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3 years ago

Why isn't hess's law helpful for calculating the heat of reaction involved in the conversion of diamond to graphite?

2 answers:

7 0

Hess' Law of Constant Heat Summation was developed by Germain Henri Hess who lived from 1802 - 1850. This law became important primarily for his thermochemical studies. This law states that the heat released or absorbed in the chemical reaction is unchanged or the same irregardless of how many steps the reactants take in order to convert to products.

This law is not applicable or not helpful in the conversion of diamond to graphite because both are just allotropes of carbon along with C60 (Buckminsterfullerene or buckyball), C540, C70, amorphous carbon, and carbon nanotube.

IceJOKER [234]3 years ago

3 0

Hess's law is applicable when the reactants are different than the products. In a chemical reaction there are rearrangement of atoms such that the chemical property of the reactant is different than that of the product.

Diamond and graphite are purely made up of C atoms with different arrangements of C atoms thus making them allotropes. Hess's law is not applicable for allotropes.

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. Metallic iron has a body-centered cubic lattice with all atoms at lattice points and a unit cell whose edge length is 286.6 pm

adell [148]

Answer:

$\large \boxed{\text{55.8 u}}$

Explanation:

1. Calculate the volume of the unit cell

V = l³ = (2.866 × 10⁻⁸ cm)³ = 2.354 × 10⁻²³ cm³

2. Calculate the mass of a unit cell

$\text{Mass} = 2.866 \times 10^{-23}\text{ cm}^{3} \times \dfrac{\text{7.87 g}}{\text{1 cm}^{3}} = 1.853 \times 10^{-22} \text{ g}$

3. Calculate the mass of one atom

A body-centred unit cell contains two atoms.

$\text{Mass of 1 atom} = \dfrac{1.853 \times 10^{-22} \text{ g}}{\text{2 atoms}} \times \dfrac{\text{1 u}}{1.661 \times 10^{-24}\text{ g}} = \textbf{55.8 u}\\\\\text{The molar mass of Fe from the Periodic Table is $\large \boxed{\textbf{55.845 g/mol}}$}$

6 0

3 years ago

Why is the electrical charge of an atom zero or neutral?

kompoz [17]

Because the atom isn't a isotope. The electrons, (negative charge) , and the protons, (positive charge), balance each other out.

8 0

3 years ago

Read the information about the halogen family.

Elodia [21]

Answer:

See explanation

Explanation:

Chlorine is a member of the halogen family known as a toxic yellowish green gas. Inhalation of chlorine for a prolonged period of time leads to pulmonary edema. If a person comes in contact with compressed liquid chlorine the person may experience frostbite of the skin and eyes.

However chlorine is very useful in water disinfection and is preferred in water treatment because it provides residual disinfection of the treated water.

Chlorine gas may be dissolved in NaOH to form oxochlorate I which is used as a bleach in cleaning.

7 0

3 years ago

When you are converting grams to moles , are you multiplying or dividing ?

Effectus [21]

When you are converting grams to moles, the operation that you will be doing is dividing by the molar mass to obtain the amount of moles of the given sample.

4 0

3 years ago

Kryger [21]

The empirical formula : C₁₂H₄F₇

The molecular formula : C₂₄H₈F₁₄

<h3>Further explanation</h3>

mol C (MW=12 g/mol)

$\tt \dfrac{18.24}{12}=1.52$

mol H(MW=1 g/mol) :

$\tt \dfrac{0.51}{1}=0.51$

mol F(MW=19 g/mol)

$\tt \dfrac{16.91}{19}=0.89$

mol ratio of C : H : O =1.52 : 0.51 : 0.89=3 : 1 : 1.75=12 : 4 : 7

Empirical formula : C₁₂H₄F₇

(Empirical formula)n=molecular formula

( C₁₂H₄F₇)n=562 g/mol

(12.12+4.1+7.19)n=562

(281)n=562⇒ n =2

Molecular formula : C₂₄H₈F₁₄

6 0

3 years ago