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Diamond is forever" is one of the most successful advertising slogans of all time. but is it true? for the reaction shown below,

Zielflug [23.3K]

The given reaction is

$C _{(Diamond)}\rightarrow C_{(Graphite)}$

An element can exist in 2 or more different forms which have totally different chemical and physical properties. They are known an allotropes.

Diamond and Graphite are allotropic forms of carbon. In the given reaction, diamond is changing to graphite and we have to find out the standard free energy of this reaction. This will help us to find out whether this reaction is spontaneous at 298 K or not.

The following data is needed for calculations which is taken from standard reference table.

$H_{f}^{0}(diamond)= 1.895 kJ/mol$

$H_{f}^{0}(graphite)= 0$

$S^{0}(diamond)=2.337 J/mol-K$

$S^{0}(graphite)=5.740 J/mol-K$

Step 1: Find ΔH⁰ rxn for the given reaction.

The formula to calculate ΔH⁰ rxn is given below.

$\bigtriangleup H^{0}_{rxn}= H_{f}(product)- H_{f}( reactant)$

We have graphite on product side and diamond on reactant side.

Therefore, $\bigtriangleup H^{0}_{rxn}= H_{f}(graphite)- H_{f}(diamond)$

Let us plug in the values given above.

$\bigtriangleup H^{0}_{rxn}= 0 - 1.895 kJ/mol$

$\bigtriangleup H^{0}_{rxn}= - 1.895 kJ/mol$

ΔH⁰ rxn for the given reaction is -1.895 kJ/mol

Step 2 : Find ΔS⁰ rxn for the given reaction.

The formula to calculate ΔS⁰ rxn is

$\bigtriangleup S^{0}_{rxn}= S^{0}(product)- S^{0}( reactant)$

$\bigtriangleup S^{0}_{rxn}= S^{0}(graphite)- S^{0}(diamond)$

$\bigtriangleup S^{0}_{rxn}= (5.740J/mol.K) - (2.337 J/mol.K)$

$\bigtriangleup S^{0}_{rxn}= 3.403 J/mol.K$

Let us convert this to kJ.

$\frac{3.403J}{mol.K}\times \frac{1 kJ}{1000J}= 3.403\times 10^{-3}kJ/mol.K$

ΔS⁰ rxn for the given reaction is 3.403 x 10⁻³ kJ/mol.K

Step 3: Find standard free energy ΔG⁰ rxn.

ΔG⁰ rxn for the given reaction is calculated as

$\bigtriangleup G^{0}_{rxn}= \bigtriangleup H^{0}_{rxn}- T\times \bigtriangleup S^{0}_{rxn}$

We have T = 298 K. Let us plug in the calculated values of ΔH⁰ rxn and ΔS⁰ rxn.

$\bigtriangleup G^{0}_{rxn}= - 1.895 kJ/mol - [(298K)\times 3.403\times 10^{-3}kJ/mol.K]$

$\bigtriangleup G^{0}_{rxn}= - 1.895 kJ/mol - [1.014 kJ/mol]$

$\bigtriangleup G^{0}_{rxn}= - 2.909 kJ/mol$

The standard free energy change for the given reaction is -2.909 kJ/mol

The negative value of delta G⁰ suggests that the given reaction is spontaneous at room temperature. That means diamond will slowly convert to graphite. The speed of this reaction is extremely slow, but yet the reaction is taking place. So over a period of time diamond will become graphite.

Therefore "Diamond is forever" is not true as it is going to get converted to graphite.

7 0

3 years ago

Magnesium carbonate, MgCO3, reacts with nitric acid, HNO3, to form magnesium nitrate and carbonic acid. Carbonic acid reacts to

Karolina [17]

Carbonic acid undergoes decomposition reaction. Decomposition reaction starts with one reactant and forms two or more products: AB⇒A+B. In this reaction, H2CO3 ⇒H2O + CO2.

8 0

2 years ago

The molarity (M) of an aqueous solution containing 29.8 g of sucrose, C12H22O11, in 120 mL of solution is:

Rama09 [41]

Answer:

0.726 mol·L⁻¹

Step-by-step explanation:

c = moles/litres

=====

Moles = 29.8 × 1/342.30

Moles = 0.087 06 mol

=====

Litres = 120 × 1/1000

Litres = 0.120 L

=====

c = 0.087 06/0.120

c = 0.725 mol·L⁻¹

5 0

3 years ago

What is the<br> mass of 1.82<br> moles of<br> Lithium<br> carbonate?

frutty [35]

Answer:

244.76

Explanation:

The weight of grams by 1.82 moles of lithium carbonate would be: 134.481438 So we need to use this equation to find mass by grams m × g = ms Where m is for moles, g for grams, and ms for mass. So now we need use this equation: 1.82 × 134.481438 = ? 1.82 × 134.481438 = 244.75621716 244.75621716, rounded-up (to the nearest-tenths place) is 244.76. So now you have it! The mass of 1.82 moles of lithium carbonate is 244.76!

7 0

2 years ago

Who controlled the distribution of agricultural products within a Mississippian community?

Sunny_sXe [5.5K]

Answer:

The chiefs

Explanation:

hope my answers is helpful

5 0

1 year ago

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