0.240 g CaCO3 0.374 g BaSO4 0.206 g NH3 FW 156

0.240 g CaCO3 0.374 g BaSO4 0.206 g NH3 FW 156

 

 

A compound containing Ca, C, N and S was subjected

to quantitative analysis and formula mass determination.

A 0.375 g of this compound was mixed with Na2CO3

to convert all Ca into 0.240 g CaCO3.

A 0.125 g sample of compound was carried through

a series of reactions until all its S was changed into

SO4^2- and precipitated as 0.374 g of BaSO4.

A 0.946 g sample was processed to liberated

all of its N as NH3 and 0.206 g NH3 was obtained.

The formula mass was found to be 156.

Determine the empirical and molecular formula of the compound.

 

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> CaCO3의 몰질량 = 100.09 g/mol

> Ca의 몰질량 = 40.08 g/mol

 

질량비로 0.240 g CaCO3에 들어있는 Ca의 질량을 계산하면,

( 참고: 질량비로 계산 https://ywpop.tistory.com/5078 )

 

CaCO3 : Ca = 100.09 : 40.08 = 0.240 g : ? g

 

? = 40.08 × 0.240 / 100.09 = 0.0961 g Ca

 

 

 

0.375 g 시료 중 Ca의 질량 백분율을 계산하면,

(0.0961 g / 0.375 g) × 100 = 25.6% Ca

( 참고: 조성 백분율 https://ywpop.tistory.com/12958 )

 

 

 

 

> BaSO4의 몰질량 = 233.39 g/mol

> S의 몰질량 = 32.07 g/mol

 

BaSO4 : S = 233.39 : 32.07 = 0.374 g : ? g

 

? = 32.07 × 0.374 / 233.39 = 0.0514 g S

 

(0.0514 / 0.125) × 100 = 41.1% S

 

 

 

> NH3의 몰질량 = 17.03 g/mol

> N의 몰질량 = 14.01 g/mol

 

NH3 : N = 17.03 : 14.01 = 0.206 g : ? g

 

? = 14.01 × 0.206 / 17.03 = 0.169 g N

 

(0.169 / 0.946) × 100 = 17.9% N

 

 

 

시료 중 C의 질량 백분율을 계산하면,

100 – (25.6 + 41.1 + 17.9) = 15.4% C

 

 

 

시료의 질량 = 100 g 이라 가정하면,

시료의 질량 백분율 값 = 시료의 질량 값

( 참고: 원소분석 https://ywpop.tistory.com/64 )

 

 

 

각 성분의 몰수를 계산하면,

> Ca의 몰수 = 25.6 g / (40.08 g/mol) = 0.639 mol

( 참고 https://ywpop.tistory.com/7738 )

 

> C의 몰수 = 15.4 / 12.01 = 1.28 mol

> N의 몰수 = 17.9 / 14.01 = 1.28 mol

> S의 몰수 = 41.1 / 32.07 = 1.28 mol

 

 

 

몰수의 가장 작은 정수비를 계산하면,

Ca : C : N : S = 0.639 : 1.28 : 1.28 : 1.28

= 0.639/0.639 : 1.28/0.639 : 1.28/0.639 : 1.28/0.639

= 1 : 2 : 2 : 2

---> 실험식 = Ca C2 N2 S2

---> 실험식량

= (40.08) + 2(12.01) + 2(14.01) + 2(32.07) = 156.26

 

 

 

실험식량 ≒ 화학식량 이므로,

실험식 = 분자식 = CaC2N2S2

 

 

 

답: 실험식 = 분자식 = CaC2N2S2

 

 

 

 

[키워드] Ca C N S 화합물 분석, Ca C N S 화합물 실험식

0.16 g CaCO3 0.344 g of BaSO4 0.155 g NH3 FW 156

A compound containing Ca, C, N and S was subjected

to quantitative analysis and formula mass determination.

A 0.25 g of this compound was mixed with Na2CO3

to convert all Ca into 0.16 g CaCO3.

A 0.115 g sample of compound was carried through

a series of reactions until all its S was changed into

SO4^2- and precipitated as 0.344 g of BaSO4.

A 0.712 g sample was processed to liberated

all of its N as NH3 and 0.155 g NH3 was obtained.

The formula mass was found to be 156.

Determine the empirical and molecular formula of the compound.