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Scientists use carbon-14 to date ancient fossils.
Plants and animals absorb carbon-14 produced by cosmic rays. The ratio of C-14 to C-12 is constant when they are alive.
When they die, the C-14 decays to C-12, and the ratio changes.
Carbon-14 has a half-life of 5730 years. Thus, the object loses half its C-14 every 5730 years.
Scientists can use the C-14 to C-12 ratio to date fossils up to 70 000 years old.
The correct answer is option C.
1-hexene is an unsaturated hydrocarbon.
2-methylheptane
, 3-ethylpentane and cyclopentane have the suffix -ane, which means they are all alkanes . Alkanes do not have any unsaturation or double bonds.
1-hexene, has the suffix -ene, which means that it is an alkene. Alkanes do have unsaturation or double bonds. As the name indicates, 1-hexene has one double bond.
CH₂=CHCH₂CH₂CH₂CH₃
The differential change in entropy of a system is
given as: <span>
<span>dS = (∂S/∂T)_V dT </span>
We also know that </span>
<span>(∂S/∂T)_V = n*Cv/T, </span>
Where Cv is the molar heat capacity at constant
volume, and n is the number of moles. Combining the 2 equations:<span>
dS = n*Cv/T dT
Since Cv is constant as stated in the problem, therefore we
integrate the differential equation. Leading us to:
ΔS = n*Cv*ln(Tfinal/Tinitial)
<span>We are given that: V =
18L volume at P=2 kPa and T=298.15K. </span></span>
Using the ideal gas law to find the number of
moles of gas: <span>
n = p*V/R*T = (2kPa)*(18L)/((298.15K)*(8.314 L*kPa/(mol*K)))
n = 1.45*10^-2 mol
Going back to the entropy change:
ΔS = (1.45*10^-2 mol)*(20.17 J/(K*mol))*ln(1073.15/298.15)
<span>
<span>ΔS = 0.375 J/K</span></span></span>