Question 4 Pure caffeine has a literature melting point of 238C. If you performed a series of extractions on an aqueous tea brew with the intention of isolating the caffeine, and recorded the melting point of your isolated solid as 231-236 C, which of the following statements are TRUE? Select all that apply. no conclusion can be made about the identity of the solid from the data given The product mp range is broad, which indicates impure caffeine has likely been isolated The solid mp is lower than the literature mp for caffeine, which indicates impure caffeine has likely been isolated The solid cannot be caffeine Question 5 In a TLC analysis, which of the following statements is TRUE? Select all that apply. A given compound will have the same Rf value regardless of what solvent (eluent) is used Rf values can range from-1 to +1 TLC can help determine how many components are in a mixture TLC can help assess purity of a compound isolated from a reaction Question 6 Which of the following may cause errors in thin-layer chromatography? Select all that apply. Picking up the TLC chamber (beaker) and walking around with it while the TLC analysis is being conducted 4 pts Putting eluent in the TLC chamber at a level ABOVE the origin line drawn on the TLC plate Spotting too much of the compound at the origin 4 pts 4 pts