如何在python中获得化合物的分子量？

Question

用户输入一个公式，例如： C12H2COOH

我们必须计算它的分子量，因为 C = 12.01，H = 1.008 和 O = 16。我们被告知要小心后面有两位数的元素和后面没有数字的元素。该程序还会不断询问化学式，并在您按回车键时退出。

我试过使用字典、for 循环和 while 循环。我已经计算了元素后的个位数化合物，例如 C2H2 但如果我在元素旁边放置两位数或不放置任何数字，它将失败。我也在研究如何在不删除分隔符的情况下分隔字符串作为一种可能的途径？你们将如何解决这个问题？任何帮助将不胜感激，谢谢！

这是我到目前为止所拥有的。很乱。

 xxx = ["H", "C", "O"]
elements = set(xxx)
while(True):
    chemical_formula = input("Enter chemical formula, or enter to quit: ")
    if chemical_formula == "":
        break
    else:
        characters = list(chemical_formula)
        n = 0
        print(characters)
        for i in characters:
            if characters[n] == "C":
                c = 12.0107
                if elements.intersection(set(characters[n+1])):
                    print(c)
                else:
                    number = int(characters[n+1])
                    print(number*c)

            elif characters[n] == "H":
                h = 1.00794
                if elements.intersection(set(characters[n+1])):
                    print(h)
                else:
                    number = int(characters[n+1])
                    print(number*h)

            elif characters[n] == "O":
                o = 15.9994
                if elements.intersection(set(characters[n+1])):
                    print(c)
                else:
                    number = int(characters[n+1])
                    print(number*o)
            else:
                numero = int(i)
                print(i*0)

            n = n+1

原文由 Francis Bautista 发布，翻译遵循 CC BY-SA 4.0 许可协议

Answer 1

编辑： 更新了 GitHub Gist

我整个夏天都在上 12 年级的化学课程，我也想这样做。我想到了一种不同的方法，这里是版本 1（’ZERO’ 只是一个地方 Holder 我只是没有用”测试）我检查了 C12H2COOH 并给出了正确的答案（191.16 g/mol）。希望这可以帮助某人：

 __version__ = '1.2.1'
"""
=================================
Molar Mass Calculator
Author: Elijah Lopez
Version: 1.2.1
Last Updated: April 4th 2020
Created: July 8th 2017
Python Version: 3.6+
=================================
"""
MM_of_Elements = {'H': 1.00794, 'He': 4.002602, 'Li': 6.941, 'Be': 9.012182, 'B': 10.811, 'C': 12.0107, 'N': 14.0067,
                  'O': 15.9994, 'F': 18.9984032, 'Ne': 20.1797, 'Na': 22.98976928, 'Mg': 24.305, 'Al': 26.9815386,
                  'Si': 28.0855, 'P': 30.973762, 'S': 32.065, 'Cl': 35.453, 'Ar': 39.948, 'K': 39.0983, 'Ca': 40.078,
                  'Sc': 44.955912, 'Ti': 47.867, 'V': 50.9415, 'Cr': 51.9961, 'Mn': 54.938045,
                  'Fe': 55.845, 'Co': 58.933195, 'Ni': 58.6934, 'Cu': 63.546, 'Zn': 65.409, 'Ga': 69.723, 'Ge': 72.64,
                  'As': 74.9216, 'Se': 78.96, 'Br': 79.904, 'Kr': 83.798, 'Rb': 85.4678, 'Sr': 87.62, 'Y': 88.90585,
                  'Zr': 91.224, 'Nb': 92.90638, 'Mo': 95.94, 'Tc': 98.9063, 'Ru': 101.07, 'Rh': 102.9055, 'Pd': 106.42,
                  'Ag': 107.8682, 'Cd': 112.411, 'In': 114.818, 'Sn': 118.71, 'Sb': 121.760, 'Te': 127.6,
                  'I': 126.90447, 'Xe': 131.293, 'Cs': 132.9054519, 'Ba': 137.327, 'La': 138.90547, 'Ce': 140.116,
                  'Pr': 140.90465, 'Nd': 144.242, 'Pm': 146.9151, 'Sm': 150.36, 'Eu': 151.964, 'Gd': 157.25,
                  'Tb': 158.92535, 'Dy': 162.5, 'Ho': 164.93032, 'Er': 167.259, 'Tm': 168.93421, 'Yb': 173.04,
                  'Lu': 174.967, 'Hf': 178.49, 'Ta': 180.9479, 'W': 183.84, 'Re': 186.207, 'Os': 190.23, 'Ir': 192.217,
                  'Pt': 195.084, 'Au': 196.966569, 'Hg': 200.59, 'Tl': 204.3833, 'Pb': 207.2, 'Bi': 208.9804,
                  'Po': 208.9824, 'At': 209.9871, 'Rn': 222.0176, 'Fr': 223.0197, 'Ra': 226.0254, 'Ac': 227.0278,
                  'Th': 232.03806, 'Pa': 231.03588, 'U': 238.02891, 'Np': 237.0482, 'Pu': 244.0642, 'Am': 243.0614,
                  'Cm': 247.0703, 'Bk': 247.0703, 'Cf': 251.0796, 'Es': 252.0829, 'Fm': 257.0951, 'Md': 258.0951,
                  'No': 259.1009, 'Lr': 262, 'Rf': 267, 'Db': 268, 'Sg': 271, 'Bh': 270, 'Hs': 269, 'Mt': 278,
                  'Ds': 281, 'Rg': 281, 'Cn': 285, 'Nh': 284, 'Fl': 289, 'Mc': 289, 'Lv': 292, 'Ts': 294, 'Og': 294,
                  '': 0}

def molar_mass(compound: str, decimal_places=None) -> float:
    is_polyatomic = end = multiply = False
    polyatomic_mass, m_m, multiplier = 0, 0, 1
    element = ''

    for e in compound:
        if is_polyatomic:
            if end:
                is_polyatomic = False
                m_m += int(e) * polyatomic_mass if e.isdigit() else polyatomic_mass + MM_of_Elements[e]
            elif e.isdigit():
                multiplier = int(str(multiplier) + e) if multiply else int(e)
                multiply = True
            elif e.islower():
                element += e
            elif e.isupper():
                polyatomic_mass += multiplier * MM_of_Elements[element]
                element, multiplier, multiply = e, 1, False
            elif e == ')':
                polyatomic_mass += multiplier * MM_of_Elements[element]
                element, multiplier = '', 1
                end, multiply = True, False
        elif e == '(':
            m_m += multiplier * MM_of_Elements[element]
            element, multiplier = '', 1
            is_polyatomic, multiply = True, False
        elif e.isdigit():
            multiplier = int(str(multiplier) + e) if multiply else int(e)
            multiply = True
        elif e.islower():
            element += e
        elif e.isupper():
            m_m += multiplier * MM_of_Elements[element]
            element, multiplier, multiply = e, 1, False
    m_m += multiplier * MM_of_Elements[element]
    if decimal_places is not None:
        return round(m_m, decimal_places)
    return m_m

原文由 Elijah 发布，翻译遵循 CC BY-SA 4.0 许可协议