(multiple choice!!)
A balloon filled with helium gas at 15.0oC occupies 1.5 L at 760 mmHg. The balloon is immersed in liquid nitrogen at 77 K, changing the volume to 3.00 L. What is the new pressure of the balloon in mmHg?

0.039 mmHg

1950 mmHg

101.6 mmHg

0.0098 mmHg

101.6 mmHg

Explanation:

number of molecules / avogadro's number * molecule molecular = mass

explanation:

we define a gram-molecular weight as the mass of one mole of any element or compound. a mole contains avogadro's number of units (molecules) –  

6.022

x

10

23

. so, dividing the number of molecules by avogadro's number gives us the number of moles. multiplying that by the molecular weight gives us the mass. from the periodic table we find the gram-molecular weight of u to be238 and of f to be19. so,  

u

f

6

will have a gram-molecular weight of 352g.

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