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My name is Ann [436]
3 years ago
8

Which example involves a phase change in which heat energy is released by the substance

Chemistry
1 answer:
a_sh-v [17]3 years ago
7 0

What are the examples?


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Calculate the mass of water formed when 4g of methane is burnt in excess oxygen​
wariber [46]

Answer:

Mass of water formed: 9g

Explanation:

Hope it helps you!

6 0
2 years ago
he rate constant of a certain reaction is known to obey the Arrhenius equation, and to have an activation energy . If the rate c
Leya [2.2K]

The question is incomplete, here is the complete question:

The rate constant of a certain reaction is known to obey the Arrhenius equation, and to have an activation energy Ea = 71.0 kJ/mol . If the rate constant of this reaction is 6.7 M^(-1)*s^(-1) at 244.0 degrees Celsius, what will the rate constant be at 324.0 degrees Celsius?

<u>Answer:</u> The rate constant at 324°C is 61.29M^{-1}s^{-1}

<u>Explanation:</u>

To calculate rate constant at two different temperatures of the reaction, we use Arrhenius equation, which is:

\ln(\frac{K_{324^oC}}{K_{244^oC}})=\frac{E_a}{R}[\frac{1}{T_1}-\frac{1}{T_2}]

where,

K_{244^oC} = equilibrium constant at 244°C = 6.7M^{-1}s^{-1}

K_{324^oC} = equilibrium constant at 324°C = ?

E_a = Activation energy = 71.0 kJ/mol = 71000 J/mol   (Conversion factor:  1 kJ = 1000 J)

R = Gas constant = 8.314 J/mol K

T_1 = initial temperature = 244^oC=[273+244]K=517K

T_2 = final temperature = 324^oC=[273+324]K=597K

Putting values in above equation, we get:

\ln(\frac{K_{324^oC}}{6.7})=\frac{71000J}{8.314J/mol.K}[\frac{1}{517}-\frac{1}{597}]\\\\K_{324^oC}=61.29M^{-1}s^{-1}

Hence, the rate constant at 324°C is 61.29M^{-1}s^{-1}

8 0
3 years ago
1. It has been suggested that pain results from a change in the pH of solutions that surround nerves in the body.
Akimi4 [234]

Answer:

See Explanation

Explanation:

According to the question, it is established that the pain caused by a lot of insect bites owes to the acidity of the insect bites.

If this is true, then there is an urgent need to neutralize the acidic insect bite using a basic substance.

Hence the pH of the creams used to treat insect bites should be basic(having a high pH).

2. The compound methene can not exist because it is supposed to be derived from the alkane called methane which contains only one carbon atom.

In order to form an alkene, there must be a double bond between two carbon atoms. This is not possible because there is only one carbon atom in the hypothetical methene. Hence,  a compound named methene cannot exist.

3 0
3 years ago
Isn’t urgent the first 3 will be marked BRAINIEST
bearhunter [10]

Answer:

Al2(SO4)3 and Mg(OH)2

Explanation:

1. Al has a charge of 3-, and SO4 of 2-

when you cross multiply the charges you get

Al2 and (SO4)3

*the reason theres a bracket around the sulfate ion is that the charge 3 is not for oxygen only, but the entire sulphate ion*

Hence, Al2(SO4)3

2. Mg has a charge of 2- and OH of 1-

again cross multiply

Mg (you dont need to add the 1) and (OH)2

again, the bracket around OH means the charge appiles to Oxygen AND hydrogen

hence, Mg(OH)2

7 0
3 years ago
Read 2 more answers
Which one of these best defines climate
lisabon 2012 [21]

Answer:

Long term condition of the atmosphere

Explanation:

I think this is right.

I hope this helps! (✿◕‿◕✿)

3 0
3 years ago
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