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4 years ago

Which of the following molecules or ions is polar? (20 POINTS)

Chemistry

1 answer:

taurus [48]4 years ago

3 0

For NO3- molecule(fig.1)

1. Bonds are created between elements with different electronegativity, most bonds would be polar. Bonds in NO3 are polar.

2. In the geometry of the molecule bond polarities cancel out each other (since it is a vector) so NO3- ion molecule is non polar

3. Nitrate (NO3-)ion geometry would be trigonal planar

For CCl4 molecule(fig.2)

1. Bonds are created between elements with different electronegativity, most bonds would be polar. Bonds in CCl4 are polar.

2. It is a completely symmetrical molecule.

3.Carbon is the centre of CCl4 have four covalent bonds and it has no lone pairs. They are all equidistant the C-Cl bond polarities cancel out. So CCl4 molecule is non polar

For NH3 molecule(fig.3)

1. Bonds are created between elements with different electronegativity, most bonds would be polar. Bonds in NH3 molecule are polar.

2. it has a pyramidal structure.

3. the individual N-H bond dipoles don't cancel out. This dipole moment for the molecule indicates that NH3 is a polar molecule

For SF6 molecule(fig.4)

1.F is more electronegative than S. So the bonds are polar.

2. The symmetry of the molecule is symmetrical so that the dipole moments of bonds cancel correspond so the molecule is non-polar.

3. it has octahedral structure

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Doing an Endothermic reaction, what happens to energy in relation to the surroundings?

natali 33 [55]

Answer:

Doing an Endothermic reaction, energy is absorbed from surroundings

Explanation:

Endothermic reactions:

The type of reactions in which energy is absorbed are called endothermic reactions.

In this type of reaction energy needed to break the bond are higher than the energy released during bond formation.

For example:

C + H₂O → CO + H₂

ΔH = +131 kj/mol

it can be written as,

C + H₂O + 131 kj/mol → CO + H₂

we can see that 131 kj/mol energy is taken by the reactants. So energy is absorbed from surrounding.

Exothermic reaction:

The type of reactions in which energy is released are called exothermic reactions.

In this type of reaction energy needed to break the bonds are less than the energy released during the bond formation.

For example:

Chemical equation:

C + O₂ → CO₂

ΔH = -393 Kj/mol

it can be written as,

C + O₂ → CO₂ + 393 Kj/mol

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Which best describes a swimming pool?

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For the decomposition of A to B and C, A(s)⇌B(g)+C(g) how will the reaction respond to each of the following changes at equilibr

dangina [55]

Answer:

These are five different changes at equilibrium:

1) Double the concentrations of both products and then double the container volume

"No shift"

2) Double the container volume add more A

"Rightward shift"

3) Double the concentration of B and halve the concentration of C

"No shift"

4) Double the concentrations of both products

"Leftward shift"

5) Double the concentrations of both products and then quadruple the container volume

"No shift"

Explanation:

0) Equilibrium reaction

A(s) ⇌ B(g)+C(g)

In an equlibrium reaction the equilibrium constant is calculated from the species in gas or aqueous state. The concentration of the solid substances remains basically constant, so their concentrations are included in the equilibrium constant.

Hence, the equilibrium equation for this equation is given by the product of the concentrations of the products B and C, each raised to the power 1, because that is the stoichiometric coefficient of each one in the chemical equation.

Kc = [B] [C]

Following Le Chatelier principle, when a disturbance is produced in a chemical reaction at equilibrium such disturbance will be counteracted by a change that minimizes its effect trying to restore the equilibrium.

That will let us analyze the given changes.

1) Double the concentrations of both products and then double the container volume 

Since the equilibrium is proportional to the concentration of both products, see what the given changes cause.

The concentration of each species is proportional to the number of moles and inversely related to the volume. If you first double the concentration (without changing the volume) means that your are doubling the amount of moles, if then you doubles the volume you are restoring the original concentrations, and there is not a net change in the concentrations.

Hence, since the concentrations remain the same the equilibrium is not affected: no shift.

2) Double the container volume add more A.

You need to assume that adding more A, which is a solid compound, does not change the volume for the reaction. A normal assumption since the gas substances occupies a large volume compared with the solid substances.

As the concentration is inversely related to the volume, doubling the container volume will cut in half the concentrations of the gas products, B and C.

Since, the equilibrium is directly proportional to those concentrations, reducing the concentrations of both products will shift the equilibrium to the right, to produce more products, seeking to increase their concentrations and restore the equilibrium.

Conclusion: rightward shift.

3) Double the concentration of B and halve the concentration of C:

Call [B₁] the original concentration of B at equilibrium. When you double the concentration you get [B₂] = 2 [B].

Call [C₁] the original concentration of C at equilibrium. When you halve its concentration you get [C₂] = [C₁] / 2

Then, when you make the new product you get [B₂] [C₂] = 2 [B₁] [C₁] / 2 = [B₁] [C₁]

So, the product (the equilibrium) has not been changed and there is no shift.

4) Double the concentrations of both products

Now, both product concentrations have been increased, which is the most simple case to analyze, since you know that increasing the concentrations of one side will require a shift to the other side.

This is, to restore the equilibrium, more B and C must react to produce more A. Thus, the reverse reaction will be favored, i.e. the the reaction shall shift to the left.

5) Double the concentrations of both products and then quadruple the container volume

Doubling the concentration of both products means that the product of both concentrations wil be quadrupled (2[B] × 2[C] = 4 {B] [C] )

Since concentrations and volume are inversely related, the effect of quadrupling the volume will balance the effect of doubling both concentrations, and the effect is cancelled, no producing a net unbalance at the equilibrium, so no shift is produced.

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3 years ago