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1 year ago

Consider the reaction. c2h5oh(l)⟶ c2h6(g)+12o2(g). state what further data would be needed to obtain δrh∘ at 500∘c and 1 bar.

1 answer:

6 0

For this type of problem, it is essential for you to have a data on the standard heats of formation of the substances given. For elemental substances or diatomic gases, the standard heat of formation is 0. Standard means the temperature is at 0°C and pressure at 1 atm. Calculate the standard heat of reaction using:

ΔH°rxn = ∑(Stoichiometric coefficient×ΔHf of products) - ∑(Stoichiometric coefficient×ΔHf of reactants)
Then, use this equation to find the reaction at T = 500°C and P = 1 bar:

ΔHrxn = ΔH°rxn + [∑(Stoichiometric coefficient×Cp of products) - ∑(Stoichiometric coefficient×ΔHf of reactants)]ΔT
So, you also need the Cp or specific heat capacities of the substances.

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For a particular reaction, ΔH∘=67.7 kJ/molΔH∘=67.7 kJ/mol and Δ????∘=126.9 J/(mol⋅K).ΔS∘=126.9 J/(mol⋅K). Assuming these values

Pavlova-9 [17]

Answer:

$T=533.49\, K$

For temperatures higher than 533.49 K we will see a spontaneous reaction, and for temperatures lower than that the reaction will not be spontaneous.

Explanation:

When are chemical reactions spontaneous? To find out we need to look at the reaction's change in Gibbs Free energy:

$\Delta G=\Delta H-T\Delta S$

When this is greater than zero, the reaction isn't spontaneous, when it is less than zero, we have a spontaneous reaction. The reaction must then change from spontaneous to non spontaneous when $\Delta G=0$ . If we insert that into our equation we get:

$0=\Delta H-T\Delta S\\\\T=\frac{\Delta H}{\Delta S}$

That is the temperature at which the reaction's spontaneity will change, plugging in our values we find:

$T=533.49\, K$

At that temperature we have $\Delta G=0$ .

Now, at a temperature greater than this one, the entropy term in our equation for the Gibbs' free energy of reaction will take over, and make $\Delta G$ , thus the reaction will be spontaneous.

On the other hand, if we lower the temperature, we will have a smaller entropy term, and we will have: $\Delta G>0$ . That is, the reaction will not be spontaneous. Therefore for temperatures higher than 533.49 K we will see a spontaneous reaction, and for temperatures lower than that the reaction will not be spontaneous.

8 0

2 years ago

One crystalline form of silica (SiO2) has a cubic unit cell, and from X-ray diffraction data it is known that the cell edge leng

Sav [38]

Answer:

8 Silicon atom are present in unit cell.

16 oxygen atoms are present unit cell.

Explanation:

Number of atoms in unit cell = Z =?

Density of silica = tex]2.32 g/cm^3[/tex]

Edge length of cubic unit cell = a = 0.700 nm = $0.700\times 10^{-7} cm$

$1 nm=10^{-7} cm$

Molar mass of Silica = $28.09 g/mol+16.00\times 2=60.09 g/mol$

Formula used :

$\rho=\frac{Z\times M}{N_{A}\times a^{3}}$

where,

$\rho$ = density

Z = number of atom in unit cell

M = atomic mass

$(N_{A})$ = Avogadro's number

a = edge length of unit cell

On substituting all the given values , we will get the value of 'a'.

$2.32 g/cm3=\frac{Z\times 60.09 g/mol}{6.022\times 10^{23} mol^{-1}\times (0.700\times 10^{-7}cm)^{3}}$

$Z = 8$

1 silicon is 2 oxygen atoms. then 8 silicon atoms will be 16 oxygen atoms.

5 0

2 years ago

What is the concentration of an alcl3 solution if 150. ml of the solution contains 550. mg of cl- ion?

valina [46]

The concentration of AlCl3 solution if 150 ml of the solution contains 550 mg of cl- ion is 0.0344 M

calculation

concentration = moles /volume in liters

volume in liters = 150 /1000= 0.15 L

number of moles calculation

write the equation for dissociation of Al2Cl3

that is AlCl3 ⇔ Al^3+ + 3 Cl ^-

find the moles of Cl^- formed

moles =mass/molar mass

mass in grams= 550/ 1000 =0.55 grams

molar mass of Cl^- =35.5 g/mol

moles is therefore= 0.55/35.5 =0.0155 moles

by use of mole ration betweem AlCl3 to Cl^- which is 1:3 the moles of AlCl3 is =0.0155 x 1/3= 5.167 x10^-3 moles

concentration of AlCl3 is therefore= 5.167 x10^-3/ 0.15 =0.0344 M

6 0

2 years ago

1. A student performs a reaction in a beaker by reaction silver nitrate with one long copper wire. The student’s thermometer cha

stiv31 [10]

Explanation:

The observation of student was that thermometer reading changed from 27°C to 35°C which indicates that temperature of the beaker solution rose after reaction due to release of heat during reaction as a product.

Those chemical reactions which gives heat energy as a product into their surrounding are categorized as exothermic reactions. During the course of these reaction temperature of the surroundings also increased.

So, this means that reaction between silver nitrate and copper wire is an exothermic reaction.

Three ways that the student could speed up the reaction :

By adding catalyst to the reaction.
By decreasing the temperature.
By increasing the concentration of silver nitarte solution.

3 0

2 years ago

Read 2 more answers

Naomi is investigating the properties of a solid material. It takes 120 joules to raise the temperature of 10 grams of the mater

MrRissso [65]

When heat energy is supplied to a material it can raise the temperature of mass of the material.
Specific heat is the amount of energy required by 1 g of material to raise the temperature by 1 °C.
equation is
H = mcΔt
H - heat energy
m - mass of material
c - specific heat of the material
Δt - change in temperature
substituting the values in the equation
120 J = 10 g x c x 5 °C
c = 2.4 Jg⁻¹°C⁻¹

3 0

2 years ago