Can someone answer these questions for me please?

15. Use bond energies to determine the ∆H for the combustion of methane (CH₄).

16. Use Hess's law to determine the ∆H for the combustion of liquid methanol (CH₃OH).

17. Using your answers from question 16, how much energy will you get from burning 245.0 g of methanol in excess oxygen?

18. The ∆S is 209.6 J/K for the following reaction:
C₂H₄ (g) + 3O₂ (g) → 2CO₂ (g) + 2H₂O (g)

• What is the absolute entropy of O₂ (g)?

19. What is ∆G for the following reaction at 298 K?
2C₆H₆ (l) + 150₂ (g) → 12CO₂ (g) + 6H₂O (g)

20. If a reaction has a ∆H of -120.0 kj/mole and is spontaneous for all temperatures less than 200.0 K, what is ∆S?

answer: enthalpy

explanation:

for a exothermic reaction, the energy is released i.e. the energy of the products is lower than the energy of the reactants.

= enthaply

= energy of products

= energy of reactants

as , thus comes out to be negative. negative value of enthalpy shows that the reaction is exothermic.

i think its 5049.

i hope this !

explanation:

it can be observed without changing the identity of the object.

it depends on what substance you're talking about as well as many other factors. in quantum mechanics, the observation of particles affects the observers ability to measure certain properties. for example: you can know the velocity of a particle, but you can't know it's position; or you can know it's position, but not it's velocity. it's like trying to find out where a grain of sand is by throwing other grains of sand at it. once you find out where it is, it's been moved. it's also like trying to find an answer to the question of whether or not a tree falling in a forest makes a sound if nobody is there to hear it. paradoxically, the only way to find out is to be there and hear it.