Not understanding how to determine Stoichiometric air to fuel ratio

In summary, the question is asking for the stoichiometric air to fuel ratio for complete combustion of a fuel with 86% carbon and 14% hydrogen by mass. The solution involves using the mass percentage composition to determine the molar amounts of carbon and hydrogen in a 100g basis, assuming all of the carbon becomes carbon dioxide and all of the hydrogen becomes water. From there, an equation can be created to calculate the amount of oxygen consumed.
  • #1
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Homework Statement


Hey, just doing a few problems and i have found i have no understanding of how to solve these types of question, if anyone can help or provide info it would be great thanks...

Q " The fuel oil supplied to a boiler contains 86% carbon and 14% hydrogen by mass. Determine the stoichiometric air to fuel ratio for complete combustion of the fuel."


Homework Equations



Composition of air by mass : Oxygen 23% Nitrogen 77%

Relative Atomic Mass Oxygen (O) 16 , Carbon (C) 12 Hydrogen (H) 1

The Attempt at a Solution

 
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  • #2
Consider a basis of 100g of the fuel. Based on the mass percentage composition of the fuel, you should be able to work out how many moles of carbon and hydrogen in this 100g basis.

You should be able to assume that all of the carbon becomes carbon dioxide and all of the hydrogen becomes water. Based on the molar amounts of carbon and hydrogen, you can work out how much water and carbon dioxide will form and thus the amount of oxygen consumed.

Can you work from there?
 
  • #3
So basically create an equation and then sub in the molar amounts??
 

Related to Not understanding how to determine Stoichiometric air to fuel ratio

1. What is Stoichiometric air to fuel ratio?

Stoichiometric air to fuel ratio is the ideal ratio of air to fuel required for complete combustion. It is the point at which all the fuel is burned and there is no excess oxygen or unburned fuel left over.

2. How is Stoichiometric air to fuel ratio calculated?

The Stoichiometric air to fuel ratio is calculated by dividing the mass of air required for complete combustion by the mass of fuel. This ratio is different for different fuels and can be found using the chemical formula of the fuel.

3. Why is Stoichiometric air to fuel ratio important?

Stoichiometric air to fuel ratio is important because it ensures efficient and complete combustion of fuel, which leads to maximum energy output and minimal emissions.

4. How does the Stoichiometric air to fuel ratio affect engine performance?

The Stoichiometric air to fuel ratio affects engine performance by determining the amount of power and torque that can be produced. An incorrect ratio can lead to decreased performance, increased fuel consumption, and potential damage to the engine.

5. What factors can affect the Stoichiometric air to fuel ratio?

The Stoichiometric air to fuel ratio can be affected by factors such as altitude, temperature, and fuel composition. Changes in these factors can alter the amount of air and fuel needed for optimal combustion, resulting in a different ratio.

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