IldIIIC Prelaboratory Assignment: Enthalpy of Neutralization 1. 50.0 ml of 0.180
ID: 560678 • Letter: I
Question
IldIIIC Prelaboratory Assignment: Enthalpy of Neutralization 1. 50.0 ml of 0.180 M sodium hydroxide solution is added to 50 ml of 0.200 M lactic acid solution. The reaction goes to completion. It can be written CH, CHOHCO,H+ OH + CH, CHOHCO, +H,0. a. What is the limiting reactant. How many moles of it were used? b. The system can be regarded as 100 g of water, C = 4.184 J·K-1.g. Calculate the heat capacity of the system. c. The initial temperature of the system is 22.47 °C; the final temperature is 23.67 °C. Calculate the amount of heat absorbed by the system. d. Calculate the amount of heat released by the reaction. e. Calculate the molar enthalpy of neutralization for lactic acid. Write chemical profiles for acetic acid, hydrochloric acid, and sulfuric acid. Include hazard formation.Explanation / Answer
Q1
a)
limiting reactant:
mol of acid = MV = 0.2*50*10^-3 = 0.01
mol of base = MV = 0.18*50*10^-3 = 0.009
therefore, base is limting reaction, since it is less
NaOH
0.009 mol will react
b)
Heat Capacity*dT = mass of water * Cp water * dT
Cp = 100*4.184 = 418.4 J/g
c)
dT = 23.67-22.47 = 1.2
now...
Q = C*dT = 418.4*1.2
Q = 502.08 J
d
heat released by reaction = 502.08 J
e
HRxn = -Qrxn/n = -502.08 / 0.009 = -55786.66 = -55.7 kJ/mol