Consider the following reaction: 2CH3OH(g)2CH4(g)+O2(g),H=+252.8 kJ Part A:Calcu

Question

Consider the following reaction: 2CH3OH(g)2CH4(g)+O2(g),H=+252.8 kJ Part A:Calculate the amount of heat transferred when 29.0 g of CH3OH(g) is decomposed by this reaction at constant pressure. Express the heat to three significant digits with the appropriate units. part B: For a given sample of CH3OH, the enthalpy change during the reaction is 82.3 kJ . What mass of methane gas is produced? Express the mass to three significant digits with the appropriate units Part C :How many kilojoules of heat are released when 38.5 g of CH4(g) reacts completely with O2(g) to form CH3OH(g) at constant pressure? Express heat to three significant digits with the appropriate units.

Explanation / Answer

The reaction is endothermic as suggested by H=+252.8 kJ

2CH3OH(g)2CH4(g)+O2(g),H=+252.8 kJ

The reaction suggests 2 moles of CH3OH reacts leading to transfer 252.8Kj of energy

Moles =mass/molar mass = 29/32 =0.91 moles

0.91 moles of CH3OH gives 0.91*252.8/2= 115 Kj of energy is transferred.

Molar mass of CH4= 16 g/mol

252.8 Kj of energy is absorbed by 2 moles of CH4= 2*16= 32 gm of methane

82.3 Kj of energy is absorbed by 82.3*32/252.8 =10.42 gm of methane

2CH4(g)+O2(g) ------à2CH3OH(g),H=-252.8 kJ ( the reverse reaction is exothermic).

32 gm of methane completely reacts to produce 252.8 Kj of energy

38.5 gm of methane reacts to produce 252.8*38.5/32 Kj of energy =304.2 KJ of energy.

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