How much water needed to power the world through oxidization of hydrogen

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SUMMARY

The discussion focuses on calculating the decrease in ocean water levels required to power the world through the oxidization of hydrogen gas, derived from electrolyzing seawater. The annual energy consumption for transportation is approximately 10^17 kJ, necessitating the production of 4.17x10^15 moles of seawater. Participants emphasize the importance of using seawater's surface area and density to convert moles into volume, rather than relying solely on the ideal gas law (PV=nRT). The key reaction for hydrogen production is 2H2O → 2H2 + O2, with a standard enthalpy change of ΔH=-245.12 kJ/mol.

PREREQUISITES
  • Understanding of stoichiometry in chemical reactions
  • Familiarity with the electrolysis of water
  • Knowledge of seawater density and molar mass
  • Basic principles of thermodynamics, particularly enthalpy changes
NEXT STEPS
  • Research the surface area of Earth's oceans and its impact on water volume calculations
  • Learn about the electrolysis process and its efficiency in hydrogen production
  • Explore thermodynamic principles related to energy conversion and enthalpy
  • Investigate methods for calculating volume from moles using density
USEFUL FOR

Students in chemistry and environmental science, energy researchers, and professionals interested in sustainable energy solutions through hydrogen fuel.

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Homework Statement


The annual world use of liquid hydrocarbon fuels for transportation purposes currently generates about 10^17 kJ. If we could instead run our transportation system by oxidizing hydrogen gas to gaseous water, we would likely have to obtain the hydrogen by electrolyzing water. Suppose we made and stored enough hydrogen for one year by electrolyzing seawater. By how much would the level of the oceans decrease (in m)?
ΔH=-245.12KJ/mol

Homework Equations


pv=nrt
stoichiometry
electrolyzing water: 2H2O --> 2H2 + O2

The Attempt at a Solution



I have gotten to the point where i have calculated I need 4.17x1015 mol of seawater. I am unsure of how to now calculate the decrease in ocean water.
 
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You might want to search for seawater surface area, that is 71% of the surface area of earth. Consider the Earth spherical with some radius. Convert moles into volume of water and viola, you get your answer.
 
turns out i needed to calculate the volume of seawater by using the molar mass and the density rather than through pv=nrt
 

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