Merge pull request #105 from KingsburyLab/bugfix

Solution.get_total_amount: bufix for mass based units

CHANGELOG.md

@@ -5,6 +5,13 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## Unreleased
+
+### Fixed
+
+- `Solution.get_total_amount`: Bugfix that would cause the method to fail if
+  mass-based units such as mg/L or ppm were requested.
+
 ## [0.12.0] - 2024-02-15
 
 ### Added
@@ -19,7 +26,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Fixed
 
-- `Solution.__add_`: Bugfix in the addition operation `+` that could cause problems with
+- `Solution.__add__`: Bugfix in the addition operation `+` that could cause problems with
   child classes (i.e., classes that inherit from `Solution`) to work improperly
 
 ### Changed

src/pyEQL/solution.py

@@ -1204,7 +1204,7 @@ def get_total_amount(self, element: str, units) -> Quantity:
                     "[mass]/[length]**3",
                     "[mass]/[mass]",
                 ):
-                    TOT += amt * ion.to_weight_dict["el"]  # returns {el: wt fraction}
+                    TOT += amt * ion.to_weight_dict[el]  # returns {el: wt fraction}
 
         return TOT
 

tests/test_solution.py

@@ -392,7 +392,7 @@ def test_components_by_element(s1, s2):
 
 
 def test_get_total_amount(s2):
-    assert np.isclose(s2.get_total_amount("Na(1)", "mol").magnitude, 8)
+    assert np.isclose(s2.get_total_amount("Na(1)", "g").magnitude, 8 * 58, 44)
     assert np.isclose(s2.get_total_amount("Na", "mol").magnitude, 8)
     sox = Solution({"Fe+2": "10 mM", "Fe+3": "40 mM", "Cl-": "50 mM"}, pH=3)
     assert np.isclose(sox.get_total_amount("Fe(2)", "mol/L").magnitude, 0.01)