Consider the following reaction: 2CH3OH(g) → 2 CH4(g) + O2(g) H=+252.8 kJ

2. Consider the following reaction: 2CH3OH(g) → 2 CH4(g) + O2(g) H=+252.8 kJ 

a. this reaction is endothermic because the sign of enthalpy given is positive

b. Calculate the amount of heat transferred when 24.0 g of CH3OH(g) is decomposed by this reaction at constant pressure. 

moles of CH3OH= 24.0g/32.04 g/mol=0.749moles

2moles of CH3OH absorbs +252.8kJ

=0.749moles x (+252.8kJ/2moles)=94.7kJ

c. For a given sample of CH3OH, the enthalpy change during the reaction is 82.1 kJ. How many grams of methane, CH4, are produced? 

2 moles of CH3OH absorbs +252.8kJ

=82.1kJ x (2moles/+252.8kJ)=0.6495moles

molar mass of CH3OH= 32.04g/mol

mass=0.6495moles x 0.6495moles=20.8g

d. 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? 

moles of CH3OH=38.5g/32.04g/mol=1.2016moles

2 moles of CH3OH absorbs +252.8kJ

thus

=1.2016moles x (252.8kJ/2moles)=151.9kJ

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