How do I calculate the standard enthalpy change for the following reaction at 25 °C ? MgCl2(s)+H2O(l) --> MgO(s)+2HCl(g)


Answer 1

The right response is H, S8(monoclinic), and Methane (g).

The enthalpy of production for these three substances is non-zero.

How do I calculate the standard enthalpy change for the following reaction at 25 °C ?

  • Start by calculating the volume change of your substance.Find the change in the substance's intrinsic energy.Calculate the atmospheric pressure there.
  • To calculate the change in enthalpy, plug in all of the following quantities to the equation H = Q + p * V:
  • Enthalpy change that occurs in a system when matter undergoes a certain chemical reaction when all of the reactants and products are in their standard states is known as the standard enthalpy of reaction (Hr).
  • The equation q = mcT, where m is the mass of the sample, c is the specific heat, and T is the temperature change, can be used to determine how much heat is gained or lost by a sample (q).
  • In order to calculate the heat of a reaction (enthalpy change of a reaction, H), bond energies and bond enthalpies can be used.
  • H(reaction) = total bond energies of broken and formed bonds minus total bond energies of newly formed bonds. mgcl2 aq)+ h2o = MGO S)+ 2hcl AQ)
  • MgO(s) + 2HCl(aq) MgCl2(aq) + H2O(1) will have an absolute neutralization enthalpy of -57.33 kJ mol-2. Answer and justification
  • HCl is an acid, while MgO is a metal oxide, a form of basis oxide.When bases and acids interact, they produce water and the salt (MgCl2) (H2O H 2 O ).
  • This is a neutralization reaction, also referred to as an acid-base reaction. Magnesium chloride and water are produced when magnesium oxide and hydrochloric acid interact.It goes like this: MgO(s)+2HCl(aq)MgCl2(aq)+H2O (l)
  • The amount of heat, or Q, is what we want to know.To do this, we would apply the formula Q = m•C•T.The beginning and final temperatures can be used to calculate the m, C, and T. It's not a redox reaction, though.
  • An acid-base neutralization reaction is taking place.All of the reaction's participants' oxidation numbers remain unchanged.Hope this was useful.

       To learn more about enthalpy change refer


Answer 2
Answer: MgCl2(s) + H2O(l) → MgO(s) + 2 HCl(g) 

Using the standard enthalpies of formation given in the source below: 

(−601.24 kJ) + (2 x −92.30 kJ) − (−641.8 kJ) − (−285.8 kJ) = +141.76 kJ 

MgCl2(s) + H2O(l) → MgO(s) + 2 HCl(g), ΔH = +141.76 kJ

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Why there is a dip in electronegativity for the elements Mn and Zn?


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What types of energy is the potential energy in the match transformed into when a person strikes and lights a match?


The correct answer to this question is mechanical energy transforms into thermal energy when a person strikes and lights a match. Thank you for posting your question. I hope this answer helped you. Let me know if you need more help. 

How many protons are there in 20.02 mol of neon (Ne)?


In order to determine the number of protons in 20.02 mol of Ne, we use Avogadro's number to convert the number of moles to number of atoms, 1 mol = 6.022 x 10^23 atoms. From there, we must know the number of protons in a Neon atom, which is 10. Thus, the formula will be:
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You have 180g of a radioactive substance. it has a half-life of 265 years answer


What mass will remain after 1325 years?
 Radioactive substances are those substances whose unstable atoms undergo spontaneous decay by emitting alpha, beta, or gamma radiations. Half life is the time taken by a radioactive isotope to decay by half its original mass. 
In this case, half life is 265 years,
New mass = original mass × (1/2)∧n where n is the number of half lives,
n = 1325/ 265 = 5
hence, new mass = 180 × (1/2)∧5
                             = 180 × 1/32
                             = 5.625 g
Therefore; a mass of 5.625 g will remain after 1325 years

Indicate whether the substance exists in aqueous solution (a) entirely in molecular form, (b) entirely as ions, (c) or as a mixture of molecules and ions. HF, CH3CN, NaClO4, Ba(OH)2



In aqueous solution, HF is an acid, exist as a mixture of molecules and ions

CH3CN is none of the above, entirely in molecular form

NaCIO4 is a salt, entirely as ions

Ba(OH)2 is a base, entirely as ions

The substance exists in aqueous solution entirely in molecular form is Methyl cyanide, entirely as ions is NaClO₄ & Ba(OH)₂ and HF as a mixture of molecules and ions.

What is aqueous solution?

Aqueous solutions are those solution in which water is present as a solvent and we know that nature of water is polar in water means it consist positive or negative charges.

  • HF is a weak acid and it shows partial dissociation only, so it is present in the mixture form of molecules and ions.
  • Methyl cyanide is a covalent molecule not dissolve in aqueous solution and present in the molecular form.
  • NaClO₄ is a salt and it is completely dissolve in aqueous solution and present in the ions form.
  • Ba(OH)₂ is a strong base and it is also completely dissociates into their ions.

Hence NaClO₄ & Ba(OH)₂ is completely dissociates into ions.

To know more about aqueous solution, visit the below link:


In the reaction of 6 moles of CH4 with excess oxygen, how many moles of water could be produced? A. 4 B. 6 C. 8 D. 12


*brings you good news*

The answer is D. 12 

Hope i will help you angain sometime :)


My homework says "during s chemical reaction _________ are arranged differently but none is missing"


Mass or material, both could work

given that the molar mass of Na2SO4 × nH2O is 322.1 g/mol calculate the number of moles of water in this hydrate


The molar mass of anhydrous Na₂SO₄ = [2(23) + 32 + 4(16)]
                                                                = 142 g/mol

If the molar mass of hydrated Na₂SO₄ = 322 g/mol

Since hydrated salt = Anhydrous Salt + Water

Then the mass of hydration (Water)= 322 g/mol - 142 g/mol    
                                                           = 180 g/mol

Since the molar mass of water itself is 18 g/mol
⇒ Moles of water = 180 g/mol ÷ 18g/mol
                              = 10

Thus n = 10; the formula of the hydrated salt is Na₂SO₄ · 10H₂O (Sodium Sulphate Decahydrate)

What is the molarity (M) of a solution with 2 mol of NaCl in 0.50 L of solution?



The answer to your question is 4 M



NaCl 2 moles

Volume = 0.5 l

Molarity = M


1.- Write the formula of Molarity


2.- Substitution


3.- Simplification and result

             Molarity = 4 M

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