4. a) A portable electronic device delivers 2.5W by having five fuel cells in series each delivering 1A at 0.5V. If you want it to have an operating lifetime of 100h, assuming 100% fuel utilization, what is the minimum amount of hydrogen fuel (in grams) required? b) If this H2 fuel is stored as a compressed gas at 500atm, what volume (cm3) would it occupy? Assume it is an ideal gas at room temperature (298K).R=0.08205Latm/molK. If instead it is stored as a metal hydride at 5wt% hydrogen, what volume would it occupy? The metal hydride has a density of 10g/cm3. c) Repeat part a) if methanol (CH3OH) is the fuel, that is find the minimum amount of methanol 2 (in grams) required for the stack. What would be the corresponding volume of methanol fuel? Density of liquid methanol =0.79g/cm3. Hint: For fuel cells in series, add volts/cell for stack voltage. All cells carry the same current. Ideal gas law: PV=nRT