Anonymous
Anonymous asked in Science & MathematicsEngineering · 9 months ago

How to find quality?

If a mixture has a volume of 1,276 cubic cm and a mass of 100 grams and the vapor portion has a specific volume of 0.16 cubic meters per kg and the liquid portion has a specific volume of 0.0007 cubic meters per kg.

What is the quality of the mixture?

Using (v-vg)/(vg-vf) i keep getting -0.96. the correct answer is 0.07571, but I don't know ho to get to that.

1 Answer

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  • Anonymous
    9 months ago
    Favourite answer

    You can do a rigorous mass balance (volume of vapor * density of vapor + volume of liquid * density of liquid = 100 g) but the volume of liquid can likely be neglected.

    1276 cm^3 = 0.001276 m^3

    0.001276 m^3 / (0.16 m^3/kg) = 0.007975 kg = 7.975 g

    Quality = 7.975 g / 100 g = 0.0798

    We can clean this up a bit with another iteration since the liquid volume would be the difference.

    Mass of liquid = 100 g - 7.975 g = 92.83 g. Volume of liquid = 64.9 cm^3. That leaves 1276 cm^3 - 64.9 cm^3 = 1211 cm^3 with a mass of 7.56 g of vapor.

    7.56 g / 100 g = 0.0756, much closer to your number.

    Post your work and I can take a look at it.

    < What is the quality of the mixture? >

    Remember that the quality of a mixture is just the mass of vapor / total mass.

    0% is no vapor. 100% is all vapor, no liquid.

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