1. G

    The number of atoms in an amount of a substance

    According to Wikipedia, its (quoting) the number of discrete atomic-scale particles in it divided by the Avogadro constant So a molecule of hydrogen would have an amount of substance of 2/NA and would have a mass of 2/(6*10^23) daltons?
  2. M

    B Why Use Nuclear Charge In Finding Energy Value of Singular Electron?

    My Textbook says this is the formula to find energy values for electron shells: $$E_{mol of electrons} = \frac{-1312kJ}{n^2}$$ where $n$ is in electron shell number But when we divide by 1 mol to get the energy value for each electron we get $$E_{electron} = \frac{-2.178 \cdot 10^{-18}}{n^2}...
  3. P

    How to calculate weight needed for a concentration

    I haven't had a chemistry class in many years. Recently I saw an interesting article that used a solution of resveratrol (228.25 grams per mole) in dimethylsulfoxide (78.13 grams per mole). The concentration was listed as 5 uMol. If I had 10 grams of DMSO how much resveratrol would I add to...
  4. T

    Trouble finding where I went wrong calculating concentration

    In our laboratory class we were required to calculate the stock (mM) and final (µM) concentrations for Glycerol. The tutor said my final calculations were incorrect and that I had made an error. He didn't have enough time show me where I went wrong. I have compared my results with another...
  5. donaldparida

    Fundamental problem regarding mole concept

    Background: Amount of substance is a fundamental physical quantity which has mole (mol) as it's SI unit. Therefore all expressions for amount of substance should have the unit mole on simplification. Therefore, if A = Amount of substance (normally in moles), m = Mass of the substance in a...
  6. Wrichik Basu

    A problem in volumetric calculations in Chemistry

    Homework Statement :[/B] The density of a 2.05 molar solution of acetic acid is 1.02g/ml. The Molality of the solution is: (a) 1.14 mole/kg (b) 3.28 mole/kg (c) 2.28 mole/g (d) 0.44 mole/kg Homework Equations :[/B] The Attempt at a Solution :[/B] I tried it out very simply using unitary...
  7. Priyadarshini

    Chemistry Mole Sum

    Homework Statement The reaction between aluminium powder and anhydrous barium nitrate is used as the propellant in some fireworks. The metal oxides and nitrogen are the only products. Which volume of nitrogen, measured under room conditions, is produced when 0.783 g of anhydrous barium nitrate...