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17 Nov 2019
What effect would poor circulation of the melting point bath liquid have on the observed melting point? What is the effect of an insoluble impurity, such as sodium sulfate, on the observed melting point of a compound? Three test tubes, labeled A, B, and C, contain substances with approximately the same melting points. How could you prove that the tubes contain three different chemical compounds? One of the most common causes of inaccurate melting points is too rapid heating of the melting point compare to the true melting point? Strictly speaking, why is it incorrect to speak of a melting point? What effect would the incomplete drying of a sample (for example, the incomplete removal of a recrystallization solvent) have on the melting point? Why should the melting point sample be finely powdered? You suspect that an unknown is acetanilide (mp 113.5 degree C-114 degree C). Give a qualitative estimation of the melting point when the acetanilide is mixed with 10% by weight of naphthalene. You have an unknown with an observed melting point of 90 degree C-93 degree C. Is your unknown compound A with a reported melting point of 95.5 degree C-96 degree C, or compound B with a reported melting point of 90.5 degree C-91 degree C? Explain. Why is it important to heat the melting point bath or block slowly and steadily when the temperature gets close to the melting point? Why is it important to pack the sample tightly in the melting point capillary? An unknown compound is suspected to be acetanilide (mp 113 5 degree C-114 degree C). What would happen to the melting point if this unknown were mixed with (a) an equal quantity of pure acetanilide? (b) an equal quantity of benzonic acid? Which would be expected to have the higher boiling point t-butyl alcohol (2-methyl-2-proponal) or n-butyl alcohol (1-butanol)? Explain. What is the purpose of the side arm of the thermometer adapter in Figure 3.13?
What effect would poor circulation of the melting point bath liquid have on the observed melting point? What is the effect of an insoluble impurity, such as sodium sulfate, on the observed melting point of a compound? Three test tubes, labeled A, B, and C, contain substances with approximately the same melting points. How could you prove that the tubes contain three different chemical compounds? One of the most common causes of inaccurate melting points is too rapid heating of the melting point compare to the true melting point? Strictly speaking, why is it incorrect to speak of a melting point? What effect would the incomplete drying of a sample (for example, the incomplete removal of a recrystallization solvent) have on the melting point? Why should the melting point sample be finely powdered? You suspect that an unknown is acetanilide (mp 113.5 degree C-114 degree C). Give a qualitative estimation of the melting point when the acetanilide is mixed with 10% by weight of naphthalene. You have an unknown with an observed melting point of 90 degree C-93 degree C. Is your unknown compound A with a reported melting point of 95.5 degree C-96 degree C, or compound B with a reported melting point of 90.5 degree C-91 degree C? Explain. Why is it important to heat the melting point bath or block slowly and steadily when the temperature gets close to the melting point? Why is it important to pack the sample tightly in the melting point capillary? An unknown compound is suspected to be acetanilide (mp 113 5 degree C-114 degree C). What would happen to the melting point if this unknown were mixed with (a) an equal quantity of pure acetanilide? (b) an equal quantity of benzonic acid? Which would be expected to have the higher boiling point t-butyl alcohol (2-methyl-2-proponal) or n-butyl alcohol (1-butanol)? Explain. What is the purpose of the side arm of the thermometer adapter in Figure 3.13?
Elin HesselLv2
15 Sep 2019