200 mL of 0.2 M NaOH solution is prepared, then it is diluted to 0.1 M. Find the total change in enthalpy (in Joules).
Given: $Δ H_{so l u t i o n}$ (0.2 M) = –15 kJ/mol
$Δ H_{d i l u t i o n}$ (0.2 M to 0.1 M) = –3 kJ/mol

Question

200 mL of 0.2 M NaOH solution is prepared, then it is diluted to 0.1 M. Find the total change in enthalpy (in Joules).

Given: $Δ H_{so l u t i o n}$ (0.2 M) = –15 kJ/mol

$Δ H_{d i l u t i o n}$ (0.2 M to 0.1 M) = –3 kJ/mol

TestHub · Accepted Answer

Moles of NaOH: n = M × V = 0.2 × 0.2 = 0.04 m o l Heat of solution: q 1 ​ = 0.04 × ( − 15 ) = − 0.6 k J Heat of dilution: q 2 ​ = 0.04 × ( − 3 ) = − 0.12 k J Total enthalpy change: Δ H = q 1 ​ + q 2 ​ = − 0.6 k J + ( − 0.12 k J ) = − 0.72 k J = − 720 J

Chemistry - Thermochemistry Question with Solution | TestHub

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