View source for Properties (Molecular Weight)

== Description ==

This article describes a method for retrieving the '''molecular weight''' of chemical compounds.

== Model theory ==

{| style="float:right; margin-left: 10px;"; class="wikitable"
|+ Table 1. Atomic weight.{{KWA Kenwalt Australia Pty Ltd (2021)}}
!Element || Atomic weight (g/mol)
|-
| Ac || 227
|-
| Ag || 107.8682
|-
| Al || 26.9815384
|-
| Am || 243
|-
| Ar || 39.948
|-
| As || 74.921595
|-
| At || 210
|-
| Au || 196.96657
|-
| B || 10.811
|-
| Ba || 137.327
|-
| Be || 9.0121831
|-
| Bi || 208.9804
|-
| Bk || 247
|-
| Br || 79.904
|-
| C || 12.0107
|-
| Ca || 40.078
|-
| Cd || 112.414
|-
| Ce || 140.116
|-
| Cf || 251
|-
| Cl || 35.453
|-
| Cm || 247
|-
| Co || 58.933194
|-
| Cr || 51.9961
|-
| Cs || 132.90545196
|-
| Cu || 63.546
|-
| Dy || 162.5
|-
| Er || 167.259
|-
| Es || 252
|-
| Eu || 151.964
|-
| F || 18.998403163
|-
| Fe || 55.845
|-
| Fm || 257
|-
| Fr || 223
|-
| Ga || 69.723
|-
| Gd || 157.25
|-
| Ge || 72.63
|-
| H || 1.00794
|-
| He || 4.002602
|-
| Hf || 178.486
|-
| Hg || 200.592
|-
| Ho || 164.930328
|-
| I || 126.90447
|-
| In || 114.818
|-
| Ir || 192.217
|-
| K || 39.0983
|-
| Kr || 83.798
|-
| La || 138.90547
|-
| Li || 6.941
|-
| Lr || 262
|-
| Lu || 174.9668
|-
| Md || 258
|-
| Mg || 24.305
|-
| Mn || 54.938043
|-
| Mo || 95.95
|-
| N || 14.0067
|-
| Na || 22.98976928
|-
| Nb || 92.90637
|-
| Nd || 144.242
|-
| Ne || 20.1797
|-
| Ni || 58.6934
|-
| No || 259
|-
| Np || 237
|-
| O || 15.9994
|-
| Os || 190.23
|-
| P || 30.973761998
|-
| Pa || 231.03588
|-
| Pb || 207.2
|-
| Pd || 106.42
|-
| Pm || 145
|-
| Po || 209
|-
| Pr || 140.90766
|-
| Pt || 195.084
|-
| Pu || 244
|-
| Ra || 226
|-
| Rb || 85.4678
|-
| Re || 186.207
|-
| Rh || 102.90549
|-
| Rn || 222
|-
| Ru || 101.07
|-
| S || 32.065
|-
| Sb || 121.76
|-
| Sc || 44.955908
|-
| Se || 78.971
|-
| Si || 28.0855
|-
| Sm || 150.36
|-
| Sn || 118.71
|-
| Sr || 87.62
|-
| Ta || 180.94788
|-
| Tb || 158.925354
|-
| Tc || 98
|-
| Te || 127.6
|-
| Th || 232.0377
|-
| Ti || 47.867
|-
| Tl || 204.3833
|-
| Tm || 168.934218
|-
| U || 238.02891
|-
| V || 50.9415
|-
| W || 183.84
|-
| Xe || 131.293
|-
| Y || 88.90584
|-
| Yb || 173.045
|-
| Zn || 65.38
|-
| Zr || 91.224
|}

This function returns the molecular weight of a chemical compound based on the atomic weights of its constituent elements.

The following applies to use of the molecular weight function:
* The atomic weights of the elements which are used by the function are presented in Table 1.{{KWA Kenwalt Australia Pty Ltd (2021)}}
* Only alphanumeric characters are allowed in the molecule definition
* Only stoichiometric (integer) counts of elements are permitted; no fractions or decimals
* Bracket notation is permitted
* Nested brackets are permitted
* Dot notation is not permitted; use brackets instead

== Excel ==

The molecular weight calculation may be invoked from the Excel formula bar with the following function call:

<syntaxhighlight lang="vb">=mdProps_MW(Formula as String, Optional returnElementCount as Boolean = false)</syntaxhighlight>

{{Excel (Text, Help, No Arguments)}}

The input parameters and calculation results are defined below in matrix notation, along with an example image showing the selection of the same cells and arrays in the Excel interface:

{| 
|- style="vertical-align:top;"
|
  {| 
  |- style="vertical-align:top;"
  |
:<math>
   \begin{align}
   \mathit{Formula} & = \big [ s_{\rm m} \big ]\\
   \mathit{returnElementCount} & = \big [ \text{(True/False)} \big ]\\
   \end{align}</math>
  |<math>
   \mathit{mdProps\_MW}  = 
   \begin{bmatrix}
   {\rm MW}\text{ (g/mol)}\\
   {s_{\rm e}}^*\\
   \end{bmatrix}</math>
  |-  style="vertical-align:top;"
  |colspan="2"|
where:
* <math>s_{\rm m}</math> is a string of characters representing the molecular formula of the substance
* <math>\mathit{returnElementCount}</math> indicates whether to return a stoichiometric count of each element identified in the molecular formula (default is to omit)
* <math>{\rm MW}</math> is the molecular weight of the substance (g/mol)
* <math>s_{\rm e}</math> is a string of characters representing the stoichiometric count of each element identified in the molecular formula
* the <math>^*</math> superscript denotes an optionally-returned result
  |} 
|
:[[File:PropsMW1.png|frame|Figure 1. Example showing the selection of the input parameters (shaded blue frame), and Results (light blue frame) array in Excel. The parameter <math>\mathit{returnElementCount}=\text{True}</math> in this example.]]
|}

== References ==

[[Category:Excel]]