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3 years ago

Which of the following giant covalent structures does not have a high melting and boiling

Chemistry

2 answers:

iogann1982 [59]3 years ago

6 0

Answer:

Polythene has the lowest melting/boiling point from all the other covalent structures mentioned in this question.

vaieri [72.5K]3 years ago

5 0

Answer:

Polythene (polyethene according the IUPAC nomenclature.)

Explanation:

Consider the structure of each option:

Polythene: long chains of atoms that are able to rotate along the bonding axis.
Graphite: layers of (hexagonal) carbon sheets; each individual sheet is rigid (allows no rotation.)
Silicon dioxide: three-dimensional (tetrahedral) network of carbon and oxygen atoms; the entire network very rigid (allows no rotation.)
Diamond: three-dimensional (tetrahedral) network of carbon atoms; likewise, the entire tetrahedral network is very rigid.

Melting each structure requires overcoming the forces that hold the structure rigid:

In polythene, van der Waal forces hold the chains together and prevents rotations.
Deshaping graphite requires bending the layers; doing so would require overcoming the covalent bonds within the hexagonal sheets.
In silicon dioxide and diamond, deshaping the tetrahedral network also requires overcoming covalent bonds.

Van der Waal forces are much easier to break than covalent bonds.

Hence, the melting point of polythene would be the lowest among the options.

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For the net reaction: 2AB + 2C → A2 + 2BC, the following slow first steps have been proposed. AB → A + B 2C + AB → AC + BC 2AB →

puteri [66]

This is an incomplete question, here is a complete question.

For the net reaction: 2AB + 2C → A2 + 2BC, the following slow first steps have been proposed.

(1) AB → A + B

(2) 2C + AB → AC + BC

(3) 2AB → A₂ + 2B

(4) C + AB → BC + A

What rate law is predicted by each of these steps?

Answer : The rate law expression for the following reactions are:

(1) $\text{Rate}=k[AB]$

(2) $\text{Rate}=k[C]^2[AB]$

(3) $\text{Rate}=k[AB]^2$

(4) $\text{Rate}=k[C][AB]$

Explanation :

Rate law : It is defined as the expression which expresses the rate of the reaction in terms of molar concentration of the reactants with each term raised to the power their stoichiometric coefficient of that reactant in the balanced chemical equation.

The general reaction is:

$A+B\rightarrow C+D$

The general rate law expression for the reaction is:

$\text{Rate}=k[A]^a[B]^b$

where,

a = order with respect to A

b = order with respect to B

R = rate law

k = rate constant

$[A]$ and $[B]$ = concentration of A and B reactant

Now we have to determine the rate law for the given reaction.

(1) The balanced equations will be:

$AB\rightarrow A+B$

In this reaction, $AB$ is the reactant.

The rate law expression for the reaction is:

$\text{Rate}=k[AB]$

(2) The balanced equations will be:

$2C+AB\rightarrow AC+BC$

In this reaction, $C$ and $AB$ are the reactants.

The rate law expression for the reaction is:

$\text{Rate}=k[C]^2[AB]$

(3) The balanced equations will be:

$2AB\rightarrow A_2+2B$

In this reaction, $AB$ is the reactant.

The rate law expression for the reaction is:

$\text{Rate}=k[AB]^2$

(4) The balanced equations will be:

$C+AB\rightarrow BC+A$

In this reaction, $C$ and $AB$ are the reactants.

The rate law expression for the reaction is:

$\text{Rate}=k[C][AB]$

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4 years ago

Which of these is a compound? A)air B)sugar C12H22O11 C)the alloy steel D)nitrogen N

7nadin3 [17]

Nitrogen N I think would be the answer

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3 years ago

A 3.140 molal solution of NaCl is prepared. How many grams of NaCl are present in a sample containing 2.692 kg of water

S_A_V [24]

Answer:

494.49 g of NaCl.

Explanation:

Data obtained from the question include the following:

Molality of NaCl = 3.140 m

Mass of water = 2.692 kg

Mass of NaCl =.?

Next, we shall determine the number of mole of NaCl in the solution.

Molality is simply defined as the mole of solute per unit kilogram of solvent. Mathematically, it is expressed as

Molality = mole of solute /Kg of solvent

With the above formula, we can obtain the number of mole NaCl in the solution as follow:

Molality of NaCl = 3.140 m

Mass of water = 2.692 kg

Mole of NaCl =..?

Molality = mole of solute /Kg of solvent

3.140 = mole of NaCl /2.692

Cross multiply

Mole of NaCl = 3.140 x 2.692

Mole of NaCl = 8.45288 moles

Finally, we shall covert 8.45288 moles of NaCl to grams. This can be obtained as follow:

Mole of NaCl = 8.45288 moles

Molar mass of NaCl = 23 + 35.5 = 58.5 g/mol

Mass of NaCl =.?

Mole = mass /Molar mass

8.45288 = mass of NaCl /58.5

Cross multiply

Mass of NaCl = 8.45288 × 58.5

Mass of NaCl = 494.49 g.

Therefore, 494.49 g of NaCl are present in the solution.

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What happens when an electron absorbs energy

Eduardwww [97]

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Answer:

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