During backcountry hiking, your prof set up camp near the Mount Rainier summit w

Question

During backcountry hiking, your prof set up camp near the Mount Rainier summit where the atmospheric pressure is 60 kPa, and he wanted to make a hot meal by boiling water and rehydrating food. The water was boiled using a stove attached to an 8 oz. (236mL) fuel canister. The fuel canister initially contained only 50 mL pressurized liquid fuel. These fuel canisters are dangerous because if they are heated the liquid contained inside can expand into gas, which would rupture the canister walls and potentially cause an explosion. The canister walls can withstand pressures of up to 25 bar gauge. Using the physical properties of the fuel shown in the table below, address the following questions: What is the boiling point of water at this elevation? What fuel temperature would cause the canister to burst? To find the percentage of fuel that is in the vapor phase at the bursting pressure, which equation of state should we apply and why? Before heating, how many moles of liquid fuel are in the tank? At the temp and pressure at which the canister bursts, what is the molar volume of the fuel vapor? What is the fraction of fuel in the vapor phase at the bursting pressure?

Explanation / Answer

a) Bpt = Tb = 272 k

b) V1/T1= V2/T2

    50/272 = 236/T2

So T2= 236*272/50 = 1283 k

c) P1V1 =P2V2

Here P1 = 60 k Pa

P2 = 25*100 kPascals

calculate V2 and then percentage from this value

d) vol = 50 ml

specific gravity = 0.604

weight = vol * specific gravity = 50*0.604 = 30.2 grams

e) Tc = 425 k

P = 25*100 2500 kPascals

f)

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