Question

Suppose a boil water notice is sent out advising all residents in the area to boil their water before drinking it or using it for cooking. You need to boil 12.5 L of water using your natural gas (primarily methane) stove. What volume of natural gas is needed to boil the water if only 14.6% of the heat generated goes towards heating the water. Assume the density of methane is 0.668 g/L, the density of water is 1.00 g/mL, and that the water has an initial temperature of 24.8 °C. Enthalpy of formation values can be found in this table. Assume that gaseous water is formed in the combustion of methane. volume of methane:

Answer 1

Answer! Given that, Volleme of water = 12.5L=12500ml mafs of water = ( volume of water) x (density of water) = 12 500mL)x (1000 g/ml) = 12500g Heat required to boil water = (mats of water)x(specific heat wates)(final temp-Initial temp) = (1 2500 g)x (4.1845/99) x(100C-24.8%) 3 3932960 J § 3932.9KT Heat jien by combustion = Cheat required) Crescent of heat to boilwater)) taken by boiling) - (3932.9kJ)/(14.6%) = (3932.9K5) 160-166) We know, = 26937.692 kJ enthalpy of combustion of methane - 802.5kJ/mol. moles of methane used - CHeat given by combustion) /centhalpy of combustion opp methane) = 126937670 X5X(802.5K3/m01) = 33.5 mol

mass methane -(moles methane used)x(moleks mass methane) = (33,5 mol) x (16.049/mol). = 537.369 NOW, volume of methane = (mcess methane) / (density of methane) = 637.348)/(0.6683/4) = 804141. therefore, volume of methane = 1804042 - X -