1.0 M HCI 50 mL + 1.0 M NaOH 50 mL, 21.0 to 27.5℃

1.0 M HCI 50 mL + 1.0 M NaOH 50 mL, 21.0 to 27.5℃

 

 

When a student mixes 50 mL of 1.0 M HCI and

50 mL of 1.0 M NaOH in a coffee-cup calorimeter,

the temperature of the resultant solution

increases from 21.0℃ to 27.5℃.

Calculate the enthalpy change(ΔH) for the reaction in kJ/mol HCl.

Assuming that the calorimeter loses only a negligible quantitiy of heat,

that the total volume of the solution is 100 mL, that its density is 1.0 g/mL,

and that its specific heat is 4.18 J/g•K.

 

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▶ 참고: 산-염기 중화반응과 중화열

[ https://ywpop.tistory.com/3925 ]

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q = C m Δt

( 참고 https://ywpop.tistory.com/2897 )

 

= (4.18 J/g•℃) (100 g) (27.5 – 21.0℃)

= (4.18) (100) (27.5 – 21.0)

= 2717 J

= 2.717 kJ

---> 열량계가 흡수한 열

= –2.717 kJ

---> 반응계가 방출한 열

 

 

 

1.0 M HCI 50 mL에 들어있는 HCl의 몰수를 계산하면,

(1.0 mol/L) (50/1000 L) = 0.05 mol HCl

 

 

 

HCl의 몰당 중화열을 계산하면,

–2.717 kJ / 0.05 mol

= –54.34 kJ/mol

 

 

 

답: ΔH = –54.34 kJ/mol

 

 

 

 

[참고] +q(열량계) = –q(반응)

---> ΔH = –q_rxn

 

 

 

 

[키워드] HCl + NaOH 중화열 기준, HCl + NaOH 중화열 계산 기준, ΔH = -q_rxn dic, ΔH –q_rxn dic