An exothermal reaction is one which has a negative ?H value while an endothermal reaction is one which has a positive ?H value. Based on the consequences, the disintegration of K H tartrate has a ?H & A ; deg ; value of 3.89 *104. Therefore as 3.89 *104 & A ; gt ; 0, the disintegration of K H tartrate is endothermal, i.e. heat must be added to fade out the salt in H2O. This is farther supported by the negatively aslant graph above. It can be inferred from the graph that the higher the temperature, the greater the solubility of K H tartrate.
The spontaneousness of a reaction depends on the alteration in heat content ( ?H ) and entropy ( ?S ) , every bit good as on the absolute temperature. The alteration in the Gibbs free energy ( ?G ) can be used to find if a reaction is self-generated or non. Represented by the equation ?G & A ; deg ; = ?H & A ; deg ; – T?S & A ; deg ; , when ?G is negative, a procedure returns spontaneously in the forward way. When ?G is positive, the procedure returns spontaneously in contrary. When ?G is zero, the procedure is in equilibrium, with no net alteration taking topographic point over clip.
Therefore as the ?G & A ; deg ; calculated at both 10.0 & A ; deg ; C and 50.0 & A ; deg ; C are positive, it can be deduced that the disintegration of K H tartrate is non-spontaneous in the forward way at the temperatures tested ( 10.0 & A ; deg ; C to 50.0 & A ; deg ; C ) . The procedure nevertheless proceeds spontaneously in contrary at the mentioned temperatures. In fact, based on the consequences, the disintegration will merely be self-generated at 513.6K ( ?H & A ; deg ; / ?S & A ; deg ; ) and above.
Although both entropy and heat contents are maps of temperature, this experiment assumes that ?H & A ; deg ; and ?S & A ; deg ; make non alter significantly over the scope of temperatures used. This premise is valid over comparatively little scopes. In this experiment, the assorted measurings occur within a little scope of 40K. Therefore it is safe to presume that the values of ?H & A ; deg ; and ?S & A ; deg ; are comparatively invariant over the little alterations in temperature.
Many grounds could do the experimental value to differ with the literature value. Probably the most important beginning of mistake would be the inability to keep the several temperatures during the slow measure of filtrating the salt solution after heating/cooling. Gravity filtration was adopted in this experiment, and although the filter documents were fluted to promote rapid filtration, the procedure still spanned several proceedingss. During this clip, the temperature of the salt solution could hold easy deviated from the coveted temperatures towards room temperature. This could do unwanted recrystallization/dissolution of the salt, thereby, impacting the molar concentration of the filtrate. This restriction could be overcome by utilizing vacuum filtration to minimise such mistakes.
Besides the possible unwanted recrystallization/dissolution before filtering was over, recrystallization could besides happen in the filtrate before the 25mL aliquots were obtained. This would merely use to the samples that were experimented at temperatures above room temperature. As the filtrate cools, the salt would recrystalise, doing a alteration in homogeneousness and molar concentration of the filtrate. Although the protocol was to instantly aliquot 25mL after filtration, the clip for the filtrate to make at least 25mL was sufficient plenty for important chilling of the solution, with the big surface country of the solution filtrating dropwise and the contact with the cool conelike flask. A possible solution to this job is to heat the filtrate once more after filtration before aliquoting to guarantee all the salts that may hold recrystalised dissolve. However, the warming should be soft to forestall important lost of dissolver and prevent alteration in molar concentration.
Another beginning of mistake would be the premise that the molar concentration of the given NaOH solution is accurate. Alkaline solutions such as NaOH absorb C dioxide from the ambiance harmonizing to the reaction: CO2 + 2OH- – + CO32- + H2O. Since hydroxide ion is consumed by this reaction, the concentration of the Na hydrated oxide solution will be changed. Therefore the precise concentration of the NaOH solution may non be the value that what was stated on the bottle, particularly if the solution was prepared long before the experiment was conducted. Standardization of the NaOH solution should be done merely before the experiment is conducted.
Although in this experiment, the molar concentration of the provided NaOH solution was assumed to be accurate and no farther standardisation was done, safeguards were taken to protect the solution from the C dioxide that is ever present in the ambiance. As during titration, the NaOH solution in the buret will be exposed to air, the buret used was prepared for usage merely when it was needed, and fresh Na hydrated oxide should be added if it.
The initial stairss of the process was to obtain about 200ml of NaOH solution from the stock bottle. To obtain higher truth though, the NaOH taken from the stock bottle should non be more than what is needed for one titration. More NaOH solution should be taken from the stock bottle when needed.
Other safeguards were besides taken during the experiment to cut down taint. Apparatus were conscientiously cleaned and rinsed with solutions that they were to incorporate before usage. The experiment was besides carefully done to forestall loss of stuff through spillage, sprinkling or spilling.
This experiment successfully demonstrated the relationships between province maps, including information and heat content, free energy, spontaneousness, and equilibrium invariables. Since ?H & A ; deg ; and ?S & A ; deg ; were both positive, the disintegration of K H tartrate was self-generated at high temperatures. This means that the K H tartrate needed energy from the milieus to fade out. The contrary procedure nevertheless, is self-generated.
A important per centum mistake was obtained by comparing of the obtained solubility merchandise invariable with the literature value. Although safeguards were taken to guarantee truth, such an mistake proves that solubility merchandise invariables are highly hard to obtain by experimentation because of restrictions of the experiment and the necessity to place all chemical species and procedures present in the chemical system used to obtain the values.