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nikitadnepr [17]
3 years ago
5

The symbol ∆hf° stands for the _____. heat of reaction for a chemical reaction specific heat of a substance standard heat of for

mation for a compound heat capacity of a substance
Chemistry
1 answer:
mojhsa [17]3 years ago
3 0
ΔHfo stands for <span>standard heat of formation for a compound.

Heat of formation of compound is mathematically expressed as,
</span>∑Hproducts - ∑Hreactants
<span>
If value of </span>ΔHfo is negative, it suggest that is exothermic reaction. If ΔHfo is positive, it suggest that it is endothermic reaction. <span>


</span>
You might be interested in
An endergonic reaction with a Δh and Δs can be changed into an exergonic reaction.
zheka24 [161]

Full question:

This question is incomplete, here it is completed:

An endergonic reaction with a ______ ∆H and a ______ ∆S can be changed into an exergonic reaction by decreasing the temperature.

Option A: negative, positive

Option B: negative, negative

Option C: positive, positive

Option D: positive, negative

Answer:

Option B: negative, negative

Explanation:

The change in free energy (ΔG) of a system for a constant-temperature process is

ΔG = ΔH - TΔS

free energy is the energy available to do work. Thus, if a particular reaction is accompanied by a release of usable energy (that is, <u>ΔG is negative</u><u>), it is said to be</u><u> exergonic</u>. On the other hand, if a reaction consumes energy (that is, <u>ΔG is positive</u><u>), it is said to be </u><u>endergonic</u>.

Looking at the equation, we can see that if ΔH is negative and ΔS is negative, then ΔG will be negative only when TΔS  is smaller in magnitude than ΔH. This condition is met when T is small.

ΔG = ΔH - TΔS

           -        -

This means that the reaction proceeds spontaneously at low temperatures. At high temperatures, the reverse reaction becomes spontaneous. An example of that would be the following reaction:

NH₃(g) + HCl(g) → NH₄Cl(s)

4 0
3 years ago
What is the limiting reactant if 12 moles of p4 react with 15 moles of o2?.
brilliants [131]

Answer:

see explanation

Explanation:

To determine limiting reactant divide mole quantities of reactants by the respective coefficient in the balanced equation. The smaller value is the limiting reactant.

    P₄      +     5O₂       => 2P₂O₅

12/1 = 12      15/5 = 3

O₂ is the limiting reactant. P₄ will be in excess when rxn stops.

4 0
2 years ago
In this system, potential and kinetic energy are ________________ proportional.
brilliants [131]

Answer:

This question is incomplete

Explanation:

There are two major forms of energy; these are potential and kinetic energy. Kinetic energy is the energy present in moving options. Examples include mechanical and electrical energy.

The formula for kinetic energy is 1/2mv² where "m" is mass and "v" is velocity.

While potential energy is the energy present in stationary objects that can be put to use in future. Example includes a ball in its resting state. The formula for potential energy is "mgh" where "m" is mass, "g" is acceleration due to gravity and "h" is height

Considering the law of conservation of energy which states that energy can neither be created nor destroyed but can be transformed from one form to another. Looking at the example provided earlier for potential energy, a ball in its resting position (having a potential energy) when kicked will have a kinetic energy (which can be calculated with the formula provided earlier), hence

Total energy = potential energy (P.E) + kinetic energy (K.E)

This formula and the explanation above can be used to answer the completed question.

NOTE: There is no standard relationship between P.E and K.E. They could be directly or indirectly proportional depending on the circumstance.

5 0
3 years ago
Neptunium-237 undergoes a series of α-particle and β-particle productions to end up as thallium-205. How many α particles and β
Fantom [35]
<h3>Answer:</h3>

8 alpha particles

4 beta particles

<h3>Explanation:</h3>

<u>We are given;</u>

  • Neptunium-237
  • Thallium-205
  • Neptunium-237 undergoes beta and alpha decay to form Thallium-205.

We are required to determine the number of beta and alpha particles produced to complete the decay series.

  • We need to know that when a radioisotope emits an alpha particle the mass number reduces by 4 while the atomic number decreases by 2.
  • When a beta particle is emitted the mass number of the radioisotope increases by 1 while the atomic number remains the same.

In this case;

Neptunium-237 has an atomic number 93, while,

Thallium-205 has an atomic number 81.

Therefore;

²³⁷₉₃Np → x⁴₂He + y⁰₋₁e + ²⁰⁵₈₁Ti

We can get x and y

237 = 4x + y(0) + 205

237-205 = 4x

4x = 32

 x = 8

On the other hand;

93 = 2x + (-y) + 81

but x = 8

93 = 16 -y + 81

y = 4

Therefore, the complete decay equation is;

²³⁷₉₃Np → 8⁴₂He + 4⁰₋₁e + ²⁰⁵₈₁Ti

Thus, Neptunium-237 emits 8 alpha particles and 4 beta particles to become Thallium-205.

5 0
3 years ago
write the chemical formula for the following compound -magnesium chloride, zinc sulphide Sodium,sodium sulphate, calcium bicarbo
Sindrei [870]

Answer:

magnesium chloride: MgCl2

zinc sulphide: ZnS

sodium sulphate: Na2SO4

calcium bicarbonate: Ca(HCO3)2

6 0
3 years ago
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