Question

Complete questions 2-4 using data from table and the answer from question 1

Measuring Enthalpy Results

NaHCO₃(s) + HC₂H₃O₂(aq) à NaC₂H₃O₂(aq) + H₂O(l) + CO₂(g)     

	Trial 1	Trial 2
mass of baking soda(NaHCO3) added	5.4g	5.4g
mass of vinegar added	20ml	20ml
Final temperature, tf	16.7C	16.7°C
Initial temperature, ti	21.1°C	21.1°C
Change in temperature, ∆t	4.4°C	4.4°C
q (water) = mwCwTw	467.6 J	467.6 J
q(reaction)	-467.6 J	-467.6 J
moles of NaHCO3	.0642	.0642
ΔH (kJ/mol)	-7.27448 kJ/mol	-7.27448 kJ/mol

Complete questions 2-4 using data from table and the answer from question 1

Q.1 – Using the reaction below, and the enthalpy of formation values, determine the theoretical enthalpy for the reaction from the equation ∆H = ∑H_fProducts - ∑H_fReactamts

NaHCO₃(s)       + HC₂H₃O₂(aq) à Na⁺_(aq) + C₂H₃O₂^-_(aq) + H₂O_(l) + CO_2(g)     

baking soda         acetic acid                    

H_f­ values in kJ/mol

HC₂H₃O₂(aq)   -486

NaHCO₃(s)       -950.8

Na⁺(aq)            -240.1

C₂H₃O₂^-_(aq)       -486

H₂O_(l)               -393.5

CO_2(g)               -285.8

ANSWER = 31.4 kJ/mol

Q.2 Compare the value (+,-) in in your lab with the value determined in Q.1.   Does the reaction correctly match the definition of exothermic or endothermic? How does the temperature change in the water correlate to the change in the reaction?

Q.3 Compare the number in your lab vs Q.1.   What was the size of the error in this experiment?

%error = Hf value - experiment value * 100 =         

                           H_f value

Q.4 What are some errors in your setup that could have caused this error? What pieces of equipment would result in a better final heat measurement? Be specific.

Answer 1