Which one of the following is a correct formation reaction?

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Which one of the following is a correct formation reaction?


C(diamond) → C(graphite)

H2(g) + O(g) → H2O(l)

C(graphite) + 4H(g) → CH4(g)

6C(graphite) + 6H2O(s) → C6H12O6(s)

2C(graphite) + 3H2(g) + ½O2(g) → C2H5OH(l)

I said C(diamond)–>C(graphite). What do you think?

5 Answers

  • a ‘correct’ formation reaction would show the individual elements combining to form 1 mole of product

    and would be balanced accordingly

    C(diamond) → C(graphite)

    — No – this is a physical change, not chemical

    H2(g) + O(g) → H2O(l)

    —No – H2(g) + 1/2 O2(g) → H2O(l) would be correct

    C(graphite) + 4H(g) → CH4(g)

    —No – C(graphite) + 2 H2(g) → CH4(g) would be correct

    6C(graphite) + 6H2O(s) → C6H12O6(s)

    —No – 6C(graphite) + 6H2(g) + 3O2(s) → C6H12O6(s) would be correct

    2C(graphite) + 3H2(g) + ½O2(g) → C2H5OH(l)

    —YES – this is correct for the formation of one mole of ethanol from its elements

  • C(diamond) → C(graphite) Graphite is the standard state, so this would be written as C(graphite) → C(diamond)

    H2(g) + O(g) → H2O(l) THis has the problem that Oxygen usually exist as as O2, and under conditions which woulds split O2 into O [extreme temperatures] H2 would also split, and H2O would not form. H2 + 1/2 O2 would be OK

    C(graphite) + 4H(g) → CH4(g) Same basic problem; while you could react graphite with atomic [really really hot] hydrogen, CH4 would not form; hot enough to smash H2 to H would also smash CH4 THe reaction C + 2 H2 would be OK

    6C(graphite) + 6H2O(s) → C6H12O6(s) This could happen; however, the reaction is going to proceed extremely slowly at ice temperatures…. Like it’ll take a few billion years or longer. However, for finding a heat of formation you would use water in the liquid phase. So toss this one too.

    2C(graphite) + 3H2(g) + ½O2(g) → C2H5OH(l) This could happen; the reaction as written is OK. Especially as a heat of formation reaction.

  • In point of fact the stable form of carbon is graphite so it is graphite that has zero delta H f.

    The bonding is graphite is stronger due to delocalisation – the fact that it is physically weaker is confusing.

    You correctly avoided 2,3 (atoms are not standard state) and 4 (from elements) so that leaves

    2C(graphite) + 3H2(g) + ½O2(g) → C2H5OH(l)

    Presumably you though that graphite as not the standard state.

  • you need to understand the question clearly. chemical Reaction is either combination,or dissociation ,or displacement of atoms or group of atoms.change in allotropic form is also a reaction.the given equations of H2 and O

    graphite and H,graphite and water,graphite an hydrogen and oxygen though theoretically correct are improbable as conditions are not given.The conversion of diamond to graphite is the only answer which can be called correct.

  • Diamond, graphite and soot are all made of carbon atoms.

    The chemical formula of diamond is C which is the chemical symbol for the element carbon. Soot and graphite are also made up of carbon atoms and have the same chemical symbol, C. So what’s the difference between soot, graphite and diamond if they are all made up of the same carbon atoms?

    Carbon atoms can be arranged in many different physical forms called allotropes.

    An allotrope is a form of an element that has different physical properties (eg. colour, crystal shape, hardness, melting points, boiling points, etc.) due to different arrangements of atoms or molecules within the structure.

    Four allotropes of carbon are diamond, buckminsterfullerene (bucky balls), graphite and soot. Since all are forms of the element carbon, they each have the same chemical symbol C.

    The allotropes of carbon however, differ greatly in their structure and properties.

    In diamond the carbon atoms are covalently bonded to one another producing a three dimensional network solid. Each carbon atom is bonded to four other atoms throughout the crystal lattice.

    Diamond has no free electrons because they are all involved in bonding and is therefore a poor conductor of electricity.

    Graphite is also made of carbon atoms. Graphite consists of carbon atoms covalently bonded together in a layers made up of hexagons, like cнιcκen wire.

    Each carbon atom has three bonds and one free electron. The extra electrons are delocalised and can be moved along the layers by applying an external voltage.This is why graphite can conduct an electric current.

    Graphite unlike diamond is extremeley soft. Between the parallel layers of graphite are weak intermolecular bonds,

    But, your presumption C–> C is correct.

    Source(s): www.chemicalformula.org

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