A 13.0-L scuba diving tank contains a helium-oxygen (heliox) mixture made up of 23.6 g of He and 4.85 g of O2 at 298 K. Calculate the mole fraction of each component in the mixture.

For a research project, a student decided to test the effect of the lead(ii) ion (pb2+) on the ability of salmon eggs to hatch. this ion was obtainable from the water‐soluble salt, lead(ii) nitrate, which the student decided to make by the following reaction. pbo(s) + 2 hno3(aq) → pb(no3)2(aq) + h2o losses of product for various reasons were expected, and a yield of 86.0% was expected. in order to have 5.00 g of product at this yield, how many grams of pbo should be reacted? (assume that sufficient nitric acid, hno3, would be used.)

Nitric acid can be formed in two steps from the atmospheric gases nitrogen and oxygen, plus hydrogen prepared by reforming natural gas. in the first step, nitrogen and hydrogen react to form ammonia: (g) (g) (g) in the second step, ammonia and oxygen react to form nitric acid and water: (g) (g) (g) (g) calculate the net change in enthalpy for the formation of one mole of nitric acid from nitrogen, hydrogen and oxygen from these reactions. round your answer to the nearest .

Match the vocabulary terms to their definitions. 1 . a long, chain-like set of molecules made up of repeating units joined end to end polymer 2 . a hard, brittle, heat- and corrosion-resistant material made by subjecting a nonmetallic mineral mixture to intense heat ceramic 3 . a plastic with low elongations that cannot be recycled thermoset 4 . a carbon fiber embedded in a polymer resin matrix thermoplastic 5 . a plastic with high elongations that can be recycled crystal 6 . a solid form resulting from the arrangement of atoms, ions, or molecules in definite geometric patterns composite