Assume the plastic bags are made from polyethylene (PE), which is made from ethylene derived from natural gas (assume 100% CH₄), and that one bag weighs 2 grams. Assume that I use 0.5 L of water at 40C to wash each bag. The water is heated from 15C to 40C using natural gas burned at 80% efficiency. The heating value of natural gas is 20,000 BTU/lb. Ignore for now the energy required to drive the polyethylene reactions.

A. How many grams of methane are needed to make a 2-g PE plastic bag?

Assume 2CH₄ + O₂ --> C₂H₄ (ethylene) + H₂O --> (CH₂)_n (polyethylene)

B. How many grams of methane are needed to heat 0.5 L of water from 15C to 40C?