Question

A student dissolves 10.3 g of sodium chloride (NaCl) in 250. g of water in a well-insulated open cup. She then observes the temperature of the water fall from 22.0°C to 21.5°C over the course of 4.4 minutes. Use this data, and any information you need from the ALEKS Data resource, to answer the questions below about this reaction: NaCl(s) - Na (aq) + Cl" (aq) You can make any reasonable assumptions about the physical properties of the solution. Be sure answers you calculate using measured data are rounded to 1 significant digit. Note for advanced students: it's possible the student did not do the experiment carefully, and the values you calculate may not be the same as the known and published values for this reaction. O exothermic Is this reaction exothermic, endothermic, or neither? endothermic neither x 5 ? If you said the reaction was exothermic or endothermic, calculate the amount of heat that was released or absorbed by the reaction in this case. Ik Calculate the reaction enthalpy AH per mole of Naci. 0-

Answer 1

Sinice temperature of water means heat is taken away that some heat is used in So if reaction is taking heat it decreases , et from water and reaction. is endothermic reaction AY Endothermic reaction 4.184 Ilgm.°c weight of water = 250 gm Specific heat of wale = mcRAT = 250 x 4.1848 (21.5-22) Heat released = Q = by water Q = -523 J = -Q reaction = 523J Heat absorbed by 10.3 gm of Nac dissolved = cy weight 10.3 - Nach = 0.176 mo 38.5 523 2971.6 J moL on a = 523 = 2971. 6 I on- O. 176 An- 2.97 kJ/mol