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A runner weighs 687 N and 71% of this weight is water. (a) H

  • Thread starter Alice7979
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Homework Statement


A runner weighs 687 N and 71% of this weight is water. (a) How many moles of water are in the runner's body? (b) How many water molecules (H2O) are there?

Homework Equations


n = N/NA
n= m/mass per mole
NA = 6.022E23
F=ma
H: 2*1
O: 16

The Attempt at a Solution


a)
687/9.8=70.1 g
70.1 * .71 = 49.77 g of h20
49.77/18 u = 2.765

b) 6.022E23 * 2.765 = 1.665



 

Answers and Replies

  • #2
haruspex
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  • #3
Nathanael
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The Attempt at a Solution


a)
687/9.8=70.1 g
70.1 * .71 = 49.77 g of h20
49.77/18 u = 2.765
Is this reasonable? A man who weighs 70.1 grams? Must be a world record...

(Posted at the same time as haruspex, oops)
 
Last edited:
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I forgot the formula was in kg
 
  • #5
haruspex
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I forgot the formula was in kg
So does that change your answer?
 
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So does that change your answer?
Yes it did, thanks
 
  • #7
haruspex
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(Posted at the same time as haruspex, oops)
Always happy to have corroboration.
 

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