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ludmilkaskok [199]
3 years ago
6

Consider the reaction ch3oh(l)→ch4(g)+1/2o2(g). part a calculate δrh∘298.

Chemistry
2 answers:
Vsevolod [243]3 years ago
8 0
To determine the standard heat of reaction, ΔHrxn°, let's apply the Hess' Law.

ΔHrxn° = ∑(ν×ΔHf° of products) - ∑(ν×ΔHf° of reactants)
where
ν si the stoichiometric coefficient of the substances in the reaction
ΔHf° is the standard heat of formation

The ΔHf° for the substances are the following:
CH₃OH(l) = -238.4 kJ/mol
CH₄(g) = -74.7 kJ/mol
O₂(g) = 0 kJ/mol

ΔHrxn° = (1 mol×-74.7 kJ/mol) - ∑(1 mol×-238.4 kJ/mol)
ΔHrxn° = +163.7 kJ
Feliz [49]3 years ago
5 0

Answer:

\Delta _rH^o=163.53kJ/mol

Explanation:

Hello,

In this case, the proper way to compute the enthalpy of reaction is as shown below:

\Delta _rH^o=\Delta _fH^o_{CH_4}+\frac{1}{2} \Delta _fH^o_{O_2}-\Delta _fH^o_{CH_3OH}

Wherein all the enthalpy changes are referred to the formation enthalpy which are subsequently replaced for each compound at its corresponding phase as follows:

\Delta _rH^o=-74.87kJ/mol+0kJ/mol-(-238.4kJ/mol)\\\Delta _rH^o=163.53kJ/mol

Best regards.

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If copper carbonate system is heated for too short a time, what will you notice for mass percent of copper be too large or too s
sammy [17]

Answer:

The mass percent of copper as element is the same.

Explanation:

First of all we need the reaction that is presented below:

CuCO_{3 (s)} +Heat → CuO_{(s)} + CO_{2 (g)}

The mass percent of copper (Cu) as element is the same because of during the reaction the element only transform its nature from copper carbonate (CuCO_{3 (s)}) to copper oxide (CuO_{(s)}), the latter is a solid and will remain in the system.

On the other hand, you will note that the global percentage mass will be small because of the reaction produce (CO_{2 (g)}) that is a gas and this one will escape for the system.  

Have a great day!

3 0
3 years ago
Balance the following equation:
Firdavs [7]

Answer: a) 2K_2CrO_4+3Na_2SO_3+10HCl\rightarrow 4KCl+3Na_2SO_4+2CrCl_3+5H_2O

b) 1 mole of SO_2 is produced.

Explanation:

According to the law of conservation of mass, mass can neither be created nor be destroyed. Thus the mass of products has to be equal to the mass of reactants. The number of atoms of each element has to be same on reactant and product side. Thus chemical equations are balanced.

The skeletal equation is:

K_2CrO_4+Na_2SO_3+HCl\rightarrow KCl+Na_2SO_4+CrCl_3 +H_2O

The balanced equation will be:

2K_2CrO_4+3Na_2SO_3+10HCl\rightarrow 4KCl+3Na_2SO_4+2CrCl_3+5H_2O

Thus the coefficients are 2, 3 , 10 , 4 , 3 , 2 and 5.

b) Oxidation: 2I-^-\rightarrow I_2+2e-^-

Reduction: SO_4^{2-}+2e^-+4H^+\rightarrow SO_2+2H_2O

Net reaction:  2I-^-+SO_4^{2-}+4H^+\rightarrow I_2+SO_2+2H_2O

When 1 mole of I_2 is produced, 1 mole of SO_2 is produced.

8 0
3 years ago
If cells in the process of dividing are subjected to colchicine, a drug that interferes with the formation of the spindle appara
Orlov [11]

The question is incomplete as it does not have the options which are:

A) anaphase

B) prophase

C) telophase

D) metaphase

E) interphase

Answer:

The correct answer will be option-D

Explanation:

Colchicine is a drug obtained from the <em>Colchicum autumnale</em> which is a poisonous European flowering plant. The drug is used to treat joint swelling and gout.

Colchicine shows its effect during the cell division cycle especially during the division of nuclear content. When the cell is in metaphase and is preparing for the anaphase, the colchicine inhibits the polymerisation of the microtubules. The inhibition of microtubules inhibits the assembly of the mitotic spindle as a result of this the DNA do not move into new daughter cells.

Thus, option-D is the correct answer.

5 0
3 years ago
An obese man was discovered in his air-conditioned hotel room sitting in a chair in front of the television. The air conditioner
Leno4ka [110]

Answer:

It has been approximately 6 hours after death.

Explanation:

This is because between 2-6 hours after death, the body starts becoming stiff from top to bottom, then spreading to the limbs. Since there is only rigor in his upper body, that would mean that with normal temperature and body conditions, it would be 4 or 5 hours after death. But since he is obese and in cold temperature, there is slower progression of rigor, leading to the maximum time in the first rigor mortis phase, 6 hours.

8 0
3 years ago
Which statement best describes the structure of covalent network solids? A. They are giant structures held together by weak forc
konstantin123 [22]

Answer: Option (B) is the correct answer.

Explanation:

A covalent compound is a compound formed by sharing of electrons. And, in a covalent network solid atoms are bonded by covalent bonds in a continuous network that is extending throughout the material or solid.

This continuous arrangement of atoms are like a lattice.

For example, diamond is a covalent network solid in which carbon atoms are arranged in a continuous lattice like structure.

Hence, we can conclude that the statement all the atoms are covalently bonded to other atoms to form a lattice-like structure, best describes the structure of covalent network solids.

6 0
3 years ago
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