State Hess' law of constant heat summation. (b) Calculate the enthalpy of formation of CH4 from the following data:
i) C(s) + O2(g) → CO2(g); ∆H = -393.7 kJ/mol
ii) H2(g) + 1⁄2 O2(g) → H2O(l); ∆H = -285.8 kJ/mol
iii) CH4(g) + 2 O2(g)→ CO2(g) + 2H2O(l); ∆H = -890.4 kJ/mol

What happens to energy in an open system?

If the root word engage means “to connect with something,” what does the word disengage mean in the following sentence? he disengaged the gears by stepping on the clutch pedal.a.added more engine powerb.activated a connection to the pedalc.stalled the engined.released a connection to the pedal

From the options provided for each element below, choose the properties that it may have based on its location in the periodic table fluorine (f): highly reactive nonmetal shiny a conductor