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posledela
1 year ago
6

During an exothermic reaction, ΔH for the reactants was 890 kJ/mol. Which of the following statements is correct about the ΔH fo

r the products?
A. It is less than 890 kJ/mol because the amount of energy required to break bonds is less than the amount of energy released in forming bonds.

B. It is less than 890 kJ/mol because the amount of energy required to break bonds is greater than the amount of energy released in forming bonds.

C. It is greater than 890 kJ/mol because the amount of energy required to break bonds is less than the amount of energy released in forming bonds.

D. It is greater than 890 kJ/mol because the amount of energy required to break bonds is greater than the amount of energy released in forming bonds.

Chemistry
2 answers:
kaheart [24]1 year ago
8 0

Answer:-A. It is less than 890 kJ/mol because the amount of energy required to break bonds is less than the amount of energy released in forming bonds.

Explanation: Endothermic reactions are defined as the reactions in which energy of the product is greater than the energy of the reactants. The total energy is absorbed in the form of heat and \Delta H for the reaction comes out to be positive.

Exothermic reactions are defined as the reactions in which energy of the product is lesser than the energy of the reactants. The total energy is released in the form of heat and \Delta H for the reaction comes out to be negative.

In the formation of new bonds more energy is released than is required to break the existing bonds, heat is released.

In the formation of bonds less energy is released than is required to break the existing bonds, heat is absorbed.

Tatiana [17]1 year ago
5 0

<u>Answer:</u> The correct answer is Option A.

<u>Explanation:</u>

Endothermic reactions are defined as the chemical reactions in which energy of products is more than the energy of the reactants. In these reactions, energy is absorbed by the system. The total enthalpy of the reaction (\Delta H) comes out to be positive.

Exothermic reactions are defined as the chemical reactions in which energy of reactants is more than the energy of the products. In these reactions, energy is released by the system. The total enthalpy of the reaction (\Delta H) comes out to be negative.

When in the formation of new bonds, more energy is released than the energy is required to break the existing bonds, then the heat is released and the reaction is exothermic in nature.

When in the formation of bonds, less energy is released than the energy is required to break the existing bonds, then the heat is absorbed and the reaction is endothermic in nature.

We are given:

An exothermic reaction in which energy of the reactants is 890 kJ/mol. In this process, the energy is getting released.

Hence, the correct answer is Option A.

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Using only the following elements P, Br, and Mg, give the formulas for:A. an ionic compound. B. a molecular compound with polar
Talja [164]

Answer:

<h2>1. Ionic compound- MgBr_2</h2><h2>2. Polar molecular compound- PBr_3</h2>

Explanation:

Mg is a metal that has 12 atomic numbers and thus its electronic configuration is 1s^22s^22p^63s^2. The outer most shell of this element has 2 electrons so it loses 2 electrons and thus form Mg^2^+ ions. Br is a nonmetal and has 35 atomic number so its electronic configuration is 1s^22s^22p^63s^23p^64s^23d^1^04p^5. Since its outermost shell has 7 electrons so it can accept one electron and thus forms Br^-. So magnesium ion and bromide ion combine and forms an ionic compound MgBr_2.

P is also a nonmetal and combine with Br with covalent bond and due to electronegativity differences form polar covalent compound such as PBr_3.

8 0
1 year ago
Place each charge form of alanine under the pH condition where it would be the predominant form. The pKa values for the carboxyl
damaskus [11]

Answer:

(A) pH < 1 the predominant form is the cation: H3C-C(H)(NH3+)-COOH  

(B) pH = pl the predominant form is the zwitterion H3C-C(H)(NH3+)-COO-

(C) pH > 11 the predominant form is the anion: H3C-C(H)(NH2)-COO-

(D) Does not occurs in any significant pH: H3C-C(H)(NH2)-COOH

Explanation:

Amino acids are bifunctional because they have an amine group and a carboxyl group. The amine group is a weak base and the carboxyl group is a weak acid, but the pKa of both groups will depend on the whole structure of the amino acid. Also, every amino acid has an isoelectric point (pI), which means the pH were the predominant form of the amino acid is the zwitterion. The structure of the alanine (CH3CH2NH2COOH) shows it has the carboxyl group at C1 with a pKa1 of 2.3  and the amino group at C2 whit the pKa2 of 9.7. The isoelectric poin (pI) of Alanine is 6. Consequently, the protonation of the molecule will depend on the pH of the solution. There are three possibilities:

1) If the pH is under the pKa of the carboxyl group (2.3) the predominant form will be with the amino group protonated, forming a cation (CH3CH(NH3+)COOH).

2) If the pH is between pKa1 (2.3) and pKa2 (9.7) the predominant form will be the zwitterion (CH3CH(NH3+)(COO-)).

3) If the pH is upper the pKa2 of the amino group (9.7) the predominant form will be with the carboxyl group deprotonated, forming an anion (CH3CHNH2(COO-)).

8 0
2 years ago
A flask contains 1/3 mole of h2 and 2/3 mol of he. Compare the force on the wall per impact of h2 relative to that for he.
densk [106]

The force on the wall is actually the pressure exerted by gas molecules

Higher the pressure more the force exerted on the walls of container

The pressure depends upon the number of molecules of a gas

In a mixture of gas the pressure depends upon the mole fraction of the gas

As given the mole fraction of He is more than that of H2 therefore He will exert more pressure on the wall

The ratio of impact will be

H2 / He = 2/3 / 1/3 = 2: 1

8 0
1 year ago
Read 2 more answers
What is the molal concentration of a solution made by dissolving 34.2 g of sucrose, c12h22o11 (molar mass 342.34 g/mol), in 125
Anna007 [38]
Molality is the number of moles of solute in 1 kg of solvent
number of moles of sucrose - mass of sucrose / molar mass
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therefore number of moles in 1000 g - 0.0999 / 125 x 1000 = 0.799 mol/kg
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7 0
2 years ago
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12. Penny can knit 4 rows of a sweater in 5
Evgesh-ka [11]

Answer:

6.25 hours

Explanation:

From the question;

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We need to determine the time it will take for her to knit 300 rows

4 rows = 5 minutes

300 rows = ?

= (300 × 5 ) ÷ 4

= 375 minutes

But, 1 hour = 60 minutes

Therefore;

= 375 ÷ 60

= 6.25 hours

Thus, it will take penny 6.25 hours to knit 300 rows

8 0
1 year ago
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