Question

A student dissolves 10.2 g of sodium hydroxide (NaOH) in 250. g of water in a well-insulated open cup. He then observes the temperature of the water rise from 21.0 °C to 32.7 °C over the course of 3.7 minutes. Use this data, and any information you need from the ALEKS Data resource, to answer the questions below about this reaction: NAOH(s) → Na" (aq) + OH (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 3 significant digits. do Note for advanced students: Its 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? O endothermic O neither 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. kJ Calculate the reaction enthalpy AH per mole of NaOH. mol

Answer 1

A) The reaction is an exothermic reaction

B) 12.744 kJ

c) 49.976 KJ/mol . NaOH

Step-by-step explanation:

A) The reaction is an exothermic reaction

B) calculate the amount of heat that was released or absorbed by the reaction in this case. kJ

Assuming : specific heat of solution = specific heat of water = 4.186 J/g°C

mass of solution = 10.2 + 250 = 260.2 g

determine The heat released in the reaction

= mass of solution * specific heat of solution * temperature change

= 260.2 * 4.186 * ( 32.7 - 21 )

= 12.744 kJ

C) Calculate the reaction enthalpy ΔH per mole of NaOH. mol

Reaction enthalpy = - heat released / ( 10.2 /40 )

= - 12.744 / ( 10.2/40 ) = - 49.976 KJ/mol . NaOH