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  2. Amount of substance - Wikipedia

    en.wikipedia.org/wiki/Amount_of_substance

    In chemistry, the amount of substance (symbol n) in a given sample of matter is defined as a ratio (n = N/N A) between the number of elementary entities (N) and the Avogadro constant (N A). Since 2019, the value of the Avogadro constant N A is defined to be exactly 6.022 140 76 × 10 23 mol −1 .

  3. Sodium acetate - Wikipedia

    en.wikipedia.org/wiki/Sodium_acetate

    C 2 H 3 Na O 2: Molar mass: 82.034 g·mol −1 : Appearance White deliquescent powder or crystals Odor: Vinegar (acetic acid) odor when heated to decomposition [1]: Density: 1.528 g/cm 3 (20 °C, anhydrous)

  4. Atomicity (chemistry) - Wikipedia

    en.wikipedia.org/wiki/Atomicity_(chemistry)

    Atomicity is the total number of atoms present in a molecule of an element. For example, each molecule of oxygen (O 2) is composed of two oxygen atoms. Therefore, the atomicity of oxygen is 2. [1] In older contexts, atomicity is sometimes equivalent to valency. Some authors also use the term to refer to the maximum number of valencies observed ...

  5. Sodium carbonate - Wikipedia

    en.wikipedia.org/wiki/Sodium_carbonate

    Sodium carbonate decahydrate (Na 2 CO 3 ·10H 2 O), also known as washing soda, is the most common hydrate of sodium carbonate containing 10 molecules of water of crystallization. Soda ash is dissolved in water and crystallized to get washing soda. Na 2 CO 3 + 10 H 2 O → Na 2 CO 3 ·10H 2 O. It is one of the few metal carbonates that is ...

  6. Stoichiometry - Wikipedia

    en.wikipedia.org/wiki/Stoichiometry

    By definition, the atomic mass of carbon-12 is 12 Da, giving a molar mass of 12 g/mol. The number of molecules per mole in a substance is given by the Avogadro constant, exactly 6.022 140 76 × 10 23 mol −1 since the 2019 revision of the SI. Thus, to calculate the stoichiometry by mass, the number of molecules required for each reactant is ...

  7. Avogadro constant - Wikipedia

    en.wikipedia.org/wiki/Avogadro_constant

    The Avogadro constant, commonly denoted N A [1] or L, [2] is an SI defining constant with an exact value of 6.022 140 76 × 10 23 mol −1 (reciprocal moles). [3] [4] It defines the number of constituent particles in one mole, where the particles in question can be either molecules, atoms, ions, ion pairs, or any other elementary entities.

  8. Law of multiple proportions - Wikipedia

    en.wikipedia.org/wiki/Law_of_multiple_proportions

    For example, if one tried to demonstrate it using the hydrocarbons decane (C 10 H 22) and undecane (C 11 H 24), one would find that 100 grams of carbon could react with 18.46 grams of hydrogen to produce decane or with 18.31 grams of hydrogen to produce undecane, for a ratio of hydrogen masses of 121:120, which is hardly a ratio of "small ...

  9. Reaction rate constant - Wikipedia

    en.wikipedia.org/wiki/Reaction_rate_constant

    where A and B are reactants C is a product a, b, and c are stoichiometric coefficients,. the reaction rate is often found to have the form: = [] [] Here ⁠ ⁠ is the reaction rate constant that depends on temperature, and [A] and [B] are the molar concentrations of substances A and B in moles per unit volume of solution, assuming the reaction is taking place throughout the volume of the ...