Answer:
At the burner temp. and pressure, 18.85 litres of air is needed to completely combust each gram of propane
Explanation:
The combustion stoichiometry is as follows:
C₃H₈ + 5O₂ = 4 H₂O + 3CO₂ The molecular weights (g/mol) are:
MW 44 5x32 4x18 3x44
So each gram of propane is 1/44 = 0.02272 mol propane
and will need 5 x 0.02272 = 0.1136 mol oxygen
At 0.21 mol fraction oxygen in air, 0.1136 / 0.21 = 0.54 mol air is needed to burn the propane.
At the low pressure in the burner we can use the Ideal Gas Law
PV=nRT, or V = nRT/P
P = 1.1 x 101325 Pa = 111457 Pa
T = 195°C + 273 = 468 K
R = 8.314
and we calculated n = number of moles air = 0.54 mol
So V m³ = 0.54 x 8.314 x 468 / 111457 = 0.0188 m³ = 18.85 litres air.
The tilt of the Earth on its axis is what causes the seasons.
The correct answer is: [D]: " milk " .
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Choice [A]: "soil" is incorrect; since "soil" is "heterogeneous" {composed of many different "ingredients" .].
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Same with "Choice [B]: "granola" [composed of many different ingredients—clumps of sweetened oats, raisins, coconuts, etc.].
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Same with "Choice [C]: "salad dressing". {Notice how we usually have to "shake the bottle" ? Composed of multiple ingredients, (e.g. oil, vinegar, and spices, or oil and other spices, and more ingredientes).
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Choice: [D]: "milk", as a liquid, is a single, well-mixed, uniform, mixture; as such, it is "homogeneous". Note: "homo-" means "same".
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