1) Chromium(III) nitrate is classified as acidic because it is derived from a weak base (chromium(III) hydroxide Cr(OH)₃) and a strong acid (nitric acid HNO₃). 2) Sodium hydrosulfide is considered basic because it results from a strong base (sodium hydroxide NaOH) and a weak acid (hydrogen sulfide H₂S). 3) Zinc acetate is slightly basic since zinc hydroxide (Zn(OH)₂) is a stronger base than acetic acid (CH₃COOH).
To calculate the moles of MgSO4.7H2O, we find the molar mass equals 246, thus moles = 32 / 246 = 0.13 moles. Upon heating, all 7 H2O from one molecule will evaporate. The total moles of H2O present amount to 7 x 0.13 = 0.91, and the mass of that H2O is 0.91 x 18 = 16.38g. Therefore, the mass of the anhydrous MgSO4 that remains is 32 - 16.38 = 15.62 g.
While the original inquiry is incomplete, the comprehensive question is:
Many chemicals can illustrate spots on a TLC plate that have been processed and dried. The permanganate used in the video creates yellow spots against a purplish background, taking advantage of the oxidizing capability of basic permanganate (MnO4), which outperforms chromic acid as an oxidizing agent. Chromic acid can also be employed to visualize spots, resulting in a green hue on the yellow background, indicating oxidation. So, can chromic acid be conveniently used to visualize spots when tracking a reaction converting an alcohol into a ketone? What observations are anticipated if one attempts this? Furthermore, if a small amount of alcohol is included in a solvent mixture for eluting your TLC plate, why must the plate be fully dried before visualizing the spots with an oxidizing agent like permanganate or chromic acid?
Answer:
Typically, using chromic acid to visualize spots during the conversion of alcohol to ketone is not feasible. The alcohol (substrate) will convert into its respective ketone due to the presence of chromic acid, causing the spots for the product and the reactant to align horizontally. This alignment complicates differentiation between the spots, making chromic acid unsuitable for this purpose.
It's vital to ensure that the plate is completely dry before observing spots with an oxidizing agent, even if alcohol is present in the solvent mixture. Incomplete drying could lead to oxidation of the alcohol by the oxidizing agent, resulting in transformation to carboxylic acid or ketone, thereby creating a new spot.
