Methane (CH4) is a common fuel to heat homes in the winter. What is the molar enthalpy of combustion of methane? Assume this combustion occurs entirely in the gas phase. Bond Enthalpies(in kJ mol−1):C−C: 347 C−H: 413 H−H:432 O−H: 467 C=C: 614C=O: 745O=O: 498 A)−710kJ mol−1
B)−297 kJmol−1
C)−1843 kJmol−
1D)+792 kJmol−1
E)+567 kJmol

first let us lay out the formula for potential

and kinetic energy:

pe = mgh

ke = (mv^2)/2

where: m=mass, v=velocity, g=gravitational

acceleration, h=height

calculating for mass using the known values of

pe:

340j = m (9.81 m/s^2) (50ft) (1m/3.28ft)

m = 2.27 kg

the law of conservation of energy states that

energy is neither created nor destroyed. therefore, the change in kinetic

energy from 50 ft to 35 ft would be equal to the change in potential energy

from 50 ft to 35 ft. however it would be opposite in signs since one is losing

while other is gaining.

ke(35ft) – ke(50ft) = - [ pe(35ft) – pe(50ft]

ke(50ft) = 0 since the brick is initially at rest

ke(35ft) = 340j - 2.27kg (9.81 m/s^2) (35ft)

(1m/3.28 ft)

ke(35ft)

= 102.38 j

answer; talc and gypsum;

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.

the answer is c i took the test