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2 years ago

Are bonds broken or formed, throughout each phase change present on a heating curve?

Chemistry

1 answer:

Blababa [14]2 years ago

5 0

Answer:

During a phase change no chemical bonds are broken. Atoms are not rearranged because a phase change is a physical change rather then a chemical change. However, intermolecular forces are almost entirely removed from the liquid since the intermolecular forces are what cause the liquid to be a liquid.

Explanation:the nature of the intermolecular forces (IMF) will not change when the state changes from solid to liquid, however, the number of IMF changes.

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The decomposition of copper(II) nitrate on heating is endothermic reaction. 2Cu(NO3)2(s) → 2C10(s) + 4NO2(g) + O2(g) Calculate t

Basile [38]

Answer:

The enthalpy change for the given reaction is 424 kJ.

Explanation:

$2Cu(NO_3)_2(s)\rightarrow 2CuO(s) + 4NO_2(g) + O_2(g),\Delta H_{rxn}=?$

We have :

Enthalpy changes of formation of following s:

$\Delta H_{f,Cu(NO_3)_2}=-302.9 kJ/mol$

$\Delta H_{f,CuO}=-157.3 kJ/mol$

$\Delta H_{f,NO_2}= 33.2 kJ/mol$

$\Delta H_{f,O_2}= 0 kJ/mol$ (standard state)

$\Delta H_{rxn}=\sum [\Delta H_f(product)]-\sum [\Delta H_f(reactant)]$

The equation for the enthalpy change of the given reaction is:

$\Delta H_{rxn}$ =

$=(2 mol\times \Delta H_{f,CuO}+4\times \Delta H_{f,NO_2}+1 mol\times \Delta H_{f,O_2})-(2mol\times \Delta H_{f,Cu(NO_3)_2})$

$\Delta H_{rxn}$ =

$(2mol\times (-157.3 kJ/mol)+4\times 33.2 kJ/mol=1 mol\times 0 kJ/mol)-(2 mol\times (-302.9 kJ/mol)$

$\Delta H_{rxn}=424 kJ$

The enthalpy change for the given reaction is 424 kJ.

6 0

3 years ago

How can I lucid dream?

xxMikexx [17]

Answer:

Set an alarm for five hours after your bedtime.

Go to sleep as usual.

When the alarm goes off, stay up for 30 minutes. Enjoy a quiet activity like reading.

Fall back asleep.

Explanation:

8 0

3 years ago

Read 2 more answers

What is the function of the cell wall in a cell

nadya68 [22]

Answer:

To support and protect the cell.

Explanation:

The cell was (only found in plant cells) are there to help the plasma membrane and help the plant hold its structure. If the cell wall wasn't there the plant would just flop onto the ground!

-Good luck-

7 0

3 years ago

One of the radioactive isotopes used in medical treatment or analysis is chromium-51. The half-life of chromium-51 is 28 days. H

Goryan [66]

Answer : The time required for decay is, 84 days.

Explanation :

Half-life of chromium-51 = 28 days

First we have to calculate the rate constant, we use the formula :

$k=\frac{0.693}{t_{1/2}}$

$k=\frac{0.693}{28\text{ days}}$

$k=0.0248\text{ days}^{-1}$

Now we have to calculate the time required for decay.

Expression for rate law for first order kinetics is given by:

$t=\frac{2.303}{k}\log\frac{a}{a-x}$

where,

k = rate constant

t = time taken by sample = ?

a = let initial activity of the sample = 100

a - x = amount left after decay process = 12.5

Now put all the given values in above equation, we get

$t=\frac{2.303}{0.0248}\log\frac{100}{12.5}$

$t=83.9\text{ days}\approx 84\text{ days}$

Therefore, the time required for decay is, 84 days.

7 0

3 years ago

Why does Hess's law allow you to determine the enthalpy change of a<br> reaction?

lana [24]

Enthalpy is a state function

Explanation:

The Hess's law allows us to determine the enthalpy change of a reaction because enthalpy is a state function. It does not depend on the individual path take in going from reactants to products in the reaction.

Enthalpy changes are the heat changes accompanying physical and chemical changes.
It is the difference between the heat content of product in the final state and the reactants.
Enthalpy changes for some reactions are not easily measurable experimentally.
To calculate such heat changes, we apply the Hess's law of heat summation.
The law states that "the heat change of a reaction is the same whether it occurs in a step or several steps".
The Hess's law is simply based on the first law of thermodynamics by which we know that energy is conserved in every system.

learn more:

Hess's law brainly.com/question/11293201

#learnwithBrainly

5 0

3 years ago