1. Thermochemical equation is balance stoichiometric chemical equation written with the phases of the reactants and products in the brackets along with the enthalpy change of the reaction.

The given correct thermochemical reactions are:

$Fe(s)+O_2(g)\rightarrow Fe_2O_3(s),\Delta H = 3,926 kJ
$

$C_3H_8(g)+5O_2 (g)\rightarrow 3CO_2 (g)+4H_2O(l),\Delta H= 2,220 kJ/mol$

2. Phase change affect the value of the enthalpy change of the thermochemical equation. This is because change in phase is accompanied by change in energy. For example:

$H_2O(s)\rightarrow H_2O(g),\Delta H_{s}=51.1 kJ/mol$

$H_2O(l)\rightarrow H_2O(g),\Delta H_{v}=40.65 kJ/mol$

In both reaction phase of water is changing with change in energy of enthalpy of reaction.

7 0

3 years ago

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Give explanations for the large drops in melting point from C to Si and from Ge to Sn.

____ [38]

As we move down the group, the metallic bond becomes more stable and the formation of forming covalent bond decreases down the group due to the large size of elements.

Covalent and metallic bonding leads to higher melting points. Due to a decrease in attractive forces from carbon to lead there is a drop in melting point.

Carbon forms large covalent molecules than silicon and hence has a higher melting point than silicon.

Similarly, Ge also forms a large number of covalent bonds and has a smaller size as compared to that of Sn. Hence melting point decreases from Ge to Sn.

The order will be C>Si>Ge>Pb>Sn.

To learn more about the covalent bond, visit: brainly.com/question/10777799

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3 0

2 years ago

Is O2 covalent molecular or polar covalent

Dimas [21]

Yes it yes molusbus ks jshs jsbjsus js js sjs js sj dis dis jsys snsus

6 0

3 years ago

Open the Balancing Chemical Equations interactive and select Introduction mode. Then choose Separate Water. Adjust the coefficie

aleksklad [387]

Explanation:

1. Water decomposition

Decomposition reactions are represented by-

The general equation: AB → A + B.

Various methods used in the decomposition of water are -

Electrolysis
Photoelectrochemical water splitting
Thermal decomposition of water
Photocatalytic water splitting

Water decomposition is the chemical reaction in which water is broken down giving oxygen and hydrogen.

The chemical equation will be -

$H_2O + H_2 + O_2$

Hence, balancing the equation we need to add a coefficient of 2 in front of $H_2O$ on right-hand-side of the equation and 2 in front of $H_2$ on left-hand-side of the equation.