Question

10A-7 10A CHEMICAL EQUATIONS: ENERGY RELATIONSHIPS NAME 1315 Section Pre-Lab Assignment NOTE: The data used here are for illustrative purposes. The data you obtain will be different. A DETERMINATION OF CALORIMETER CONSTANT HCl(aq) + NaOH(aq) NaCl(aq) + H2O (1) AH = -56.1 kJ/mol Record the molarity and volume of stock HCl solution used in this reaction and the initial, Ti, and final temperatures, T2. Report the temperature change for this reaction. STO EXAMPLE: used 25.0 mL of 2.31 M HCI; T. is 22.9 °C; Tis 35.4 °C; and AT is 12.5°C. PRACTICE: used 25.0 mL of 2.07 M HCI; T. is 24.3°C; T, is 35.9°C. and S . Use the above data in conjunction with the given thermochemical equation to calculate the amount of heat produced in this reaction. EXAMPLE: -3.240 kJ. PRACTICE: Determine K for the calorimeter. EXAMPLE: 0.259 kJ/°C PRACTICE: B. DETERMINATION OF AH FOR THE REACTION Mg (s) + 2HCl(aq) MgCl, (aq) + H2 (9) Record mass and temperature data, and report the temperature change for this reaction. EXAMPLE: the magnesium weighs 0.149 g: Tis 22.6°C; Tis 36.4°C, and aT is 13.8 °C PRACTICE: the magnesium weighs 0.153 g: Tis 24.3 °C, T, is 38.5°C.dris 14.2 Use the above results to determine the enthalpy change, AH, for this reaction EXAMPLE: -583 kJ/mol Mg. PRACTICE

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Answer 1

(A) Determination of of Calooimeler constant. cal ooimeter T2 = 35.9 degree C Ty : 24.3 degree C So, AT = (1, -T.) - (35.9 -243) : 11.6 degree Amount of heat produced. 25 ml 2.07 M HCl. (25*2.07) 51.75m molhcl : 0.05115 motel so total heat produced 0.05175 x ( -56.1) = 2.903 kJ (-56.1 = 3H given) k of calorimeter 25 ml 2.07m Hel is equal to . (25 x 2.07) : 51.75m mol HCl = 015175 mol Hol. for 0.051 75 mol Hill change in T = 116 so, ford mol Hel change in T- 11.6 0.5175 : 224.1.54

= 56.1 -0.25027 k5/ degree C 224.15y =0,25027 kilde B) Determination of SH *2 = 38.5 degree c. Tis 243 degreece ST. 72-7, =1462 degree C . . mod Mg = 24.3059 mg • 1539 mg = (6153/241305) moling DH = 615,947 / mding