题目
题目

MUF0042 Chemistry Unit 2 - Semester 1, 2025

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Question textQ5 V2A chemical calibration is used to calibrate a calorimeter.A well insulated calorimeter containing 100 ml of water was calibrated by dissolving a known amount of sodium chloride in the calorimeter.The dissolution of sodium chloride in water can be represented by the equation:NaCl(s) +  aq [math: ⟶]\ce{ -> }  Na+(aq) + Cl‾(aq) [math: ΔH]\ce{ $\Delta H$ } = +3.90 kJ mol-1The temperature of the calorimeter was initially 18.00 oC. A sample of 2.55 g of sodium chloride was dissolved in the 100 mL and the temperature was recorded as 16.30 oC.Mr (NaCl) = 58.5 g mol-1The calibration factor of the calorimeter is Answer 1 Question 5[input] J oC-1(express your answer to 3 significant figures)

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Let's break down the data and compute the calibration factor step by step. - The dissolution enthalpy is given as ΔH = +3.90 kJ/mol for NaCl(s) → Na+(aq) + Cl−(aq). - The amount of NaCl dissolved is 2.55 g. Its molar amount is n = mass / M = 2.55 g / 58.5 g/mol = 0.0436 mol (to four significant figures). - The heat change for the dissolution process is q_rxn = n × ΔH = 0.0436 mol × 3.90 kJ/mol = 0.1700 kJ = 170 ......Login to view full explanation

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