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Member Posts: 1
When 25 gallons of water are heated from 40 degrees F to 200 degrees F, the volume of this water increases to 26 gallons. If the weight of water at 40 degrees F is 8.33 lbs per gallon, then the weight of water at 200 degrees F is MOST NEARLY
A 8.42 B. 8.23 C. 8.02 D. 7.33
C is the answer, but how do you arrive at this choice??
Thank you for your time and help
Gene
A 8.42 B. 8.23 C. 8.02 D. 7.33
C is the answer, but how do you arrive at this choice??
Thank you for your time and help
Gene
0
Comments

It's all about
knowing the density and doing the math.
http://mathforum.org/library/drmath/view/56355.html8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour
Two btu per sq ft for degree difference for a slab0 
Here You Go!
The density of water can be found by the following:
Density = 62.56 + (0.0003413 x Water Temp)  (0.00006255 x Water Temp x Water Temp)
So, for your 200 degree F water, we get:
Density = 62.56 + (0.00003413 x 200)  (0.00006255 x 200 x 200)
Density = 62.56 + 0.06826  2.502
Density = 60.12626 pounds/cubic foot
Since there are 7.5 gallons of water per cubic foot, the weight of one gallon of 200 degree water is found by:
60.12626/7.5 = 8.016, which is rounded to 8.02
Hope this helps!
P.S. It's on page 730 of:
http://www.heatinghelp.com/products/HeatPumpsACBooks/29/106/ResidentialConstructionAcademyHVACSecondEditionbrbyEugeneSilbersteinThere was an error rendering this rich post.
0 
I would have
divided 25 gal. (the volume at 40*) by 26 gal. (the volume at 200*) and multiplied that ratio by 8.33 lbs./gal to give approx. 8.01 lbs./gal. which is closest to answer C.All Steamed Up, Inc.
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