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90 POINTSSSS!!!

Katarina [22]

Answer:

$\large \boxed{\text{-2043.96 kJ/mol}}$

Explanation:

Assume the reaction is the combustion of propane.

Word equation: propane plus oxygen produces carbon dioxide and water

Chemical eqn: C₃H₈(g) + O₂(g) ⟶ CO₂(g) + H₂O(g)

Balanced eqn: C₃H₈(g) + 5O₂(g) ⟶ 3CO₂(g) + 4H₂O(g)

(a) Table of enthalpies of formation of reactants and products

$\begin{array}{cc}\textbf{Substance} & \textbf{$\Delta_{\text{f}}$H/(kJ/mol}) \\\text{C$_{3}$H$_{8}$(g)} & -103.85 \\\text{O}_{2}\text{(g)} & 0 \\\text{CO}_{2}\text{(g)} & -393.51 \\\text{H$_{2}$O(g)} & -241.82\\\end{array}$

(b)Total enthalpies of reactants and products

$\Delta_{\text{rxn}}H^{\circ} = \sum \left( \Delta_{\text{f}} H^{\circ} \text{products}\right) - \sum \left (\Delta_{\text{f}}H^{\circ} \text{reactants} \right)\\= \text{-2147.81 kJ/mol - (-103.85 kJ/mol)}\\= \text{-2147.81 kJ/mol + 103.85 kJ/mol}\\= \textbf{-2043.96 kJ/mol}\\\text{The enthalpy change is $\large \boxed{\textbf{-2043.96 kJ/mol}}$}$

ΔᵣH° is negative, so the reaction is exothermic.

5 0

3 years ago

Which of these functional groups is found in all amino acids? -NH2 -OH =O -PO42-

melisa1 [442]

Answer : The correct option is, $-NH_2$

Explanation :

Amino acid : The acid that contains two functional groups that are carboxylic group, $-COOH$ and ammine group, $-NH_2$ .

When the two or more that two amino acids join together with the help of peptide bond, they produces polypeptide chain or protein.

The bond present between the two amino acid is called a peptide bond.

The peptide bond is a chemical bond that is formed between the two molecules when the nitrogen of one amino acid react with the carbon of another amino acid by releasing a water molecule. This is a dehydration synthesis or condensation reaction.

From this we conclude that, only two functional groups carboxylic group, $-COOH$ and ammine group, $-NH_2$ are present in all amino acids.

Hence, the correct option is, $-NH_2$

7 0

3 years ago

Ni-cad (nickel–cadmium) batteries have a slightly lower cell potential than the common alkaline value of 1.5 v normally used in

Lorico [155]

The half-reaction are:

Cd ---> Cd(OH)₂
The oxidation number of Cd changed from 0 to +2. So, the number of mol electron transferred here is 2.

NiO(OH) --> Ni(OH)₂
The oxidation number of Cd changed from +3 to +2. So, the number of mol electron transferred here is 1.

Now, the greatest common factor would be 2. So, we use n=2 for the formula for ΔG°. F is Faraday's constant equal to 96,485 J/mol e.

ΔG° = nFE° = (2)(96,485)(1.5) =<em> 289,455 J</em>

6 0

3 years ago

When pellets of NaOH(s) are added to a flask of water, it is observed that the temperature of the water increases as the pellets

Nataly [62]

Answer: It is an exothermic process because heat energy is absorbed by the water as the NaOH(s) dissolves in it.

Explanation:

Endothermic reaction : It is a type of chemical reaction where the energy is absorbed from the surrounding. In the endothermic reaction, the reactant are less than the energy of product. In endothermic reaction, the change in enthalpy is, positive

Exothermic reaction : It is a type of chemical reaction where the energy is released into the surrounding. In the exothermic reaction, the energy of reactant are more than the energy of product. In exothermic reaction, the change in enthalpy is, negative.

Thus as energy is absorbed by water, which has been released by NaOH, the process is exothermic.

3 0

3 years ago

How are the molecular mass and molar mass of a compound similar and how are they different?

4vir4ik [10]

Answer:

Similarities: both state the mass of chemical species and they have the same numerical value

Differences: molecular mass refers to one single molecule and molar mass refers to one mole of a molecule

Explanation:

The molecular mass is the value of the mass of each molecule and it is measured in mass units (u). It is calculated adding the mass of each atom of the molecule.

The molar mass is the value of the mass of one mole of molecules, which means the mass of 6.022140857 × 10²³ molecules. The unit is g/mol.

For example, we can consider the methane molecule, which has the chemical formula of CH₄:

Molecular mass CH₄ = C mass + 4 x (H mass)

Molecular mass CH₄ = 12.01 + 4 x (1.01)

Molecular mass CH₄ = 16.05 u

Now to calculate the molar mass we multiply the value of the molecular mass by the Avogadro number and convert the units to g/mol:

Molar mass CH₄: 16.05 x $\frac{1}{6.022140857 x 10x^{23} } g$ x 6.022140857 × 10²³ mol⁻¹

Molecular mass CH₄ = 16.05 g / mol

5 0

3 years ago