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Travka [436]
2 years ago
15

Which of these is an indication that a chemical reaction has occurred? (boiling of a substance ,freezing of a substance, formati

on of a gas, melting of a substance)
Chemistry
2 answers:
Readme [11.4K]2 years ago
8 0

Answer:

Boiling of a substance

Explanation:

When something is boiled, heat is released to the surrounding, making it an exothermic reaction (a type of chemical reaction)

Anna007 [38]2 years ago
5 0

Answer: the answer is formation of gas

Explanation: i took the qwiz and boliing water is wrong

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If 3 moles of a compound use 24 J of energy in a reaction, what is the A<br> Hreaction in J/mol?
erma4kov [3.2K]

Answer:

+8 J/mol

Explanation:

The following were obtained from the question:

Mole of the compound = 3 moles

Heat Energy used = 24J

Hreaction =?

The heat of reaction is the energy released or absorb during a chemical reaction. It is can obtained mathematically by the following equation:

Hreaction = Heat energy/mole

With the above equation, we can easily find the Hreaction for the question given as follow:

Hreaction = Heat energy/mole

Hreaction = 24J / 3mol

Hreaction = 8 J/mol

Since the compound used the energy, the Hreaction is +8 J/mol

8 0
3 years ago
How many protons are in nitrogen-15?
valentina_108 [34]
7 protons. As well as in nitrogen-14. The difference between nitrogen-14 and nitrogen-15 is in a number of neutrons. In nitrogen-14 - 7 neutrons, in nitrogen-15 - 8 neutrons. 
4 0
3 years ago
What coefficient of h+ balances the atoms in this half-reaction h+ + mno2 → mn2+ + h2o?
kvv77 [185]
The answer is 4 im pretty sure 
7 0
3 years ago
Read 2 more answers
Sodium aton has lower electron affinity than chlorine atom why
Citrus2011 [14]
Electron affinity is the energy released when an electron is accepted by a neutral atom forming a negative ion. Chlorine has the higher electron affinity because it readily accepts an electron to become more stable. On the other hand, sodium have to give up an electron to complete its valence shell.
5 0
3 years ago
Predict whether ΔS° is greater than, less than, or approximately zero for each of the following reactions, and explain your choi
inna [77]

Answer:

Explanation:

Entropy -

In a system, the randomness is measured by the term entropy .

Randomness basically refers as a form of energy that can not be used for any work.

The change in entropy is given by amount heat per change in temperature.

  • When solid is converted to gas entropy increases,

As the molecules in solid state are tightly packed and has more force of attraction between the molecules, but as it is converted to gas, the force of attraction between the molecule decreases and hence entropy increases.

So,

The particles of the substance , if are tightly held by strong force of attraction will decrease the entropy ,

And

If the particles are loosely held , the entropy will increase .  

  • If in a reaction , more number of gaseous atoms are present in the product side , entropy will increase , i.e. Δ°S > 0
  • When liquid is converted to solid entropy decreases,  

As the molecules in liquid state are loosely packed and has less force of attraction between the molecules, but as it is converted to solid, the force of attraction between the molecule increases and hence entropy decreases.

  • If in a reaction , less number of gaseous atoms are present in the product side , entropy will decrease , i.e. Δ°S < 0

From the question ,

( a )  NH₃(g) + 5 O₂(g) → 4 NO(g) + 6 H₂O(g)

Gaseous atoms -

Reactant - 1 + 5 = 6

Product - 4 + 6 = 10 ,

Hence ,

More number of gaseous atoms are present in the product side , So ,

entropy will increase , i.e. Δ°S > 0

( b ) CH₄(g) + 2 O₂(g) → CO₂(g) + 2 H₂O(g)

Gaseous atoms -

Reactant - 1 + 2 = 3

Product - 1 + 2 = 3 ,

Since ,

Both the side the value of gaseous atoms are , hence , Δ°S = 0 .

( c ) CaCO₃(s) → CaO(s) + CO₂(g)

Gaseous atoms -

Reactant = 0

Product - 0 + 1 = 1 ,

Since ,

Hence ,

More number of gaseous atoms are present in the product side , So ,

entropy will increase , i.e. Δ°S > 0

8 0
3 years ago
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