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son4ous [18]
3 years ago
6

A scientist measures the standard enthalpy change for the following reaction to be 67.9 kJ:

Chemistry
1 answer:
bekas [8.4K]3 years ago
3 0

Answer: The standard enthalpy of formation  of H_2O(g) is  -252.1 kJ/mol.

Explanation:

The balanced chemical reaction is,

Fe_2O_3(s)+3H_2(g)\rightarrow 2Fe(s)+3H_2O(g)

The expression for enthalpy change is,

\Delta H=[n\times H_f_{products}]-[n\times H_f_{reactantss}]

Putting the values we get :

\Delta H=[2\times H_f{Fe}+3\times H_f{H_2O}]-[1\times H_f{Fe_2O_3}+3\times H_f{H_2}]

67.9kJ=[(2\times 0)+(3\times H_f{H_2O})]-[(1\times -824.2kJ/mol)+3\times 0kJ/mol)]

H_f{H_2O}=-252.1kJ/mol

Thus standard enthalpy of formation  of H_2O(g) is  -252.1 kJ/mol.

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Answer:

<u>One lone-Pair is present in Ammonia</u>

<u></u>

Explanation:

The number of valence electron in N = 5

The number of Valence electron in H = 1

The formula of ammonia = NH3

Total valence electron in ammonia molecule = 5 +3(1) = 5+3 = 8

The lewis structure suggest that :

Nitrogen completes its octet by sharing the electron pair with 3 hydrogen atoms.

3 electron of Nitrogen are involved in sharing with Hydrogen

So,<u><em> remaining two electron are left non-bonded</em></u> . Hence they exist as lone- pair

So, there is only 1 lone pair in the ammonia molecule .

The shape of NH3 is bent according to VSEPR theory . This is so because the presence of 1 lone pair causes more repulsion and occupy more space.

Thus the lone pair is changing the shape of the ammonia molecule . It also increase the dipole moment of the molecule , which gives polarity to it.

5 0
3 years ago
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Marianna [84]
I believe the answer is 3 - He hypothesized that all substances can be broken down into a smallest part called the atom. 
7 0
3 years ago
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Calculate the standard potential for the following galvanic cell: Ni(s) | Ni2+(aq) || Ag+(aq) | Ag(s) which has the overall bala
mylen [45]

Answer:

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Explanation:

The standard reduction potentials are:

Ag^+/Ag     E° =  0.7996 V  

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The half-cell and cell reactions for Ni | Ni^2+ || Ag^+ | Ag are

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<u>2Ag^+ 2e- → 2Ag               </u>    <u>E° = 0.7996 V </u>

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To three significant figures, the standard potential for the cell is 1.06 V .

8 0
3 years ago
Your future is affected by your choices today? I agree or disagree​
just olya [345]

Answer:

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Explanation:

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3 years ago
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VikaD [51]
<h3>In reference to the diagram attached </h3><h3>Answer:</h3>

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8 0
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