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DedPeter [7]
3 years ago
6

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

Chemistry
1 answer:
lana [24]3 years ago
5 0

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

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When titrating a strong monoprotic acid and koh at 25°c, the ph will be less than 7 at the equivalence point. ph will be greater
iVinArrow [24]
By definition titraion of a monoprotic acid with means that the equivalence point implies netrality of the solution, which is pH = 7.

So, the answer is that pH will be equal to 7 at the equivalence.

Given that the acid is monoprotic and KOH has one OH- radical per molecule of KOH, the titration will require the same number of moles of acid than base to reach the equivalence point, as you can see in this equation, representing the monoprotic acid as HA:

 HA + KOH = K(+) + A(-) + H2O => 1 mol HA per 1 mol KOH.
8 0
3 years ago
The principal component of mothballs is naphthalene, a compound with a molecular mass of about 130 amu, containing only carbon a
DIA [1.3K]

Answer:

Empirical formula = C5H4

Molecular formula = C10H8

Explanation:

When the 3000 mg of naphthalene are burned they produce 10.3 mg of CO2. Knowing the unbalanced equation of the combustion of naphthalene, we have:

CxHy + O2 = CO2 + H2O

We calculate the molar composition of the sample. We look for the molecular weights in the periodic table:

CO2 = 12,011 + 2 (15,999) = 44,009 g

Mol C = 10.3 mg * (1 mol CO2 / 44.009 g CO2) * (1 mol C / 1 mol CO2) = 0.234 mmol C

Mass C = 0.234 mmol C * (12.011 g C / 1 mol C) = 2.8105 mg C

Mass H = 3 mg - 2.8105 mg = 0.1895 mg H

Mol H = 0.1895 mg H * (1 mol H / 1,008 g H) = 0.188 mmol H

To calculate the empirical formula, we must divide the number of moles of each element by the smallest number of moles, in this case, of hydrogen:

C = 0.2340 mmol C / 0.1895 mol H = 1.25

H = 0.1895 mmol H / 0.1895 mmol H = 1

We multiply the coefficients by 4, and we have the empirical formula:

C1.25 * 4H1 * 4 = C5H4

The molecular formula is equal to (C5H4)m, where m is calculated by the molecular and empirical mass ratio, as follows:

Empirical mass = (5 * 12.011) + (4 * 1.008) = 64.09 g

m = 130 g / 64.09 g = 2.02 = 2

Therefore we have the molecular formula:

(C5H4)2 = C10H8

4 0
3 years ago
What is the wavelength (in nm) of
LenKa [72]

Answer:

λ = 0.45×10⁻⁶ m

Explanation:

Given data:

Wavelength of blue light = ?

Frequency of blue light = 6.69×10¹⁴ s⁻¹

Solution:

Formula;

Speed of wave = wavelength × frequency

Speed of wave = 3.00×10⁸ m/s

by putting vales,

3.00×10⁸ m/s = λ × 6.69×10¹⁴ s⁻¹

λ = 3.00×10⁸ m/s / 6.69×10¹⁴ s⁻¹

λ = 0.45×10⁻⁶ m

6 0
3 years ago
Calculate the Standard Enthalpy of the reaction below:
Norma-Jean [14]

Answer:

(we use hess's law) it is so simple but the second reaction is not correct please right it

6 0
3 years ago
2. A shopper in a supermarket takes a box of sugar from a shelf that is 1.5 m high because he is
muminat

Explanation:

kinetic energy?? idek hope I helped in anyway possible

7 0
3 years ago
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