Heats of formation calculation:

Tables are available for heats of formation of common compounds and ions in aqueous solution in most general chemistry textbooks. Calculate DH for the following reaction: 8 Al(s) + 3 Fe3O4(s) --> 4 Al2O3(s) + 9 Fe(s)

chem problems

. The Zinc in a 1.200g sample of foot powder was precipitated as ZnNH4PO4. The strong heating of the precipitate yielded 0.4089g of Zn2P2O7. Calculate the mass percent of zinc in the sample of foot powder. 2. A mixture contains only sodium chloride and potassium chloride. A 0.1586g sample mixture was dissolved in water. It to ...continues

Chem problem

An electric furnace produces phosphorus by the following reaction: Ca3(PO4)2(s) + C(s)+SiO2(s)= CaSiO3(s)+CO(g)+P(I) An initial reaction mixture contains 1500g calcium phosphate, 250 g carbon and 1000g silicon dioxide. a) What is the limiting reactant? b) What is the theoretical yield of phosphorus? c) After the reaction ...continues

thermochemistry

I need to explain qualitatively the relationship between hydration enthalpy and ion radius (for group 1 cations compared to group 7 anions). I also need to explain the relationship between lattice energy and ion radius of sodium salts compared to cloride salts. I was also wondering why the molar heat of solution depends on the f ...continues

Converting units

Hi. I do not understand the process for converting...can you please explain step by step? Use the appropriate symbol (>,<, or =) 303 m ______303X10^3km 1.50 cm^3_______1.50X10^3nm^3 Thank you.

Conversion Factors

Having a problem really understanding Conversion Factors. Where do I get the conversion factor? Can you give me a step by step how to solve? 2-credits for a very thorough answer! Problem, Use conversion factors to convert 4.2yds to Meters,Centimeters,Micrometers and Kilometers. Thank you.

Density

A cylindrical bar of gold that is 1.5 in. high and 0.25 in. in diameter has a mass of 23.1987g, as determined on an analytical balance. An empty graduated cylinder is weighed on a triple beam balance and has a mass of 73.7g. After pouring a small amount of liquid into the graduated cylinder, the mass is 79.16g. When the gold cyl ...continues

Mass

The density of earth is about 3.5g/cm^3. If the earth has a radius of 7000 miles, what is its mass? Step by Step

How long animacules in meters?

Anton Von L. a 17th century pioneer in the use of the microscope, described the microrganisms he saw as "animalcules" whose length was "25 thousandths of an inch." How long were the animalcules in meters.

Density of Oil

If a serving of oil is exactly 1 tablespoon, which has a mass of 14g, and there are 96 servings in the container, what is the density of the oil in grams per milliliter (g/ml)?