A) CH4 + 2O2 "yields" CO2 +2H2O
For the above reaction the change in enthalpy is -890KJ. If 10g of CH4 is reacted with 64g of O2, how mch heat will be generated?
Please show me how it's done and not just te answer. Thank you in advance.
For the above reaction the change in enthalpy is -890KJ. If 10g of CH4 is reacted with 64g of O2, how mch heat will be generated?
Please show me how it's done and not just te answer. Thank you in advance.
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Notice that these are all gases. Even the water product is assumed to be steam, a gas. Then you are given masses so you can calculate the number of moles of each gas. Now the question here is whether the change in enthalpy is per mole of methane (CH4) or gram of methane. Should we assume that the change in enthalpy is 890,000 J/mol. A mole of CH4 has a mass of:
12.01 + 4*(1.01) = 12.01 + 4.04 = 16.05 g That's over 5 kJ/g so you should check to make sure that it is not 890 kJ/kmol.
But, since methane is a fuel then 890 kJ/mol would be right. The negative sign is just the way your book or teacher decided to say that it gives off heat when burnt. The exact opposite is true when you say that it takes 890 kJ/mol to make CH4.
The number of grams of CH4 present is 10/16=5/8. Your eq. shows that you need 2 mol O2/mol CH4 so you would need 10/8 mol O2 or 1.25 moles. A mole of O2 has a mass of 32 g so you have excess O2.
The total energy produced is 890kJ * (5/8)
12.01 + 4*(1.01) = 12.01 + 4.04 = 16.05 g That's over 5 kJ/g so you should check to make sure that it is not 890 kJ/kmol.
But, since methane is a fuel then 890 kJ/mol would be right. The negative sign is just the way your book or teacher decided to say that it gives off heat when burnt. The exact opposite is true when you say that it takes 890 kJ/mol to make CH4.
The number of grams of CH4 present is 10/16=5/8. Your eq. shows that you need 2 mol O2/mol CH4 so you would need 10/8 mol O2 or 1.25 moles. A mole of O2 has a mass of 32 g so you have excess O2.
The total energy produced is 890kJ * (5/8)
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find mass of CH4 and O2 then
find num of moles of co2 formed by 10g of CH4 and 64g of O2 then multiply that num of moles with -890 kj you will get amount of energy generated
find num of moles of co2 formed by 10g of CH4 and 64g of O2 then multiply that num of moles with -890 kj you will get amount of energy generated