[英]How to balance a chemical equation in Python 2.7 Using matrices
I have a college assignment where I must balance the following equation : 我有一个大学作业,我必须平衡以下等式:
NaOH + H2S04 --> Na2S04 + H20 NaOH + H 2 SO 4→Na 2 SO 4 + H 2 O.
my knowledge of python and coding in general is extremely limited at the moment. 我对python和编码的了解目前非常有限。 So far I have attempted to use matrices to solve the equation.
到目前为止,我已经尝试使用矩阵来解决这个问题。 It looks like I am getting the solution a=b=x=y=0 I guess I need to set one of the variables to 1 and solve for the other three.
看起来我得到的解决方案a = b = x = y = 0我想我需要将其中一个变量设置为1并解决其他三个变量。 I'm not sure how to go about doing this, I have had a search, it looks like other people have used more sophisticated code and I'm not really able to follow it!
我不知道如何去做这个,我有一个搜索,看起来其他人已经使用了更复杂的代码,我真的无法遵循它!
here's what I have so far 这是我到目前为止所拥有的
#aNaOH + bH2S04 --> xNa2SO4 +y H20
#Na: a=2x
#O: a+4b=4x+y
#H: a+2h = 2y
#S: b = x
#a+0b -2x+0y = 0
#a+4b-4x-y=0
#a+2b+0x-2y=0
#0a +b-x+0y=0
A=array([[1,0,-2,0],
[1,4,-4,-1],
[1,2,0,-2],
[0,1,-1,0]])
b=array([0,0,0,0])
c =linalg.solve(A,b)
print c
0.0.0.0
The problem is that you have constructed a linear system with b being a zero-vector . 问题是你已经构建了一个线性系统,其中b是零向量 。 Now for such system there is always the straight-forward answer that all variables are zeros as well.
现在对于这样的系统,总是有直接的答案,即所有变量也都是零。 Since multiplying a number with zero and adding zeros up results always in zeros.
由于将数字乘以零并向上添加零,结果始终为零。
A solution might be to assign 1 to a variable . 解决方案可能是将1分配给变量 。 Take for instance
a
. 就拿
a
。 If we assign a = 1
, then we will get b
, x
and y
in function of a
being 1. 如果我们分配
a = 1
,那么我们将得到b
, x
和y
中的功能a
是1。
So now or linear system is: 所以现在或线性系统是:
B X Y | #
2 |1 # A = 2X
-4 4 1 |1 # A+4B = 4X+4Y
-2 2 |1 # A+2B = 2Y
-1 1 0 |0 # B = X
Or putting it into code: 或者将其放入代码中:
>>> A = array([[0,2,0],[-4,4,1],[-2,0,2],[-1,1,0]])
>>> B = array([1,1,1,0])
>>> linalg.lstsq(A,B)
(array([ 0.5, 0.5, 1. ]), 6.9333477997940491e-33, 3, array([ 6.32979642, 2.5028631 , 0.81814033]))
So that means that: 这意味着:
A = 1, B = 0.5, X = 0.5, Y = 1.
If we multiply this by 2, we get: 如果我们乘以2,我们得到:
2 NaOH + H2S04 -> Na2S04 + 2 H20
Which is correct. 哪个是对的。
I referred to Solve system of linear integer equations in Python which translated into 我在Python中提到了Solve系统的线性整数方程式
# Find minimum integer coefficients for a chemical reaction like
# A * NaOH + B * H2SO4 -> C * Na2SO4 + D * H20
import sympy
import re
# match a single element and optional count, like Na2
ELEMENT_CLAUSE = re.compile("([A-Z][a-z]?)([0-9]*)")
def parse_compound(compound):
"""
Given a chemical compound like Na2SO4,
return a dict of element counts like {"Na":2, "S":1, "O":4}
"""
assert "(" not in compound, "This parser doesn't grok subclauses"
return {el: (int(num) if num else 1) for el, num in ELEMENT_CLAUSE.findall(compound)}
def main():
print("\nPlease enter left-hand list of compounds, separated by spaces:")
lhs_strings = input().split()
lhs_compounds = [parse_compound(compound) for compound in lhs_strings]
print("\nPlease enter right-hand list of compounds, separated by spaces:")
rhs_strings = input().split()
rhs_compounds = [parse_compound(compound) for compound in rhs_strings]
# Get canonical list of elements
els = sorted(set().union(*lhs_compounds, *rhs_compounds))
els_index = dict(zip(els, range(len(els))))
# Build matrix to solve
w = len(lhs_compounds) + len(rhs_compounds)
h = len(els)
A = [[0] * w for _ in range(h)]
# load with element coefficients
for col, compound in enumerate(lhs_compounds):
for el, num in compound.items():
row = els_index[el]
A[row][col] = num
for col, compound in enumerate(rhs_compounds, len(lhs_compounds)):
for el, num in compound.items():
row = els_index[el]
A[row][col] = -num # invert coefficients for RHS
# Solve using Sympy for absolute-precision math
A = sympy.Matrix(A)
# find first basis vector == primary solution
coeffs = A.nullspace()[0]
# find least common denominator, multiply through to convert to integer solution
coeffs *= sympy.lcm([term.q for term in coeffs])
# Display result
lhs = " + ".join(["{} {}".format(coeffs[i], s) for i, s in enumerate(lhs_strings)])
rhs = " + ".join(["{} {}".format(coeffs[i], s) for i, s in enumerate(rhs_strings, len(lhs_strings))])
print("\nBalanced solution:")
print("{} -> {}".format(lhs, rhs))
if __name__ == "__main__":
main()
which runs like 哪个像
Please enter left-hand list of compounds, separated by spaces:
NaOH H2SO4
Please enter right-hand list of compounds, separated by spaces:
Na2SO4 H2O
Balanced solution:
2 NaOH + 1 H2SO4 -> 1 Na2SO4 + 2 H2O
You can use this solution. 您可以使用此解决方案。 It works with any chemical equation.
它适用于任何化学方程式。 The last coefficient can be calculated with a row where b[i]!=0
最后一个系数可以用行计算,其中b [i]!= 0
H2SO4+NaOH−−>Na2SO4+H2OH2SO4+NaOH−−>Na2SO4+H2O H 2 SO 4 +的NaOH - >硫酸钠+ H2OH2SO4 +的NaOH - >硫酸钠+ H 2 O
a=np.array([[2,1,0],[1,0,-1],[4,1,-4],[0,1,-2]])
b=np.array([2,0,1,0])
x=np.linalg.lstsq(a,b,rcond=None)[0]
print(x)
y=sum(x*a[0])/b[0]
print("y=%f"%y)
out: 出:
[0.5 1. 0.5] y=1.000000 [0.5 1. 0.5] y = 1.000000
Very well done. 干的很好。 However, when I tested this snippet on the following equation taken from David Lay's Linear Algebra textbook, the 5th edition I received a sub-optimal solution that can be further simplified.
然而,当我使用David Lay的线性代数教科书中的以下等式测试这个片段时,第5版我收到了一个可以进一步简化的次优解决方案。
On p. 在p。 55, 1.6 Exercises check ex 7.:
55,1.6练习检查前7:
NaHCO_3 + H_3C_6H_5O_7 --> Na_3C_6H_5O_7 + H_2O + CO_2 NaHCO_3 + H_3C_6H_5O_7 - > Na_3C_6H_5O_7 + H_2O + CO_2
Your snippet returns: 您的代码段返回:
Balanced solution: 平衡解决方案:
15NaHCO3 + 6H3C6H5O7 -> 5Na3C6H5O7 + 10H2O + 21CO2 15NaHCO3 + 6H3C6H5O7 - > 5Na3C6H5O7 + 10H2O + 21CO2
The correct answer is: 正确答案是:
3NaHCO_3 + H_3C_6H_5O_7 -> Na_3C_6H_5O_7 + 3H_2O + 3CO_2
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