Chemical Formula Manipulation

ChemistryLab allows you to create and manipulate chemical formulas. It is based on Formula which is a structure (struct) which contains an expression, a writing of the formula close to those found in the Phreeqc databases, a unicode expression as well as a composition in the form of dictionaries and a charge.

struct Formula{T<:Number}
    expr::String
    phreeqc::String
    unicode::String
    colored::String
    composition::OrderedDict{Symbol,T}
    charge::Int8
end

Formula construction

Formulas can be constructed:

• by parsing a string containing eventually fractional or decimal coefficients

fgen = Formula("C3AFS5//8H4.32")

Formula{Real}
    formula: C3AFS5//8H4.32 ◆ C₃AFS⅝H₄.₃₂ ◆ C₃AFS⅝H₄.₃₂
composition: C => 3, A => 1, F => 1, S => 5//8, H => 4.32
     charge: 0

• from symbols representing atoms

fCO2 = :C + 2 * :O

Formula{Int64}
    formula: CO2 ◆ CO₂ ◆ CO₂
composition: O => 2, C => 1
     charge: 0

Charges can also be included during the creation in two different ways:

fHSO₄⁻ = :H+:S+4*:O+:e

Formula{Int64}
    formula: HSO4- ◆ HSO₄- ◆ HSO₄⁻
composition: H => 1, S => 1, O => 4
     charge: -1

Or:

fNa⁺ = :Na+:Zz

Formula{Int64}
    formula: Na+ ◆ Na⁺
composition: Na => 1
     charge: 1

Type of Formula

The type of the Formula struct being associated with the most complex type of the set of coefficients.

typeof(Formula("H2O"))

Formula{Int64}

typeof(Formula("C3AFS5//8H4.32"))

Formula{Real}

Change of type

Coefficient types can be converted a posteriori.

convert(Float64, Formula("H2O"))

Formula{Float64}
    formula: H2O ◆ H₂O ◆ H₂O
composition: H => 2.0, O => 1.0
     charge: 0