C, h, o, n, p and s make up > 90% of all organic compounds. t or f?

Anna [14]

Considering the Hess's Law, the enthalpy change for the reaction is 221.8 kJ/mol.

Hess's Law indicates that the enthalpy change in a chemical reaction will be the same whether it occurs in a single stage or in several stages. That is, the sum of the ∆H of each stage of the reaction will give us a value equal to the ∆H of the reaction when it occurs in a single stage.

In this case you want to calculate the enthalpy change of:

C₂H₄ (g) + 6 F₂ (g) → 2 CF₄ (g) + 4 HF (g)

which occurs in three stages.

You know the following reactions, with their corresponding enthalpies:

Equation 1: H₂ (g) + F₂ (g) → 2 HF (g) ∆H° = -79.2 kJ/mol

Equation 2: C (s) + 2 F₂ (g) → CF₄ (g) ∆H° = 141.3 kJ/mol

Equation 3: 2 C(s) + 2 H₂ (g) → C₂H₄ (g) ∆H° = -97.6 kJ/mol

Because of the way formation reactions are defined, any chemical reaction can be written as a combination of formation reactions, some going forward and some going back.

<h3 /><h3>FIRST STEP</h3>

First, to obtain the enthalpy of the desired chemical reaction you need one mole of C₂H₄ (g) on reactant side and it is present in first equation. Since this equation has one mole of C₂H₄ (g) on the product side, it is necessary to locate it on the reactant side (invert it).

When an equation is inverted, the sign of ΔH° also changes.

<h3>SECOND STEP</h3>

Now, you need 2 moles of CF₄ (g) on the product side. The second equation has 1 mole of CF₄ (g) on the product side, so it is necessary to multiply it by 2 to obtain 2 moles of CF₄ (g).

Since enthalpy is an extensive property, that is, it depends on the amount of matter present, since the equation is multiply by 2, the variation of enthalpy also.

<h3>THIRD STEP</h3>

Finally, you need 4 moles of HF (g) on the product side. The first equation has 2 moles of HF (g) on the product side, so it is necessary to multiply it by 2 to obtain 4 moles of the compound.

Since the equation is multiply by 2, the variation of enthalpy also is multiplied by 2.

<h3>SUMMARY</h3>

In summary, you know that three equations with their corresponding enthalpies are:

Equation 1: 2 H₂ (g) + 2 F₂ (g) → 4 HF (g) ∆H° = -158.4 kJ/mol

Equation 2: 2 C (s) + 4 F₂ (g) → 2 CF₄ (g) ∆H° = 282.6 kJ/mol

Equation 3: C₂H₄ (g) → 2 C(s) + 2 H₂ (g) ∆H° = 97.6 kJ/mol

Adding or canceling the reactants and products as appropriate, and adding the enthalpies algebraically, you obtain:

C₂H₄ (g) + 6 F₂ (g) → 2 CF₄ (g) + 4 HF (g) ΔH°= 221.8 kJ/mol

Finally, the enthalpy change for the reaction is 221.8 kJ/mol.

Learn more about molar enthalpy:

7 0

2 years ago

PLEASE HELP

n200080 [17]

Mk i will comment so u can make them brainliest lols

6 0

3 years ago

Read 2 more answers

What causes pressure inside a helium balloon?

kupik [55]

Explanation:

So the gas pressure of a helium balloon arises from the impact of the collisions of the helium atoms between themselves and with the inside surface of the balloon. Of course, the outside atmosphere similarly exerts a pressure on the outside of the balloon.

7 0

3 years ago

3. At STP, how many liters of oxygen gas are required to react completely with 3.2 x 10^22

Mrrafil [7]

The volume of oxygen required to react with 3.2 * 10²² molecules of hydrogen is 0.56 L.

<h3>What is stoichiometric law?</h3>

The stoichiometric law has been given as the representation of the moles of product and reactant in a chemical reaction are represented by the stoichiometric coefficient.

It has been known that 1 mole of a compound has 6.023 * 10²³ molecules. Thus, the moles of hydrogen gas equivalent to 3.2 * 10²² molecules has been:

6.023 * 10²³ molecules = 1 mole

3.2 * 10²² molecules = 1/6.023 * 10²³ * 3.2 * 10²² moles

3.2 * 10²² molecules = 0.05 moles

Thus, the moles of hydrogen gas available is 0.05 moles.

From the stoichiometric law, according to the balanced chemical equation,

2 moles of hydrogen requires = 1 moles of oxygen

0.05 moles of hydrogen requires = 1/2 * 0.05 moles oxygen

0.05 moles of hydrogen requires = 0.025 moles oxygen

Thus, the moles of oxygen required is 0.025 moles. At STP, a mole of gas been equivalent to 22.4 L . Thus, the volume of 0.025 moles oxygen has been:

1 mole = 22.4 L

0.025 moles = 22.4 * 0.025 L

0.025 mole = 0.56 L

Thus, the volume of oxygen required to react with 3.2 * 10²² molecules of hydrogen is 0.56 L.

Learn more about stoichiometric law, here:

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7 0

2 years ago

When sodium and oxygen react to form an ionic compound, the mass of the compound ____ the sum of the masses of the individual el

Anna007 [38]

Hi Lara

The answer is : C

Is equal to

I hope that's help!