1. A recipe for s'mores calls for 2 graham crackers, 2 chocolate pieces and 1 marshmallow. If I

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

kaheart [24]

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.

8 0

3 years ago

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Instant cold packs, often used to ice athletic injuries on the field, contain ammonium nitrate and water separated by a thin pla

RSB [31]

<u>Answer:</u> The enthalpy change of the reaction is -27. kJ/mol

<u>Explanation:</u>

To calculate the mass of water, we use the equation:

$\text{Density of substance}=\frac{\text{Mass of substance}}{\text{Volume of substance}}$

Density of water = 1 g/mL

Volume of water = 25.0 mL

Putting values in above equation, we get:

$1g/mL=\frac{\text{Mass of water}}{25.0mL}\\\\\text{Mass of water}=(1g/mL\times 25.0mL)=25g$

To calculate the heat released by the reaction, we use the equation:

$q=mc\Delta T$

where,

q = heat released

m = Total mass = [1.25 + 25] = 26.25 g

c = heat capacity of water = 4.18 J/g°C

$\Delta T$ = change in temperature = $T_2-T_1=(21.9-25.8)^oC=-3.9^oC$

Putting values in above equation, we get:

$q=26.25g\tiimes 4.18J/g^oC\times (-3.9^oC)=-427.9J=-0.428kJ$

To calculate the number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$

Given mass of ammonium nitrate = 1.25 g

Molar mass of ammonium nitrate = 80 g/mol

Putting values in above equation, we get:

$\text{Moles of ammonium nitrate}=\frac{1.25g}{80g/mol}=0.0156mol$

To calculate the enthalpy change of the reaction, we use the equation:

$\Delta H_{rxn}=\frac{q}{n}$

where,

q = amount of heat released = -0.428 kJ

n = number of moles = 0.0156 moles

$\Delta H_{rxn}$ = enthalpy change of the reaction

Putting values in above equation, we get:

$\Delta H_{rxn}=\frac{-0.428kJ}{0.0156mol}=-27.44kJ/mol$

Hence, the enthalpy change of the reaction is -27. kJ/mol

4 0

3 years ago

Why does a beta particle have an atomic number of -1

Fudgin [204]

I cant entirely tell for now but an article on rodioactivity should solve the problem

6 0

3 years ago

Why does fluorine have the highest electronegativity

ICE Princess25 [194]

Answer:

Because it only needs one more electron to get to a full valence shell (8), so it really wants it and is pulling other electrons in. It also has to do with needing one more electron to fill the 2p shell. It is a small element which means its electrons are pulled tightly to the nucleus.

Hope this helps!

Explanation:

5 0

2 years ago

7. (04wP2-5)Elements with atomic number 21 to 30 are d-block elements.

Katyanochek1 [597]

Answer :

(a) zn

Explanation:

(b) a ligand is an ion or molecule that binds to the central metal atom to form a cordinate complex.
(c)

<h3> above</h3>

3 0

3 years ago