Energy changes and rates of reaction

• allanwinters
In summary, the complete combustion of methane produces 802.5 kJ of energy and results in the emission of carbon monoxide (CO) at a rate of 19.14kg/MJ. To find the mass of CO emitted when burning 100g of methane, the total energy produced from the combustion of 100g of methane must be calculated and then used to find the amount of CO emission. However, if the production of CO is significant, this method may not be accurate and a more comprehensive approach is needed.
allanwinters

Homework Statement

The complete combustion of methane is represented in the following equation:
CH4(g) + 2O2 -> CO2(g) +2H2O(g) +802.5 kJ
Assume that natural gas is essentially methane. The emission level of Carbon monoxide, CO(g) from the burning of natural gas is 19.14kg/MJ of energy produced.

Homework Equations

What mass of CO(g) will be emitted when 100g of natural gas is burned?

The Attempt at a Solution

I attempted to convert the 100g of methane into mol (100g/16.04g per mol) and then i multiplied the mol by it's standard molar enthalpy of formation on wikipedia (-74.9KJ/mol) to find the KJ then converted it into MJ and multiplied the methane mol with 19.14Kg/MJ. My answer was wrong. The textbook answer is 95.7 kg.

Don't you also need an equation for the partial burning leading to the formation of CO?

The units seem to be off. 19.14kg/MJ doesn't make sense, as well as producing 95.7 kg of CO when burning 100 g of methane

You're complicating it. 802.5 kJ (I think you've got the sign wrong) is the energy produced from the burning of natural gas. Just calculate the total energy produced for 100 g of methane and use the total energy to find amount of CO emission.

allanwinters
Mastermind01 said:
You're complicating it. 802.5 kJ (I think you've got the sign wrong) is the energy produced from the burning of natural gas. Just calculate the total energy produced for 100 g of methane and use the total energy to find amount of CO emission.
I agree that this can be done instead of my suggestion of using a second reaction, if the production of CO is negligible. But not if it is 19.14kg/MJ

DrClaude said:
I agree that this can be done instead of my suggestion of using a second reaction, if the production of CO is negligible. But not if it is 19.14kg/MJ

Mastermind01 said:
If the production of CO is important, then you can't simply take that combustion of 1 mole of CH4 will release 802.5 kJ. You have to weigh that value with the energy produced by the reaction leading to CO, which releases less energy than the complete combustion.

DrClaude said:
If the production of CO is important, then you can't simply take that combustion of 1 mole of CH4 will release 802.5 kJ. You have to weigh that value with the energy produced by the reaction leading to CO, which releases less energy than the complete combustion.

Aah, I see your point. Thanks

Anyway, my method does get the OP's textbook answer even though it's technically incorrect.

1. What is meant by energy changes in a chemical reaction?

Energy changes in a chemical reaction refer to the amount of energy that is either absorbed or released during the reaction. This can include changes in temperature, light, or other forms of energy.

2. How do energy changes affect the rate of a reaction?

Generally, an increase in energy will lead to an increase in the rate of a reaction. This is because molecules have more energy to overcome activation energy barriers and react with each other.

3. What factors can influence the rate of a reaction?

Several factors can influence the rate of a reaction, including temperature, concentration of reactants, surface area of reactants, and presence of catalysts. These factors can affect the energy of the system and the likelihood of successful collisions between molecules.

4. What is activation energy and how does it relate to energy changes in a reaction?

Activation energy is the minimum amount of energy required for a reaction to occur. In a reaction with a positive energy change, the activation energy represents the amount of energy needed to break bonds in the reactants. In a reaction with a negative energy change, the activation energy represents the amount of energy needed to form new bonds in the products.

5. How are energy changes and rates of reaction related to the concept of equilibrium?

In a reversible reaction, both the forward and reverse reactions have an associated energy change. At equilibrium, the rates of the forward and reverse reactions are equal, meaning that the energy changes are also equal. This allows the system to maintain a constant energy level and remain in equilibrium.

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