Chemical and Isotope Data
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Introduction
The ScientificConstants package contains chemical data
Use the GetElement command to access the properties of elements in the Periodic Table. For example, let's review the properties of Platinum (Pt).
withScientificConstants:
GetElementPt
78,symbol=Pt,name=platinum,names=platinum,ionizationenergy=value=8.9587,uncertainty=undefined,units=eV,electronegativity=value=2.28,uncertainty=undefined,units=1,boilingpoint=value=4098.,uncertainty=undefined,units=K,electronaffinity=value=2.128,uncertainty=0.002,units=eV,density=value=21.5,uncertainty=undefined,units=gcm3,atomicweight=value=195.078,uncertainty=0.002,units=amu,meltingpoint=value=2041.55,uncertainty=undefined,units=K
You can also extract the standard atomic weight of platinum.
evalfElementPt, atomicweight,units
3.239348611×10−25kg
With the GetIsotopes command, you can access all instances of platinum.
GetIsotopeselement=Pt
Pt168,Pt169,Pt170,Pt171,Pt172,Pt173,Pt174,Pt175,Pt176,Pt177,Pt178,Pt179,Pt180,Pt181,Pt182,Pt183,Pt184,Pt185,Pt186,Pt187,Pt188,Pt189,Pt190,Pt191,Pt192,Pt193,Pt194,Pt195,Pt196,Pt197,Pt198,Pt199,Pt200,Pt201,Pt202
Example - Molecular Weight
This example determines how many molecules of caffeine are in a 250 gram sample.
The chemical formula for caffeine is C8H12N4O2. Thus, the molecular weight is:
MW ≔ 8⋅ElementC, atomicweight+12⋅ElementH,atomicweight+4⋅ElementN,atomicweight+2⋅ElementO,atomicweight: evalfMW
3.258087476×10−25
which, in the current default system of units, SI, is measured in kilograms (kg). However, molecular weight is typically expressed in atomic mass units (amu). To convert a measurement between units, use the convert/units function.
MW__AMU≔convertMW, units, kg, amu
MW__AMU≔196.2064800
By definition, the number of atomic mass units per molecule is equal to the number of grams per mole. Hence, divide 250 by the above result.
NumMoles ≔ 250MW__AMU
NumMoles≔1.274167907
which is the number of moles in the sample.
To calculate the number of molecules, multiply the above result by Avogadro's constant.
NumMoles⋅evalfConstantN'A'
7.673218610×1023
Example - Radioactive Decay
The following example shows how to plot the decrease in the radioactive decay activity for a sample of radium-229.
The activity is
Activity ≔ A0⋅ⅇ−λ⋅t:
where, A0 is the initial activity, λ is the mean lifetime of the isotope, and t is the elapsed time.
The mean lifetime is related to the half-life by λ=0.693H
λ ≔ 0.693evalfElementRa229, halflife
λ≔0.002887500000
Plot with A0=1.
A0≔1:plotActivity, t=0..2⋅103, labels=Time (s), Activity, title=Radioactive Decay of Radium-229
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