An oxide of chromium is made up of 5.20 g chromium and 5.60 g oxygen What is the empirical formula of the oxide?

Uranium is used as a fuel, primarily in the form of uranium(IV) oxide, in nuclear power plants. This question considers some uranium chemistry. (a) A small sample of uranium metal (0.169 g) is heated to between 800 and 900 C in air to give 0.199 g of a dark green oxide, UxOy How many moles of uranium metal were used? What is the empirical formula of the oxide, UxOy? What is the name of the oxide? How many moles of UxOy must have been obtained? (b) The naturally occurring isotopes of uranium are 234U, 235U, and 238U. Knowing that uraniums atomic weight is 238.02 g/mol, which isotope must be the most abundant? (c) If the hydrated compound UO2(NO3)2 z H2O is heated gently, the water of hydration is lost. If you have 0.865 g of the hydrated compound and obtain 0.679 g of UO2(NO3)2 on heating, how many waters of hydration are in each formula unit of the original compound? (The oxide Ux, Oy is obtained if the hydrate is heated to temperatures over 800C in the air.)

The structure of one of the bases in DNA, adenine, is shown here. Which represents the greater mass: 40.0 g of adenine or 3.0 1023 molecules of the compound?

Uranium is used as a fuel, primarily in the form of uranium(IV) oxide, in nuclear power plants. This question considers some uranium chemistry. A small sample of uranium metal (0.169 g) is heated to 900 °C in air to give 0.199 g of a dark green oxide, UxOy. How many moles of uranium metal were used? What is the empirical formula of the oxide UxOy? What is the name of the oxide? How many moles of UxOy, must have been obtained? The oxide UxOy is obtained if UO2NO3 · n H2O is heated to temperatures greater than 800 °C in air. However, if you heat it gently, only the water of hydration is lost. If you have 0.865 g UO2NO3 · n H2O and obtain 0.679 g UO2NO3 on heating, how many molecules of water of hydration were there in each formula unit of the original compound?

A substance X2Z has the composition (by mass) of 40.0% X and 60.0% Z. What is the composition (by mass) of the compound XZ2?

l-Dopa is a drug used for the treatment of Parkinson’s disease. Elemental analysis shows it to be 54.82% carbon, 7.10% nitrogen, 32.46% oxygen, and the remainder hydrogen. Determine l-dopa’s empirical formula. The molar mass of l-dopa is 197.19 g/mol. Determine its molecular formula.

You have a pure sample of apholate, C12H24N9P3, a highly effective commercial insecticide. Calculate the molar mass of apholate. Calculate the mass of N in 100. g apholate. A sample containing 250.0 mg apholate is sprayed on an agricultural field. Calculate the mass of phosphorus in this sample of apholate; express your result in grams. Calculate the number of phosphorus atoms in this sample of apholate.

An Alka-Seltzer tablet contains 324 mg of aspirin (C.9H8O4,), 1904 mg of NaHCO3, and 1000. mg of citric add (H3C6H5O7). (The last two compounds react with each other to provide the "fizz," bubbles of CO2, when the tablet is put into water.) (a) Calculate the amount (moles) of each substance in the tablet. (b) If you take one tablet, how many molecules of aspirin are you consuming?

You have a 20.0-g sample of silver metal. You are given 10.0 g of another metal and told that tills sample contains twice the number of atoms as the sample of silver metal. Is this possible?

A sample of a hydrocarbon (a compound consisting of only carbon and hydrogen) contains 2.59 1023 atoms of hydrogen and is 17.3% hydrogen by mass. If the molar mass of the hydrocarbon is between 55 and 65 g/mol, what amount (moles) of compound is present, and what is the mass of the sample?