Isobaric transition, first law: <span>H=ΔU+w</span>
for a gas expansion: <span>w=<span>P<span>ext</span></span>∗ΔV</span>
to convert to joules, you need the gas constants.
R = 0.08206 L atm/mol*K, R=8.314 J/mol*K
<span>w=<span>P<span>ext</span></span>∗ΔV∗<span><span>8.314 J/mol∗K</span><span>0.08206 L atm/mol∗K</span></span></span>
<span>ΔU=ΔH−[<span>P<span>ext</span></span>∗ΔV∗<span><span>8.314 J/mol∗K</span><span>0.08206 L atm/mol∗K</span></span>]</span>
<span>ΔU=−75000 J−[(43.0atm)∗(2−5)L∗<span><span>8.314 J</span><span>0.08206 L atm</span></span>]</span>
Then you need to convert to kJ.
by the way U=E, internal energy.
M1v1=m2v2 m2=(m1v1)/v2 Where m is the molarities and v is the volumes <span>m2=(25.0*0.500)/53.5 m2=12.5/53.5 m2=0.2336 by rounding off: m2=0.234 M so the answer is C: 0.234 M</span>