Is a stable bond stronger?

The more stable a molecule (i.e. the stronger the bonds) the less likely the molecule is to undergo a chemical reaction.

chem.libretexts.org - 8.8: Strength of Covalent Bonds - Chemistry LibreTexts

Will TikTok delete inactive accounts?

There have been some rumors going around that this was actually TikTok purging inactive accounts, but this is completely false. As stated earlier,...

Last updated Aug 6, 2021

How do you know she's a good woman?

16 signs she's a high quality woman worth marrying 1) She knows she isn't all that's good in your life. ... 2) She doesn't beat around the bush....

Last updated Apr 18, 2022

Promotion

In proposing his theory that octets can be completed by two atoms sharing electron pairs, Lewis provided scientists with the first description of covalent bonding. In this section, we expand on this and describe some of the properties of covalent bonds. The stability of a molecule is a function of the strength of the covalent bonds holding the atoms together. Bonds between hydrogen and atoms in a given column in the periodic table are weaker down the column; bonds between like atoms usually become weaker down a column. Triple bonds between like atoms are shorter than double bonds, and because more energy is required to completely break all three bonds than to completely break two, a triple bond is also stronger than a double bond. Similarly, double bonds between like atoms are stronger and shorter than single bonds. Bonds of the same order between different atoms show a wide range of bond energies, however. Table \(\PageIndex{1}\) lists the average values for some commonly encountered bonds. Although the values shown vary widely, we can observe four trends:

The Relationship between Molecular Structure and Bond Energy

Bond energy is defined as the energy required to break a particular bond in a molecule in the gas phase. Its value depends on not only the identity of the bonded atoms but also their environment. Thus the bond energy of a C–H single bond is not the same in all organic compounds. For example, the energy required to break a C–H bond in methane varies by as much as 25% depending on how many other bonds in the molecule have already been broken (Table \(\PageIndex{2}\)); that is, the C–H bond energy depends on its molecular environment. Except for diatomic molecules, the bond energies listed in Table \(\PageIndex{1}\) are average values for all bonds of a given type in a range of molecules. Even so, they are not likely to differ from the actual value of a given bond by more than about 10%. Table \(\PageIndex{2}\): Energies for the Dissociation of Successive C–H Bonds in Methane. Source: Data from CRC Handbook of Chemistry and Physics (2004). Reaction D (kJ/mol) CH 4 (g) → CH 3 (g) + H(g) 439 CH 3 (g) → CH 2 (g) + H(g) 462 CH 2 (g) → CH(g) + H(g) 424 CH(g) → C(g) + H(g) 338 We can estimate the enthalpy change for a chemical reaction by adding together the average energies of the bonds broken in the reactants and the average energies of the bonds formed in the products and then calculating the difference between the two. If the bonds formed in the products are stronger than those broken in the reactants, then energy will be released in the reaction (\(ΔH_{rxn} < 0\)):

Does silence hurt a narcissist?

They will get fearful and nervous as soon as you begin ignoring them. This is what happens when you ignore a narcissist. They may start to obsess...

Last updated Aug 21, 2018

What are red flags when you first start dating?

Ever-changing: You're never good enough, and they're always trying to change you. Rudeness: They are dismissive or mean to your closest friends and...

Last updated Jan 7, 2022

Promotion

\[ ΔH_{rxn} \approx \sum{\text{(bond energies of bonds broken)}}−\sum{\text{(bond energies of bonds formed)}} \label{\(\PageIndex{1}\)} \] The ≈ sign is used because we are adding together average bond energies; hence this approach does not give exact values for ΔH rxn . Let’s consider the reaction of 1 mol of n-heptane (C 7 H 16 ) with oxygen gas to give carbon dioxide and water. This is one reaction that occurs during the combustion of gasoline:

\[\ce{CH3(CH2)5CH3(l) + 11 O2(g) \rightarrow 7 CO2(g) + 8 H2O(g)} \label{\(\PageIndex{2}\)} \]

In this reaction, 6 C–C bonds, 16 C–H bonds, and 11 O=O bonds are broken per mole of n-heptane, while 14 C=O bonds (two for each CO 2 ) and 16 O–H bonds (two for each H 2 O) are formed. The energy changes can be tabulated as follows: Binds Broken (kJ/mol) and Bonds Formed (kJ/mol) Bonds Broken (kJ/mol) Bonds Formed (kJ/mol) 6 C–C 346 × 6 = 2076 14 C=O 799 × 14 = 11,186 16 C–H 411 × 16 = 6576 16 O–H 459 × 16 = 7344 11 O=O 494 × 11 = 5434 Total = 18,530 Total = 14,086 The bonds in the products are stronger than the bonds in the reactants by about 4444 kJ/mol. This means that \(ΔH_{rxn}\) is approximately −4444 kJ/mol, and the reaction is highly exothermic (which is not too surprising for a combustion reaction). If we compare this approximation with the value obtained from measured \(ΔH_f^o\) values (\(ΔH_{rxn} = −481\;7 kJ/mol\)), we find a discrepancy of only about 8%, less than the 10% typically encountered. Chemists find this method useful for calculating approximate enthalpies of reaction for molecules whose actual \(ΔH^ο_f\) values are unknown. These approximations can be important for predicting whether a reaction is exothermic or endothermic—and to what degree. Example \(\PageIndex{1}\): Explosives The compound RDX (Research Development Explosive) is a more powerful explosive than dynamite and is used by the military. When detonated, it produces gaseous products and heat according to the following reaction. Use the approximate bond energies in Table \(\PageIndex{1}\) to estimate the \(ΔH_{rxn}\) per mole of RDX. Given: chemical reaction, structure of reactant, and Table \(\PageIndex{1}\). Asked for: \(ΔH_{rxn}\) per mole Strategy: List the types of bonds broken in RDX, along with the bond energy required to break each type. Multiply the number of each type by the energy required to break one bond of that type and then add together the energies. Repeat this procedure for the bonds formed in the reaction. Use Equation \(\PageIndex{1}\) to calculate the amount of energy consumed or released in the reaction (ΔH rxn ). Solution: We must add together the energies of the bonds in the reactants and compare that quantity with the sum of the energies of the bonds in the products. A nitro group (–NO 2 ) can be viewed as having one N–O single bond and one N=O double bond, as follows: In fact, however, both N–O distances are usually the same because of the presence of two equivalent resonance structures. A We can organize our data by constructing a table: Bonds Broken (kJ/mol) Bonds Broken (kJ/mol) Bonds Broken (kJ/mol) 6 C–H 411 × 6 = 2466 6 C=O 799 × 6 = 4794 3 N–N 167 × 3 = 501 6 O–H 459 × 6 = 2754 3 N–O 201 × 3 = 603 Total = 10,374 3 N=O 607 × 3 = 1821 1.5 O=O 494 × 1.5 = 741 Total = 7962 B From Equation \(\PageIndex{1}\), we have \[ \begin{align*} ΔH_{rxn} &\approx \sum{\text{(bond energies of bonds broken)}}−\sum{\text{(bond energies of bonds formed)}} \\[4pt] &= 7962 \; kJ/mol − 10,374 \; kJ/mol \\[4pt] &=−2412 \;kJ/mol \end{align*}

What makes you age faster?

Exposure to light is a top cause of premature aging: Sun exposure causes many skin problems. Ultraviolet (UV) light and exposure to sunlight age...

Last updated Sep 6, 2022

What keeps someone from cheating?

In a recent study, factors preventing cheating included concern about guilt, fear of a partner's reaction, and social stigma. High scores in...

Last updated Sep 15, 2022

Promotion

onumber \] Thus this reaction is also highly exothermic

chem.libretexts.org - 8.8: Strength of Covalent Bonds - Chemistry LibreTexts

Does sleeping next to someone make you emotionally closer?

Sleeping next to someone can also help promote deep REM sleep. Emotionally, sleeping next to someone means reduced anxiety, a sense of safety,...

Last updated Dec 13, 2019

How do you make your man happy in a relationship?

Compliment him. ... Tell him you appreciate what he does for you and your family. ... Make time for things to get hot in the bedroom. ... Be...

Last updated Nov 14, 2022

Promotion

What are the 5 stages of stress?

There are 5 stages of stress, knowing them can help you take action in the moment, to stop yourself spiralling out of control. Stage 1: Fight or...

Last updated Jan 19, 2019

Promotion

What does Romans 14 21 mean?

Honor Faith and Conscience First Their master is God and should work to please Him in their lives. Disciples who live like this should not judge or...

Last updated Aug 16, 2021