Calculate : Stoichiometry

Oleh

 
Understanding: Stoichiometry
Stoichiometry comes from the Greek word stoicheion means element and metrain means to measure. Stoichiometry can be defined as follows:
1. Calculation chemical concerns relationship quantitative substances involved in reactions, either reactor As well Results reaction.
2. Stoichiometry is branch science chemical study relationship quantitative from composition Substances chemistry and reaction.
The basic laws of chemistry are:
1. Law eternity mass
2. Law comparison permanent
3. Dalton's law or law comparison Multiple
4. Gay-Lussac Law or law Volume comparison
5. Avogadro's law
 
Understanding Concepts: Stoichiometry 

Relative atomic mass (Ar) and mass molecule relative (Mr)
The relative atomic mass (Ar) is the mass ratio of an atom of an element with a comparable atom. While the relative molecular mass (Mr) equals the molecular weight (BM). Formula : 

Keterangan :
C12  = 1,993 x 10-23 gram

Concept Mol and Equation Reaction
One mole is the number of substances containing a number of simple units equal to the avogandro number. One mole of the equivalent of 6:02 x 10 23 particles. To recall the relationship between the concept of mole and the number of particles, atomic / molecular mass, standard volume, and molarity, consider the following "Bridge Mol" diagram!
Gambar 1.1
Equation Reaction
A right reaction if it meets:
• The law of mass conservation
• The law of conservation of charge
To meet both laws, the reaction coefficient must be equalized. In a reaction, the reaction coefficient states: The mole ratio or for the gas phase also expresses the volume ratio.

Gambar 1.2
Chemical equations use symbols and formulas for elements or compounds involved in the reaction. A chemical equation describes the reaction, shown by arrows, from reactants to products. The stoichiometric coefficients are placed before symbols or formulas in equations to balance equations. As required by the law of conservation of mass, each element equals both on the product side and on the side of the reactant. 
 
Formula Empirical and Formula Molecule
Empirical Formula: the formula which states the smallest comparison of atoms of the elements that make up a compound. For example, H 2 O and CH 2 O
Molecular formula: a formula which expresses the number of atoms of the elements that make up a senyawa.Contoh molecule, H 2 O and C 6 H 12 O 6
 
Example Calculation: Stoichiomentry
  1. Define mass molecule relatively compound H 2 CO 3, if is known relative atomic mass (Ar): H = 1, C = 12, O = 16.
Solution:
Mr H 2 CO 3 = (2 x Ar H) + (1 x Ar C) + (3 x Ar O).
= (2 x 1) + (1 x 12) + (3 x 16)
= 2 + 12 + 48
= 62.
  1. Given reaction as following
    H 2 S + O 2     → S + H 2 O

    If the above reaction produce 320 grams of sulfur, specify the volume of H 2 S required at STP
    (Ar S = 32; H = 1)

    Discussion
    Mol sulfur formed is
    mol = gram / Ar
    = 320/32
    = 10 mol

    Mol H 2 S required = 10 mol also (Due coefficient H 2 same with coefficients S)

    So that the volume of H 2 S in STP
    V = mol x 22.4 liters
    = 10 x 22.4 = 224 liters
  1. Given reaction metal aluminum and solution acid Chloride as following

    If mass metal aluminum reacts 8, 1 gram specify the volume of H 2 gas formed on Circumstances standard!
    (Ar Al = 27; H = 1; Cl = 35.5)
Discussion
The reacting aluminum metal mol is

Mol H 2 is formed

Volume H 2 formed in the default state is
V = n × 22.4 liters
V = 0.45 × 22.4 liter = 10.08 liters
  1. Given reaction as following:
    2H 2 (g) + 2NO (g)     → 2H 2 O + N 2 (g)

    If 0.8 mol of H 2 Out react, specify
    a) Amount NO reacts mole
    b) Amount mol H 2 O generated
    c) Amount mol of N 2 produced

    Discussion
    a) Amount NO reacts mole
    = 2/2 x moles of H 2
    = 2/2 x 0.8
    = 0.8 mol

    b) Amount mol H 2 O generated
    = 2/2 x moles of H 2
    = 2/2 x 0.8
    = 0.8 mol

    c) Amount mol of N 2 produced

    = 1/2 x moles of H 2
    = 1/2 x 0.8
    = 0.4 mol

Komentar

  1. FERONIKA6 Mei 2017 pukul 18.31

    What is a limiting reaction? Give example

    BalasHapus
    Balasan
    1. Unknown9 Mei 2017 pukul 05.34

      Limiting reagent is a reactant contained in the relatively smallest amount (in the stoichiometric relationship). The limiting reagents will run out, while the other reactions will leave the rest.
      Example:
      One mole of sodium hydroxide solution (NaOH) is reacted with 1 mole of sulfuric acid (H 2 SO 4) solution according to the reaction
      2 NaOH (aq) + H2SO4 (aq) -> Na2SO4 (aq) + 2 H2O (l)
      Resolution:
      The mol of each substance is divided coefficient, then select a small divide as a limiting reagent
      - mole NaOH / NaOH coefficient
      = 1/2 mol
      = 0.5 mol
      - mol H2SO4 / H2SO4 coefficient
      = 1/1 mol
      = 1 mol
      Since the yield is NaOH Na2SO4 (aq) + 2 H2O (l)

      First: 1 mol 1 mol 0 0

      Reacts: (2x0.5) = 1 mol (1x0.5) = 0.5 mol

      Residual: 1-1 = 0 moles 1-0,5 = 0.5 mole 0.5 mole 1 mole

      The remaining reagent is H2SO4

      Hapus
  2. Mutia11 Mei 2017 pukul 03.21

    What ara the differences between formula empirical and formula molecule?

    BalasHapus
    Balasan
    1. Unknown11 Mei 2017 pukul 16.00

      The difference, if the molecular formula is a formula that states the number of atoms of the elements that make up one molecule of a compound. While the empirical formula is the formula that states about the smallest comparison of atoms of the elements that make up a chemical compound.

      Hapus
  3. Unknown13 Mei 2017 pukul 17.49

    Can you explain about stoichiometry is a subject in chemistry that studies the quantity of matter in a chemical reaction?

    BalasHapus
    Balasan
    1. Unknown14 Mei 2017 pukul 03.56

      Yes, I can.
      Actually stoichiometry learns about the chemical calculations related to the number of moles, the number of molecules, the amount of volume, the number of kemolaran and many more chemical calculations that are related to elements, compounds in a chemical reaction.

      Hapus

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