HELP WITH: Boyle’s Law, Charles’ Law, and Gay-Lussac’s Law?

Question

I don't know how to solve this question and I'm unsure which law it is.

A diver has about 0.05L of gas dissolved in his blood while swimming 200 feet underwater (at apressure of 7.05atm). He returns too quickly to the surface, quickly reaching a depth of 20 feet (ata pressure of 1.60atm). What is the new volume within his blood?

and i want to see if this one is correct

A submarine containing 15,000L of air at an air pressure of 1.2atm breaks apart deep within the

ocean, where pressures reach 250atm. What volume of air would escape out of the submarine at

that depth?

Answer 1

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A diver has about 0.05L of gas dissolved in his blood while swimming 200 feet underwater (at apressure of 7.05atm). He returns too quickly to the surface, quickly reaching a depth of 20 feet (ata pressure of 1.60atm). What is the new volume within his blood?

  ....   There is no mention of temp. in the problem, so the only logical thing to do is assume constant temp .. good assumption because body temp. stays nearly constant 37C.  So this would obviously not be any law that deals with temp changes.  Also ...  do any gas laws really apply?  We have a gas dissolved in a liquid.  this 0.05L is not really still a gas. ==  This seems to be a question of little real value, except maybe to create some interest in the student.

     PV  =  PV

     7.05 X 0.05 = 1.60 V

      V  =  0.2203 L  <<<  round for sig figs

A submarine containing 15,000L of air at an air pressure of 1.2atm breaks apart deep within the ocean, where pressures reach 250atm. What volume of air would escape out of the submarine at that depth?

    15000 X 1.2  =  250V

    V  =  72L

Answer 2

rather than memorize a handful of named variations of the ideal gas law and for what conditions they apply AND hope to God you pick the right one come test time... just do this

for all these 2 state gas law problems

.. (1) start with P1V1 / (n1T1) = P2V2 / (n2T2)

.. (2) rearrange for your desired variable

.. (3) identify and cancel anything held constant

.. (4) plug and chug.  remember T must be absolute

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first problem

start with 

.. P1V1 / (n1T1) = P2V2 / (n2T2).. .. . <== the ideal gas law

rearrange for new volume.. V2

.. V2 = V1 * (P1 / P2) * (T2 / T1) * (n2 / n1)

T and n aren't mentioned.. we assume they are constant and cancel them

.. V2 = V1 * (P1 / P2).. .. .. . .. . ... .... ..<== look familiar?

plug and chug

.. V2 = 0.05L * (7.05 atm / 1.60 atm)

.. V2 = 0.2L

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second problem.. faster now. 

P1V1/(n1T1) = P2V2 / (n2T2)

V2 = V1 * (P1 / P2) * (T2 / T1) * (n2 / n1)

V2 = V1 * (P1 / P2)

V2 = 15000L * (1.2atm / 250atm) = 72L

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see isn't that better than memorizing this

https://answers.yahoo.com/question/index?qid=20140...

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btw... a 200ft deep dive is a technical dive that requires mixed gases (trimix 20/40/40 for example) instead of compressed air.  It's not something an average scuba diver would ever try.