Dadas las siguientes ecuaciones y valores de ∆H° determine el calor de reacción (kJ) a 298 K para la reacción: 3 Fe2O3 (s) → 2 Fe3O4 (s) + 1/2 O2 (g)
Si:
2 Fe (s) + 3/2 O2 (g) → Fe2O3 (s) ∆H°= -823,41 kJ
3 Fe (s) + 2 O2 (g) → Fe3O4 (s) ∆H°= -1120,48 kJ

A3.37-mg sample of protein was chemically digested to convert its nitrogen into ammonia and then diluted to 100.0 ml. then 10.0 ml of this solution was placed in a 50-ml volumetric flask and treated with 5 ml of phenol solution plus 2 ml of sodium hypochlorite solution. the sample was diluted to 50.0 ml, and the absorbance at 625 nm was measured in a 1.00-cm cuvette and found to be 0.486. for reference, a standard solution was prepared from 10.0 mg of nh4cl (molar mass = 53.49 grams/mole) dissolved in 1.00 l of water. then 10.0 ml of this standard was placed in a 50-ml volumetric flask, treated in the same manner as the unknown, and the absorbance found to be 0.323. finally, a reagent blank was prepared using distilled water in place of unknown, it was treated in the same manner as the unknown, and the absorbance found to be 0.076. calculate the weight percent of nitrogen in the protein.

In a chemical reaction at equilibrium, the rate of the forward reaction the rate of the reverse reaction. if the rate of the forward reaction more products are formed.

Phosphorous can form an ion called phosphide, which has the formula p3−. this ion can form an ion called phosphide, which has the formula p3−. this ion properties very similar to those of pforms when a phosphorus atom loses three protonsis called a cationcontains 18 electrons