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Alika
2 days ago
7

Be sure to answer all parts. Calculate ΔH o for the following reaction in two ways, using the data given below. H2(g) + I2(g) →

2HI(g) (a) Using the equation ΔH o rxn = ∑(BE(reactants)) − ∑(BE(products)) kJ/mol (b) Using the equation ΔH o rxn = ∑(nΔH o f (products)) − ∑(mΔH o f (reactants)) kJ/mol Bond BE kJ/mol Substance ΔH o f kJ/mol H―H 436.4 H2(g) 0 I―I 151 I2(g) 61.0 H―I 298.3 HI(g) 25.9
Chemistry
1 answer:
alisha [2.7K]2 days ago
7 0
a) ΔH°rxn = -9.2kJ/mol b) ΔH°rxn = -9.2kJ/mol Explanation: By applying Hess's law, the reaction enthalpy ΔH can be calculated from the enthalpies of formation of the reactants and products involved, thus: ΔH°rxn = ∑(BE(reactants)) − ∑(BE(products)). Alternatively, it can be expressed as: ΔH°rxn = ∑(nΔH°f (products)) − ∑(mΔH°f (reactants)). For the given reaction: H₂(g) + I₂(g) → 2HI(g) a) Using the first equation, we find: ΔH°rxn = ΔH (H-H) + ΔH (I-I) - 2ΔHBE (H-I) = 436.4kJ + 151kJ - 2×298.3kJ. After the calculation, ΔH°rxn is determined to be -9.2kJ/mol. b) Based on the second equation: ΔH°rxn = 2ΔH°f (HI) − ΔH°f (H₂) - ΔH°f (I₂). Substituting the values yields ΔH°rxn = 2×25.9kJ - 0kJ - 61.0kJ. This also results in ΔH°rxn = -9.2kJ/mol.
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Which best describes the relationships between subatomic particles in any neutral atom? * 1 point the number of electrons equals
Tems11 [2387]

The atomic number corresponds to the number of protons

Protons are denoted as P and Electrons as E P = E

The atomic mass equals the sum of Neutrons and Protons

Atomic number = atomic mass = neutrons

P = E

Atomic mass - atomic number = Neutrons

Example:

Calcium consists of 20 Protons 20P = 20E

Atomic mass - atomic number = neutron count:)

4 0
8 days ago
Which of the following reactions is a redox reaction? (a) K2CrO4 + BaCl2 → BaCrO4 + 2KCl (b) Pb2+ + 2Br- → PbBr2 (c) Cu + S → Cu
castortr0y [2720]

(c) Cu + S → CuS is classified as a redox reaction

Explanation:

The following reactions are presented:

(a) K₂CrO₄ + BaCl₂ → BaCrO₄ + 2 KCl

(b) Pb²⁺ + 2 Br⁻ → PbBr₂

(c) Cu + S → CuS

Reaction (c) represents a redox reaction, as the oxidation states of the elements are changing. In this case:

Cu + S → CuS

In its elemental form, Cu has an oxidation state of 0, while in CuS (copper sulfide), its oxidation state changes to +2.

Similarly, S in its elemental form has an oxidation state of 0 and is -2 in CuS (copper sulfide).

Learn more about:

redox reactions

7 0
1 month ago
You have a racemic mixture of d-2-butanol and l-2-butanol. the d isomer rotates polarized light by +13.5∘. what is the rotation
Anarel [2593]
The L- isomer serves as the enantiomer of the D- isomer, and given that the optical rotation of the D- isomer is + 13.5°, the L- isomer's optical rotation will have the same magnitude but an opposite sign, resulting in -13.5°.

Thus, the rotation of the racemic mixture will be equal to 0°.


- This occurs because a racemic mixture contains equal proportions of both enantiomers.
8 0
1 month ago
How to calculate electronegativity with 3 elements?
VMariaS [2675]
For instance, what is the difference in electronegativity for Acetone(CH2O)? Are there two distinct values, namely 0.4 for C versus H and 1.0 for C versus O? How do you decide which one to adopt?

6 Comments

AlwaysReady1

•

Apr 3, 2016, 10:14 PM

I may not fully grasp the question, but if you’re seeking to determine a compound's electronegativity to assess its electron-attracting capability, there are various other influencing factors.

It varies depending on the compound. For example, CH2O, known as formaldehyde, has oxygen with two pairs of electrons that can be donated. Neither hydrogen nor carbon can bond further as they are already fulfilling their valence shell requirements.

Robo94

•



You're attempting to apply a concept from a binary system to a more complex one. I assume you're aiming to figure out a molecule's dipole moment. In the case of a diatomic molecule (where A is bonded to B), the potential difference can simply be determined as A minus B. For larger molecules, the calculations become much more involved.

If this inquiry is related to homework assistance, it’s a distinctly different method from what you might be accustomed to. I recommend starting with water and then expanding out from there.

Check this out: https://www.khanacademy.org/science/organic-chemistry/gen-chem-review/electronegativity-polarity/v/dipole-moment

Philosoaxolotl

•



Electronegativity pertains to single elements (or rather individual atoms) and lacks straightforward applicability to broader molecules.

What precisely are you aiming to do with this data? If you're delving into how electrons transition between molecules, the situation is more intricate—within a molecule, the more electronegative elements pull electrons from other atoms (which frequently happens in organic compounds, such as when oxygen bonds with carbon and pulls in some of its electrons). Nevertheless, this effect diminishes in lengthened molecules. The system is more complicated as molecules do not possess a single, constant electronegativity (which is more accurate for atoms); instead, they exhibit varied localized charge regions that will respond differently.

From what I gather, your question pertains to the electronegativity difference among the atoms within an acetone molecule. This indeed relies on which two atoms you are examining and won't remain constant throughout; however, the difference won't simply match the values listed in an electronegativity table due to the factors discussed earlier.

This explanation might seem a bit hazy, and I’m just an undergraduate, so please take my interpretation lightly, but I am open to clarifying further if needed.

cheeseborito

•



That statement is inaccurate.

Electronegativity represents the attraction an atom holds for the electrons in a covalent bond with another atom. Essentially, an element does not have a singular electronegativity; it fluctuates based on its bonding partners. We cannot discuss the electronegativity of an atom in isolation.

While average values are useful for practical discussions (though they may not capture the nuance), the effective electronegativity of an oxygen atom bonded to carbon will remain fairly consistent.

As far as my understanding goes, even though my definition of electronegativity may lack precision, the influence an oxygen atom has on the electrons of a carbon atom is affected by what the carbon is bonded to. For instance, the local charge around the oxygen in acetic acid will be more pronounced than that in decanoic acid.

I may have phrased the electronegativity issue poorly—what I meant was the interaction between pairs of atoms as related to one another. An oxygen will exert a consistent pull regarding a carbon atom, but the changes in local charge can differ due to the influence of surrounding atoms, making the topics we typically utilize electronegativity to clarify substantially more intricate.
6 0
1 month ago
What is the correct name for the ionic compound Ca2P5
Tems11 [2387]

Response:

The name of the compound is calcium phosphide.

Clarification:

Calcium phosphide is a salt-like substance formed from calcium and phosphorus in a 2:5 ratio. It is characterized by its red-brown crystalline appearance.

This compound is utilized as a rodenticide for exterminating rats.

Additionally, it can be employed in fireworks.

7 0
10 days ago
Read 2 more answers
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