어는점내림. 7.40 g MgCl2 + 110 g water

어는점내림. 7.40 g MgCl2 + 110 g water

 

 

What is the freezing point in ℃ of a solution

prepared by dissolving 7.40 g of MgCl2 in 110 g of water?

The value of Kf for water is 1.86 ℃/m,

and the van't Hoff factor for MgCl2 is i = 2.7

 

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MgCl2의 몰질량 = 95.21 g/mol 이므로,

7.40 g / (95.21 g/mol) = 0.0777 mol MgCl2

( 참고 https://ywpop.tistory.com/7738 )

 

 

 

몰랄농도 = 용질 mol수 / 용매 kg수

( 참고 https://ywpop.tistory.com/2667 )

 

= 0.0777 mol / 0.110 kg

= 0.7064 mol/kg

 

 

 

ΔTf = i × Kf × m

( i = van't Hoff 인자 )

( 참고 https://ywpop.tistory.com/1920 )

 

= (2.7) (1.86) (0.7064)

= 3.55℃

 

 

 

순수한 물의 어는점 = 0℃ 이므로,

답: -3.55℃

 

 

 

 

[키워드] MgCl2 용액의 총괄성 기준문서

 

 

 

 

> What is the freezing point in ℃ of a solution

prepared by dissolving 4.00 g of MgCl2 in 110 g of water?

 

> What is the freezing point in ℃ of a solution

prepared by dissolving 7.20 g of MgCl2 in 110 g of water?