Assume that due to dwindling supplies of crude oil and natural gas, the US embarks on a plan to implement the "hydrogen economy"

Could you please explain what formula and step are involved and please provide (example) problem if possible Assume that due to dwindling supplies of crude oil and natural gas, the US embarks on a plan to implement the "hydrogen economy" for which hydrogen will be generated by electrolysis of water. The source of electricity is from photovoltaic (PV) conversion of sunlight in the southwestern US. (a) Assume that a flat plate PV system is used, with a solar conversion efficiency of 25 percent and a hydrogen production efficiency of 95 percent. Assume the average annual insolation in the southwest is 270 watts per square meter. Calculate the annual electrical energy produced in kJ/sq. m... click for more

Chemical Reaction - Find unknown mass

A stoppered flask at 25 C contains 250 mL water, 200 mL octanol, and 50 mL of air. An unknown mass of o-xylene is added to the flask and allowed to partition among the phases. After equilibrium has been established, 5.0 mg of o-xylene are measured in the water. What is the total mass (g) of o-xylene present in the flask?

The half-life of tritium is approximately 12 years.

I have been stuck on this problem for ever! I am not good with ratios and I have no idea what equation I need to solve this problem. Please help, thank you. The half-life of tritium is approximately 12 years. What will be the molar ratio of tritium to helium-3 in a sealed sample after 25 years?

Resulting pH

I am trying to figure this out but I don't have an measurement for water. Does that matter? Also, can I use the henderson hasselbalch equation to solve this? I need help with the setup of this problem. Thank you. In manufacturing a fruit drink, citric acid is added to water in the amount of 0.1 mol/L. What is the pH of the resulting solution?

Mass of o-xylene

Im confused on how to set this problem up while incorporating the water, octanol, and air in one equation so I can solve for the mass. Help is much appreciated! thank you A stoppered flask at 25 C contains 250 mL water, 200 mL octanol, and 50 mL of air. An unknown mass of o-xylene is added to the flask and allowed to partition among the phases. After equilibrium has been established, 5.0 mg of o-xylene are measured in the water. What is the total mass (g) of o-xylene present in the flask?