General Chemistry is an iOS application, that is available in Apple Store. It provides user with the most essential chemical data and calculators, such as interactive periodic table, chemical elements info, chemical reaction balancer, pH, ideal gas, Molecular Weight and mass composition calculators.
The applications presents periodic table of chemical elements, that coloured with respect to the category they belong to. (Metals, Halogens, etc..)
Element Categories: Diatomic Nonmetals, Noble Gases, Alkali Metals, Alkaline Earth Metals, Metalloids , Transition Metals, Post-Transition Metals, Polyatomic Nonmetals, Lanthanides, Actinides (Elements can be grouped differently, based on source).
Each element can be selected and then pressing the “Element” bar button leads to detailed info page:
Additionally the app provides calculators, that target the most common chemical tasks:
- Balancing chemical reaction equations.
- Estimation of pH of strong and weak, monoprotic or polyprotic acid or base solutions.
- Ideal gas (pV=nRT) calculator with units conversions.
- Molecular weight and mass fraction analysis.
Following example calculates pH of H2SO4 acid, that has strong first deprotonation step (empty Ka1 field) and Ka2 = 1.2e-2 and Ka3 field is automatically inactivated:
Following example calculates pH of Strong Base (NaOH) ( Kb fields are automaticaly inactivated):
Important notes:
Reaction Balancer and Molecular Analysis:
Molecular formula format: charge, if exists, must be provided as well, separated by coma: Na,+ ; SO4,2- . Application supports state indexes: (g), (s), (l), (aq) – all are lowercase only, placed at the end of the compound formula. Valid examples: Mg(HCO3)2, CaCl2.2H2O, CaCl2*2H2O, (NH4)2Fe(SO4)2.6H2O, Mg(H2PO4)2, C6H12O6, Na, 2+(aq). Analyser is case sensitive.
For stoichiometric analysis of chemical reaction please refer to “Stoichiometry”.
pH Calculator:
Tapping the first field (Acid Strong 1P) will select the type of the analysed acid or base.
Acid Strong 1P – Acid monoprotic, that completely dissociates to electrolytes.
Acid Weak 1P – Acid monoprotic, which dissociation is dictated by equilibrium constant Ka1.
Acid Weak 2P -Acid biprotic, which dissociates by two stages defined by equilibrium constant Ka1 and Ka2.
Base Weak 3P -Base triprotic, which dissociates by three stages defined by equilibrium constant Kb1, Kb2 and Kb3.
Estimation of solution pH values is based on advanced quantitative chemical analysis which allows simultaneous calculation of all dissociation stages of acids and bases and water dissociation (Kw).
The dissociation constants fields accept both formats: 1) pK values (-log(K)) and 2) regular K values, but only in a particular scientific format, which requires inclusion of exponential part “e” (for example: 1e-5 instead of 0.00001, or 2.5e0 instead of 2.5). Empty dissociation constant field would imply that this dissociation step is “strong” or complete.
For acid – base titration and indicators please refer to “Acid Base pH”.
Ideal Gas calculator:
Fill data for all variables, except the one that must be calculated. User can choose the most convenient units for input and output variables before calculation, so the output value will be adjusted for the required units. Touching the units field scrools through the available units.
More sofisticated equations with extended list of units can be calculated by means of Formula & Units application.
Roman Volinsky, Ph.D. 
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