number of moles of testosterone in sample=?

Mass of sample in grams=?

SOLUTION:
28 hydrogen atoms are present in 1 molecule of testosterone

7.04*1020 atoms will be present in (1*7.04*1020)/28

= 2.5142*1019 molecules of testosterone.

1 molecule of testosterone contains 19 C atoms

2.5142*1019 molecules of testosterone contain (19*2.5142*1019)/1

= 4.7771*1020 C atoms

6.02*1023molecules are present in 1 mol of testosterone

2.5142*1019 molecules will be present in (1*2.5142*1019)/6.02*1023

= 4.1764*10-5 mol of testosterone

Mass of testosterone sample= moles of testosterone *molecular mass of testosterone

= 4.1764*10-5 *168

= 7.0163*10-3g

Number of C atoms in sample=4.7771*1020 C atoms

Total number of molecules of testosterone in sample=2.5142*1019

Number of moles of testosterone in sample=4.1764*10-5 mol

Mass of sample in grams= 7.0163*10-3g

Jul 23rd, 2015

The only one i dont understand is the mass of the sample in grams. I got 0.0121 grams. Do you know what mistake I made?

Jul 24th, 2015

you either mistaken in molecular mass sum up or in moles.

Jul 24th, 2015

I multiplied 4.18e-5 moles times 288.47g (the molecular mass of the testosterone), so what should I have done?

Jul 24th, 2015

you have messed up in the molecular mass of testosterone. it is 168g/mol

Jul 24th, 2015

C19H28O2    is the formula

(12.01 x 19) + (1.01 x 28) + (16 x 2)

= 288.47...

Jul 24th, 2015

Im confused :(

Jul 24th, 2015

1.204*10^-2 g is the correct answer. your calculation is perfect. basically i messed up.

Jul 24th, 2015

Thats okay your still a great tutor 5 stars :)

Jul 24th, 2015

thank you and sorry for the inconvinience.

Jul 24th, 2015

Jul 24th, 2015

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Jul 23rd, 2015
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Jul 23rd, 2015
May 29th, 2017
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