A sample of hydrogen sulfide, H2S, has a mass of 57.25 g. Calculate the number of hydrogen sulfide molecules in the sample.

Crime scene investigators keep a wide variety of compounds on hand to help with identifying unknown substances they find in the course of their duties. One such investigator, while reorganizing their shelves, has mixed up several small vials and is unsure about the identity of a certain powder. Elemental analysis of the compound reveals that it is 67.31 % carbon, 6.978% hydrogen, 4.617% nitrogen, and 21.10% oxygen by mass.     Which of the compounds could the powder be? C17H19NO3C17H19NO3 = morphine, analgesic C17H21NO4C17H21NO4 = cocaine, illicit drug C7H5N3O6C7H5N3O6 = 2,4,6-trinitrotoluene (TNT), commonly used explosive C10H15NC10H15N = methamphetamine, stimulant C4H5N2OC4H5N2O = caffeine, stimulant C11H15NO2C11H15NO2 = 3,4-methylenedioxymethamphetamine (MDMA), illicit drug C21H23NO5C21H23NO5 = heroin, illicit drug C3H6NO3C3H6NO3 = hexamethylene triperoxide diamine (HMTD), commonly used explosive

Part A. What is the mass of 9.50 moles of magnesium chloride, MgCl2? Express your answer with appropriate units. Part B. How many moles of nitrogen, N, are in 76.0g of nitrous oxide, N2O? Express your answer with the appropriate units.

Chlorophyll molecules are responsible for the green pigmentation of plants. Differing chemically isolated molecular chlorophyll compounds are named as "Chlorophyll X" (where "X" is a variable denoting the actual molecular fragments which are represented by the labels R2, R3, R7, Rg, R17). Suppose one molecule of ChlorophyllX contains 5 oxygen atoms, and Chlorophyll X is 13.14 % oxygen by weight. Using only this information and the atomic mass of oxygen, determine the molecular mass of Chlorophyll X. The Chlorophyll X molecule contains one magnesium atom. What mass of magnesium is found in 7.11 g of Chlorophyll X compound?