def build_molecular_formula(elements):
    formula = ''.join([f"{element[0]}{element[1]}" for element in elements])
    return formula

# 示例
compounds = [
    [('C', 1), ('H', 2)],
    [('C', 1), ('H', 2), ('O', 1)],
    [('Cl', 2), ('Ca', 1)]
]

for compound in compounds:
    print(build_molecular_formula(compound))

def get_valence(element):
    valences = {
        'H': ('+1', 'HCl'),
        'O': ('-2', 'H2O'),
        'Na': ('+1', 'NaCl'),
        'Cl': ('-1', 'NaCl')
    }
    return valences.get(element, '未知元素')

# 示例
elements = ['H', 'O', 'Na', 'Cl']
for element in elements:
    valence, example = get_valence(element)
    print(f"{element}: {valence} (如{example})")

import re

def parse_molecular_formula(formula):
    pattern = r'([A-Z][a-z]*)(\d*)'
    matches = re.findall(pattern, formula)
    result = {}
    
    for element, count in matches:
        result[element] = int(count) if count else 1
    
    return result

# 示例
formula = "C6H12O6"
print(parse_molecular_formula(formula))

from collections import Counter

def parse_reaction(reaction):
    reactants, products = reaction.split('->')
    reactants = reactants.split('+')
    products = products.split('+')
    
    def count_elements(compounds):
        total_count = Counter()
        for compound in compounds:
            parsed = parse_molecular_formula(compound.strip())
            total_count.update(parsed)
        return total_count
    
    reactant_count = count_elements(reactants)
    product_count = count_elements(products)
    
    return reactant_count == product_count, reactant_count, product_count

# 示例
reaction = "C3H8 + O2 -> CO2 + H2O"
balanced, reactants, products = parse_reaction(reaction)
print(f"反應(yīng)方程式是否平衡: {balanced}")
print(f"反應(yīng)物元素?cái)?shù)量: {reactants}")
print(f"生成物元素?cái)?shù)量: {products}")

def calculate_molar_mass(formula, atomic_weights):
    parsed_formula = parse_molecular_formula(formula)
    molar_mass = sum(atomic_weights[element] * count for element, count in parsed_formula.items())
    return molar_mass

# 示例
atomic_weights = {'H': 1.008, 'C': 12.011, 'O': 15.999, 'N': 14.007}
formula = "C6H12O6"
print(f"{formula} 的摩爾質(zhì)量: {calculate_molar_mass(formula, atomic_weights)} g/mol")

def calculate_mass_fraction(formula, element, atomic_weights):
    molar_mass = calculate_molar_mass(formula, atomic_weights)
    parsed_formula = parse_molecular_formula(formula)
    element_mass = atomic_weights[element] * parsed_formula[element]
    
    mass_fraction = element_mass / molar_mass
    return mass_fraction

# 示例
atomic_weights = {'H': 1.008, 'C': 12.011, 'O': 15.999}
formula = "C6H12O6"
element = 'C'
print(f"{element} 在 {formula} 中的質(zhì)量分?jǐn)?shù): {calculate_mass_fraction(formula, element, atomic_weights):.2%}")

def calculate_reaction_heat(reactants_heat, products_heat):
    total_reactants_heat = sum(reactants_heat)
    total_products_heat = sum(products_heat)
    reaction_heat = total_products_heat - total_reactants_heat
    return reaction_heat

# 示例
reactants_heat = [0, -285.8]  # H2 + 1/2 O2 -> H2O
products_heat = [-285.8]
reaction_heat = calculate_reaction_heat(reactants_heat, products_heat)
print(f"反應(yīng)熱: {reaction_heat} kJ/mol")

import math

def calculate_pH(concentration):
    if concentration <= 0:
        raise ValueError("濃度必須大于零")
    pH = -math.log10(concentration)
    return pH

# 示例
concentration = 0.01  # 0.01 M HCl
pH_value = calculate_pH(concentration)
print(f"濃度為 {concentration} M 的溶液的pH值: {pH_value:.2f}")