CHEM1305 Lab 3-1 and 3-10 Report PDF

Preview

Summary

CHEM1305 Lab 3-1 and 3-10 Report...

Description

CHEM1305.300 Marlys Baldwin September 12, 2021

VCL: 3-1 Endothermic vs. Exothermic, and 3-10 Heat of Reaction: NaOH(aq) + HCl(aq) Data and Post-lab Questions 3-1 Mixture NaCl(s) + H2O(l) NaNO3(s) + H2O(l) NaCH3COO(s) + H2O(l)

T1 25.01 25.01 25.00

T2 24.99 24.02 25.93

ΔT (T2-T1) 0.02 0.01 0.92

Endo- or exothermic? Endo (+) Endo (+) Exo (-)

1) Calculate ΔT (T2-T1) for each mixture and record it in the data table. 2) An endothermic process absorbs heat and an exothermic process gives off heat. Identify each process in the table as endothermic or exothermic. 3) What is the ΔT sign for an endothermic reaction? 4) Which solution(s) had little or no change in temperature? Nacl + H2O Data and Post-lab Questions 3-10

o

Initial temperature ( C) Final temperature (oC)

NaOH/HCl 25.01 31.06

1) Is the observed reaction endothermic or exothermic? What will be the sign of ΔHrxn? (rxn stands for reaction)

Endothermic (+) 2) Calculate the change in temperature, ΔT. Record your results in the Results table below. Although your temperature was recorded in oC, the ΔT is the same in Kelvin. 3) Calculate the mass of the reaction mixture in the calorimeter. (To do this, first determine the total volume of the solution, acid + base, and assume that the density of the new solution is the same as that of pure water, 1.0 g/mL.) Record your results in the Results table. 4) Calculate the total heat released in the reaction, assuming that the specific heat capacity of the solution is the same as that of pure water, 4.184 J/K*g. Record the results in the Results table. The heat of reaction (q) is equal to mCΔT, where m = mass, C = specific heat capacity, and ΔT = change in temperature, Tfinal-Tinitial. 5) Calculate the number of moles of NaOH used in the reaction by multiplying the volume of NaOH times the molarity (1.000 mol/L). Record the results in the Results table. 6) Calculate ΔHrxn in kJ/mol, of NaOH for the reaction and record the results in the Results table. Make sure the sign of ΔHrxn is correct. (Negative ΔHrxn is used for exothermic reactions; positive ΔHrxn is used for endothermic reactions.)

Mass of Rxn Mixture 200g

ΔT

6.13

Total Heat Released, q (q = mCΔT) 5.13 K/J

Mole NaOH

0.01

ΔHrxn/mol

-51.3 (Exo)...