Template:Chem molar mass

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This template calculates the molecular mass (or molar mass) of a chemical compound. It is designed to be embedded in infoboxes {{Infobox drug}} and {{Chembox}}, but it can be used in-line just as well.

Parameters

Use chemical symbols to compose the molecular formula: {{Chem molar mass|H=2|O=1}} (for H
₂O) → 18.02 g·mol⁻¹

|round= by default the calculated number is rounded to 2 decimals.

|round=no will show all decimals:

{{Chem molar mass|Be=1|round=no}} → 9.0121831 g·mol⁻¹

|round=a number will round to that number of decimals

{{Chem molar mass|Be=1|round=4}} → 9.0122 g·mol⁻¹

|unit= changes the unit for the calculated result. The default unit is g·mol⁻¹.

{{Chem molar mass|H=2|O=1|unit=gram per mole}} → 18.02 gram per mole

The next parameters will always show:
|fixed= to enter a fixed (predefined) value+unit. It will overwrite any calculated value+unit.

|ref=<ref>some source</ref> will add the reference right after the unit.

|comment=Any textis added as a suffix, after a space and unedited (no brackets added etc.).

Example:

{{Chem molar mass|fixed=234.56 g·mol<sup>−1</sup>|ref=<ref>Some source</ref>|comment=My Comment}} → 234.56 g·mol⁻¹^[1] My Comment

|sortable=yes, for use in sortable tables: will add a hidden sortable number, and omits the unit (see table below).

Blank parameter list

{{Chem molar mass
| round   =
| unit    =
| fixed   =
| ref     =
| comment =
| sortable=
| catname =
}}

{{Chem molar mass
<!-- with 118 chemical symbols: -->|H= |He= |Li= |Be= |B= |C= |N= |O= |F= |Ne= |Na= |Mg= |Al= |Si= |P= |S= |Cl= |Ar= |K= |Ca= |Sc= |Ti= |V= |Cr= |Mn= |Fe= |Co= |Ni= |Cu= |Zn= |Ga= |Ge= |As= |Se= |Br= |Kr= |Rb= |Sr= |Y= |Zr= |Nb= |Mo= |Tc= |Ru= |Rh= |Pd= |Ag= |Cd= |In= |Sn= |Sb= |Te= |I= |Xe= |Cs= |Ba= |La= |Ce= |Pr= |Nd= |Pm= |Sm= |Eu= |Gd= |Tb= |Dy= |Ho= |Er= |Tm= |Yb= |Lu= |Hf= |Ta= |W= |Re= |Os= |Ir= |Pt= |Au= |Hg= |Tl= |Pb= |Bi= |Po= |At= |Rn= |Fr= |Ra= |Ac= |Th= |Pa= |U= |Np= |Pu= |Am= |Cm= |Bk= |Cf= |Es= |Fm= |Md= |No= |Lr= |Rf= |Db= |Sg= |Bh= |Hs= |Mt= |Ds= |Rg= |Cn= |Nh= |Lv= |Mc= |Fl= |Ts= |Og=
| round   =
| unit    =
| fixed   =
| ref     =
| comment =
| sortable=
| catname =
}}

Standard atomic weights used

Atomic number Z	Element	Molar mass g·mol⁻¹	Formal standard atomic weight (A_{r, standard})^[2]	s.a.w., formal short (A_{r, abridged and conventional})^[2]	Note

	C ₉H ₈O ₄	180.157			calculated from formula
	C ₉H ₈O ₄	180.157 g·mol⁻¹			calculated from formula
	C ₉H ₈O ₄	180.159			aspirin
1	H	1.008	[1.00784, 1.00811]	1.008
2	He	4.002602	4.002602(2)	4.0026
3	Li	6.94	[6.938, 6.997]	6.94
4	Be	9.0121831	9.0121831(5)	9.0122
5	B	10.81	[10.806, 10.821]	10.81
6	C	12.011	[12.0096, 12.0116]	12.011
7	N	14.007	[14.00643, 14.00728]	14.007
8	O	15.999	[15.99903, 15.99977]	15.999
9	F	18.998403163	18.998403163(6)	18.998
10	Ne	20.1797	20.1797(6)	20.180
11	Na	22.98976928	22.98976928(2)	22.990
12	Mg	24.305	[24.304, 24.307]	24.305
13	Al	26.9815385	26.9815384(3)	26.982
14	Si	28.085	[28.084, 28.086]	28.085
15	P	30.973761998	30.973761998(5)	30.974
16	S	32.06	[32.059, 32.076]	32.06
17	Cl	35.45	[35.446, 35.457]	35.45
18	Ar	39.948	[39.792, 39.963]	39.95
19	K	39.0983	39.0983(1)	39.098
20	Ca	40.078	40.078(4)	40.078(4)
21	Sc	44.955908	44.955908(5)	44.956
22	Ti	47.867	47.867(1)	47.867
23	V	50.9415	50.9415(1)	50.942
24	Cr	51.9961	51.9961(6)	51.996
25	Mn	54.938044	54.938043(2)	54.938
26	Fe	55.845	55.845(2)	55.845(2)
27	Co	58.933194	58.933194(3)	58.933
28	Ni	58.6934	58.6934(4)	58.693
29	Cu	63.546	63.546(3)	63.546(3)
30	Zn	65.38	65.38(2)	65.38(2)
31	Ga	69.723	69.723(1)	69.723
32	Ge	72.63	72.630(8)	72.630(8)
33	As	74.921595	74.921595(6)	74.922
34	Se	78.971	78.971(8)	78.971(8)
35	Br	79.904	[79.901, 79.907]	79.904
36	Kr	83.798	83.798(2)	83.798(2)
37	Rb	85.4678	85.4678(3)	85.468
38	Sr	87.62	87.62(1)	87.62
39	Y	88.90584	88.90584(1)	88.906
40	Zr	91.224	91.224(2)	91.224(2)
41	Nb	92.90637	92.90637(1)	92.906
42	Mo	95.95	95.95(1)	95.95
43	Tc	98
44	Ru	101.07	101.07(2)	101.07(2)
45	Rh	102.9055	102.90549(2)	102.91
46	Pd	106.42	106.42(1)	106.42
47	Ag	107.8682	107.8682(2)	107.87
48	Cd	112.414	112.414(4)	112.41
49	In	114.818	114.818(1)	114.82
50	Sn	118.71	118.710(7)	118.71
51	Sb	121.76	121.760(1)	121.76
52	Te	127.6	127.60(3)	127.60(3)	(Does not follow atomic number)
53	I	126.90447	126.90447(3)	126.90	(Does not follow atomic number)
54	Xe	131.293	131.293(6)	131.29
55	Cs	132.90545196	132.90545196(6)	132.91
56	Ba	137.327	137.327(7)	137.33
57	La	138.90547	138.90547(7)	138.91
58	Ce	140.116	140.116(1)	140.12
59	Pr	140.90766	140.90766(1)	140.91
60	Nd	144.242	144.242(3)	144.24
61	Pm	145
62	Sm	150.36	150.36(2)	150.36(2)
63	Eu	151.964	151.964(1)	151.96
64	Gd	157.25	157.25(3)	157.25(3)
65	Tb	158.92535	158.925354(8)	158.93
66	Dy	162.5	162.500(1)	162.50
67	Ho	164.93033	164.930328(7)	164.93
68	Er	167.259	167.259(3)	167.26
69	Tm	168.93422	168.934218(6)	168.93
70	Yb	173.045	173.045(10)	173.05
71	Lu	174.9668	174.9668(1)	174.97
72	Hf	178.49	178.486(6)	178.49(2)
73	Ta	180.94788	180.94788(2)	180.95
74	W	183.84	183.84(1)	183.84
75	Re	186.207	186.207(1)	186.21
76	Os	190.23	190.23(3)	190.23(3)
77	Ir	192.217	192.217(2)	192.22
78	Pt	195.084	195.084(9)	195.08
79	Au	196.966569	196.966570(4)	196.97
80	Hg	200.592	200.592(3)	200.59
81	Tl	204.38	[204.382, 204.385]	204.38
82	Pb	207.2	[206.14, 207.94]	207.2
83	Bi	208.9804	208.98040(1)	208.98
84	Po	209
85	At	210
86	Rn	222
87	Fr	223
88	Ra	226
89	Ac	227
90	Th	232.0377	232.0377(4)	232.04
91	Pa	231.03588	231.03588(1)	231.04
92	U	238.02891	238.02891(3)	238.03
93	Np	237
94	Pu	244
95	Am	243
96	Cm	247
97	Bk	247
98	Cf	251
99	Es	252
100	Fm	257
101	Md	258
102	No	259
103	Lr	266
104	Rf	267
105	Db	268
106	Sg	269
107	Bh	270
108	Hs	269
109	Mt	278
110	Ds	281
111	Rg	281
112	Cn	285
113	Nh	286
114	Fl	289
115	Mc	289
116	Lv	293
117	Ts	294
118	Og	294

Data sources (CIAAW)

Primarily, the atomic weights used here are defined by CIAAW [1]:

"Standard Atomic Weights". Commission on Isotopic Abundances and Atomic Weights (CIAAW). 2015. Retrieved 2015-09-20. (68 elements)
CIAAW also published additional lists in spreadsheet format (2013). It has additional conventional values for trade usage, and some background information on the numbers and calculations. (12 elements: B, Br, C, Cl, H, Li, Mg, N, O, S, Si, Tl).

Coplen, T.B.; et al. (2013). "Atomic weights of the elements 2013 (xls)". CIAAW. Retrieved 2015-05-26.

Some unstable elements can naturally occur, and so are listed (4 elements: Bi, Th, Pa, U)
Additional values are those of the most stable isotopes, as given in List of chemical elements (34 elements). This source is not supported by the CIAAW publications.

See also: "Atomic weights of the elements 2013 (IUPAC Technical Report)". Pure and Applied Chemistry. February 2016. pp. 265–291. doi:10.1515/pac-2015-0305. eISSN 1365-3075. ISSN 0033-4545. Retrieved 2016-12-29.

Possolo, Antonio; van der Veen, Adriaan M. H.; Meija, Juris; Hibbert, D. Brynn (2018-01-04). "Interpreting and propagating the uncertainty of the standard atomic weights (IUPAC Technical Report)". doi:10.1515/pac-2016-0402. Retrieved 2018-09-23.

Embedding in a template

The template is designed to be embedded in a template like {{Drugbox}}. The molecular formula can be entered like ...|H=2|O=1, and these values then are passed through to this subtemplate, together with the other parameters like |round=.

For this usage one extra parameter is available:
|catname=. A category name entered here, which will be used as maintenance category for articles that have both calculated and fixed input. These are two inputs for one data value. The maintenance task is to remove the |fixed= input (unless overwriting is intentional).

Know issue: uncertainty

Atomic weights are given with a precision and uncertainty, for example: 20.1797(6) for neon (more here).

Uncertainty

This template does not maintain the uncertainty (the bracketed part). When done correctly, the uncertainty could influence the result, especially when precision (number of decimals) is larger.

Rounding

This template usually does rounding on the calculated result, to 2 decimals by default:

For neon: {{Chem molar mass|Ne=1}} → 20.18 g·mol⁻¹

Two decimals is common practice for trade and most laboratory situations. However, rounding is set to more decimals, and the compounnd has atoms with less precision, the resulting number will be inaccurate (suggesting a wrong precision). For example strontium :

{{Chem molar mass|Sr=1|round=4}} → 87.6200 g·mol⁻¹

Six elements have values ending with a final decimal being "0" (a zero), like Sn: 118.710. This value does not show for technical reasons (the calculation 'rounds them away'), but it does signify an extra precision. The six elements are Sn, Rh, Ge, Sb, Dy, Bi.

Calculate cumulative uncertainties

[2], [3]