Standard Enthalpies of Formation at 25 C Part A Write an equation for the format

Question

Standard Enthalpies of Formation at 25 C

Part A

Write an equation for the formation of HCl(g) from its elements in their standard states.

Express your answer as a chemical equation. Identify all of the phases in your answer.

Part C

Write an equation for the formation of MgO(s) from its elements in their standard states.

Express your answer as a chemical equation. Identify all of the phases in your answer.

Part E

Write an equation for the formation of FeCl3(s) from its elements in their standard states.

Express your answer as a chemical equation. Identify all of the phases in your answer.

Part G

Write an equation for the formation of CH4(g) from its elements in their standard states.

Express your answer as a chemical equation. Identify all of the phases in your answer.

Substance Hf(kJ/mol) C(s,graphite) 0 C(s,diamond) 1.88 C(g) 716.7 CH4(g) 74.6 C2H4(g) 52.4 Mg(s) 0 Mg(g) 147.1 MgO(s) 601.6 Cl(g) 121.3 Cl2(g) 0 Cl(aq) 167.1 H(g) 218.0 H2(g) 0 Fe(s) 0 Fe(g) 416.3 FeCl3(s) 399.5 FeCl2(s) 341.8 N(g) 472.7 N2(g) 0 HCl(g) 92.3 HCl(aq) 167.2 O(g) 249.2 O2(g) 0 O3(g) 142.7

Explanation / Answer

A)

consider HCl

here the elements are hydrogen and chloride

we know that

the standard heat of formation of elements in their standard state is zero

from the table we can see that

the standard state of hydrogen is H2 (g)

the standard state of chlorine is Cl2 (g)

so

the equation for the formation of HCl (g) is

(1/2) H2 (g) + (1/2) Cl2 (g) ----> HCl (g)

C)

consider MgO (s)

here the elements are magnesium and oxygen

from the table we can see that

the standard state of Magnesium is Mg (s)

the standard state of oxygnen is O (g)

so

the equation for the formation of MgO (s) is

Mg (s) + (1/2) 02 (g) ---> MgO (s)

E)

now consider FeCl3 (s)

here the elements are iron and chlorine

from the table we can see that

standard state of iron is Fe (s)

standard state of chlorine is Cl2 (g)

so

the equation for the formation of FeCl3 is

Fe (s) + (3/2) Cl2 (g) ----> FeCl3 (s)

G)

consider CH4 (g)

here the elements are Carbon and Hydrogen

from the table

we can see that

standard state of carbon is C (s , graphite)

standard state of Hydrogen is H2 (g)

so

the equation for the formation of CH4 is given by

C (s, graphite) + 2 H2 (g) ---> CH4 (g)

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