CHO 1.200 g sample 3.516 g CO2 1.007 g H2O

CHO 1.200 g sample 3.516 g CO2 1.007 g H2O

 

 

Anabolic steroids are sometimes used illegally

by athletes to increase muscle strength.

A forensic chemist analyzes some tablets

suspected of being a popular steroid.

He determines the substance contains only C, H and O

and has a molar mass of 300.42 g/mol.

When a 1.200 g sample is subjected to combustion analysis,

3.516 g of CO2 and 1.007 g H2O are collected.

a) What is the empirical formula of the unknown substance in the tablets?

b) What is the molecular formula of the unknown substance in the tablets?

 

---------------------------------------------------

 

▶ 참고: 원소분석 [ https://ywpop.tistory.com/64 ]

▶ 참고: CHO 연소분석 [ https://ywpop.tistory.com/2854 ]

▶ 참고: CHN 연소분석 [ https://ywpop.tistory.com/3116 ]

 

 

 

각 성분의 질량을 계산하면,

C의 질량 = 3.516 g × (12 / 44) = 0.95891 g

H의 질량 = 1.007 g × (2 / 18) = 0.11189 g

O의 질량 = 1.200 – (0.95891 + 0.11189) = 0.1292 g

 

 

 

각 성분의 몰수를 계산하면,

C의 몰수 = 0.95891 g / (12 g/mol) = 0.07991 mol

H의 몰수 = 0.11189 / 1 = 0.11189 mol

O의 몰수 = 0.1292 / 16 = 0.008075 mol

 

 

 

몰수의 가장 작은 정수비를 계산하면

C : H : O = 0.07991 : 0.11189 : 0.008075

= 0.07991/0.008075 : 0.11189/0.008075 : 0.008075/0.008075

= 9.896 : 13.86 : 1

≒ 10 : 14 : 1

---> 실험식 = C10 H14 O

---> 실험식량 = 10(12) + 14(1) + (16) = 150

 

 

 

분자량 / 실험식량 = 300.42 / 150 ≒ 2 = n

 

 

 

분자식 = n(실험식) = 2(C10 H14 O) = C20 H28 O2

 

 

 

답: 실험식 = C10H14O, 분자식 = C20H28O2

 

 

 

 

[키워드] 스테로이드 기준문서, CHO 1200 g sample 3516 g CO2 1007 g H2O