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3 years ago

How do electronegativity values determine the charge distribution in a polar covalent bond?

Chemistry

1 answer:

sukhopar [10]3 years ago

6 0

Answer:

The polar covalent bonds are formed when the electronegativities of the atoms are different: the most electronegative atoms will pull the electrons with more strength, yielding a partial negative charge over the most electronegative atom and a partial positive charge over the least electronegative atom.

Explanation:

Covalent bond is the chemical bond where the electrons are shared.

A polar covalent bond is the covalent bond formed when the electrons are not shared equally.

Electronegativity is the relative attraction with which the atoms of an element attract the electrons in a covalent bond. The higher the electronegativity the higher the ability of the atoms to attract the electrons.

Thus, electronegativities are directly responsible for the polar character of the bonds: if the two atoms that form the polar bond have high electronegativity difference, then the most electronegative atom will pull the electrons with more strength, causing a partial negative charge over the most electronegative atom and a partial positive charge over the least electronegative atom. This is a polar covalent bond.

For example, fluoride, F, is the element with the highest electronegativiy (3.98). Hydrogen has electronegativy 2.2. So The bonds H - F, with electronegativity difference 3.98 - 2.2 = 1.78 are polar covalent bonds because F attracts the electrons more strongly than H does.

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Calculate the mass in grams of calcium carbonate present in a 50.00 mL sample of an aqueous calcium carbonate standard, assuming

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The units of ppm means parts per million. Also, It is equivalent to milligrams per liter. It is one way of expressing concentration of a substance. It usually used to describe the concentration of something in water or soil. We calculate the mass of CaCO3 as follows:

Mass = 75 mg/L (.050 L) = 3.75 mg CaCO3

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3 years ago

Chlorophyll a is one of the green pigments found in plants. Chlorophyll a has the molecular formula C55H72MgN4O5. How many atoms

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We add up all the various atoms:
C: 55
H: 72
Mg: 1
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55 + 72 + 1 + 4 + 5
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3 0

3 years ago

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Calcule a variação da entalpia dessa reação ( 2 NH3 (g) ---> CO(NH2)2 (s) + H2O (L) ) a partir das seguintes equações termoqu

Nitella [24]

ΔH = +438 kJ

We have three equations:

(I) N₂ + 3H₂ → 2NH₃; ΔH = -92 kJ

(II) H₂ +½O₂ → H₂O; ΔH = -286 kJ

(III) CO(NH₂)₂ + ³/₂O₂ → CO₂ + 2H₂O + N₂; ΔH = -632 kJ

From these, we must devise the target equation:

(IV) 2NH₃ + CO₂ → CO(NH₂)₂ + H₂O; ΔH = ?

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The target equation has 2NH₃ on the left, so you reverse equation (I).

When you reverse an equation, you reverse the sign of its ΔH.

(V) 2NH₃ → N₂ + 3H₂; ΔH = +92 kJ

Equation (V) has 1N₂ on the right, and that is not in the target equation.

You need an equation with 1N₂ on the left.

Reverse Equation (III).

(VI) CO₂ + 2H₂O + N₂ → CO(NH₂)₂ + ³/₂O₂; ΔH = +632 kJ

Equation (VI) has ³/₂O₂ on the right, and that is not in the target equation.

You need ³/₂O₂ on the left.

Multiply Equation (II) by three.

When you multiply an equation by three, you multiply its ΔH by three.

(VII) 3H₂ +³/₂O₂ → 3H₂O; ΔH = -286 kJ

Now, you add equations (V), (VI), and (VII), cancelling species that appear on opposite sides of the reaction arrows.

When you add equations, you add their ΔH values.

_______________________________________

We get the target equation (IV):

(V) 2NH₃ → N₂ + 3H₂; ΔH = + 92 kJ

(VI) CO₂ + 2H₂O + N₂ → CO(NH₂)₂ + ³/₂O₂; ΔH = +632 kJ

(VII) 3H₂ +³/₂O₂ → 3H₂O; ΔH = -286 kJ

(IV) 2NH₃ + CO₂ → CO(NH₂)₂ + H₂O; ΔH = +438 kJ

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3 years ago

Use the standard reaction enthalpies given below to determine ΔH°rxn for the following reaction:P4(g) + 10 Cl2(g) → 4PCl5(s) ΔH°

miskamm [114]

Answer: The $\Delta H^o_{rxn}$ for the reaction is -1835 kJ.

Explanation:

Hess’s law of constant heat summation states that the amount of heat absorbed or evolved in a given chemical equation remains the same whether the process occurs in one step or several steps.

According to this law, the chemical equation is treated as ordinary algebraic expressions and can be added or subtracted to yield the required equation. This means that the enthalpy change of the overall reaction is equal to the sum of the enthalpy changes of the intermediate reactions.

The given chemical reaction follows:

$P_4(g)+10Cl_2(g)\rightarrow 4PCl_5(s)$ $\Delta H^o_{rxn}=?$

The intermediate balanced chemical reaction are:

(1) $PCl_5(s)\rightarrow PCl_3(g)+Cl_2(g)$ $\Delta H_1=157kJ$ ( × 4)

(2) $P_4(g)+6Cl_2(g)\rightarrow 4PCl_3(g)$ $\Delta H_2=-1207kJ$

The expression for enthalpy of the reaction follows:

$\Delta H^o_{rxn}=[4\times (-\Delta H_1)]+[1\times \Delta H_2]$

Putting values in above equation, we get:

$\Delta H^o_{rxn}=[(4\times (-157))+(1\times (-1207))=-1835kJ$

Hence, the $\Delta H^o_{rxn}$ for the reaction is -1835 kJ.

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3 years ago

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Inessa05 [86]

C. released or absorbed.

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When the energy is absorbed, the reaction is called endothermic reaction

An example of exotermic reaction is between water and H2SO4

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3 years ago

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