# Questions tagged [chemical-formula]

For questions related to molecular formula, empirical formula, formula unit, representing the chemical proportions of atoms that constitute a particular chemical compound, molecule, ion, complex, crystal, etc. using chemical element symbols, numbers, and other symbols. NOT related to 'notation', 'composition', 'structure' or 'nomenclature'.

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### What does fractional notation represent in molecular formulas such as SiO4/2 or H2SiO2/2?

I'm going through some papers about HSQ (hydrogen silsesquioxane) and keep seeing this fractional notation being used: HSiO3/2 , SiO4/2 , H2SiO2/2 , H3SiO1/2. Example paper. I understand that the ...
1 vote
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### How to get the total number of numbered positions in a molecule/compound

I'm working on a metabolite database where "labeled" compounds can contain isotopically labeled atoms in specific positions. When a new labeled compound is entered into the database, we'd ...
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1 vote
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### Determining the number of triphenylphosphine ligands in nickel(II) complex

A complex is synthesised by combining hydrated solutions of $\ce{NiCl2}$ $(\pu{0.6 g})$ with $\pu{1.35 g}$ triphenylphosphine $(\ce{PPh3}).$ After cooling the product precipitates as a solid with ...
1 vote
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### What is the materials science behind thermal diffusion in multispectral camouflage?

I've been interested in infrared and near-infrared camouflage (called multispectral camouflage) for a couple of days now, and I've found a video or two of certain companies that have created fabrics ...
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### How do I calculate the empirical formula when ash is present in the percentage composition?

I am trying to calculate a chemical formula. How do I calculate the empirical formula when ash is present in the percentage composition? Example- C- 47.7% H- 7.2% N- 1.8% S- 0.9% O- 38.0% Ash- 4.4% ...
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### How can the multiplicative number (n) of a chemical series like polyethylene glycol (PEG) be a non-integer?

https://en.m.wikipedia.org/wiki/PEG_400 Down at chemical or molecular formula, it says: C_2n H_4n+2 O_n+1, like for all polyethylene glycols (PEG)s, but then says n=8.2 to 9.1.... Huh?
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### Chemical reaction of bronze tarnishing

Can anyone explain to me the chemical process of bronze tarnishing? According to Wikipedia: Bronzes are typically ductile alloys, considerably less brittle than cast iron. Typically bronze oxidizes ...
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### What's the effect of Pressure change in Chemical Equilibrium if any reactant or product is Solid or Liquid?

I am studying La-Chatelier's Principle of Chemical Equilibrium. I got a problem of Pressure change in Chemical Equilibrium. I know that Pressure change If a reversible reaction is in equilibrium ...