Determine number of moles of air.

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In summary, the conversation discusses the process of heating air in a house using natural gas (CH4). The necessary information to solve the problem includes the floor area and ceiling height of the house, specific heat capacity of air and methane, and the molar mass and density of air. The first step is to determine the number of moles of air, which can be found using the given density and molar mass. Then, the heat energy given off by the combustion of methane must be calculated. However, there is a missing piece of information regarding the temperature change in methane. Overall, the conversation highlights the need for more information to accurately solve the problem.
  • #1
hola
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Suppose you want to heat the air in your house with natural gas (CH_4). Assume your house has 275 m^2 of floor are and ceilings are 2.5 m from floors. The air in your house has a specific heat capacity of 29.1 J/mol K. The number of moles in the house can be found by assuming the molar mass of air is 28.9 g/mol and that the density of the air at these temperatures is about 1.22 g/L. How much grams methane do you have to burn to heat air from 15.0 to 22.0 C?

So, here is how I think I can solve it.
1. Determine number of moles of air. I have no idea how to do that.
2. specific heat*temp*moles of CH4 = specific heat*temp*moles of water.

But I can't! Any help, please?
 
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  • #2
For (1) you have been given all the information except volume conversion
1 cubic meter = 1000L
 
  • #3
Okay:
For air, I got:
Change in temp: 7.0 C
specific heat: 29.1 J/molK
mass= 839*10^5 g (should I convert this into moles?)
For methane:
specific heat: 4.18 j/molK
I need to solve for mass, right?
But I don't have temperature change in methane?

HELP! please,:smile: ?
 
  • #4
Well for one... how do you heat a house with methane without combustion?

You're missing a piece of information
 
  • #5
2. specific heat*temp*moles of CH4 = specific heat*temp*moles of water.

why water?

First, how would you find the heat energy given off by the combustion of methane?
 

1. What is the definition of a mole in chemistry?

A mole is a unit of measurement in chemistry that represents the amount of a substance. It is defined as the amount of a substance that contains the same number of particles (atoms, molecules, or ions) as there are atoms in exactly 12 grams of carbon-12.

2. How do you determine the number of moles of air?

To determine the number of moles of air, you would need to know the volume of air (in liters) and the pressure and temperature at which the measurement was taken. Then, you can use the ideal gas law, PV = nRT, where P is pressure, V is volume, n is the number of moles, R is the gas constant, and T is the temperature in Kelvin, to solve for n.

3. What is the average molar mass of air?

The average molar mass of air is approximately 28.97 grams per mole. This value can vary slightly depending on the composition of the air, as it is primarily made up of nitrogen (78%) and oxygen (21%), with small amounts of other gases such as carbon dioxide and argon.

4. Why is it important to determine the number of moles of air?

Determining the number of moles of air is important in many applications, such as in chemical reactions or in understanding the behavior of gases. It can also be used in environmental studies to measure the amount of pollutants in the air.

5. Can the number of moles of air change?

Yes, the number of moles of air can change depending on the conditions. If the volume, pressure, or temperature of the air changes, the number of moles will also change accordingly. Additionally, the composition of the air can also affect the number of moles, as different gases have different molar masses.

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