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2 years ago

Which of the following is consistent with a spontaneous process in the forward direction?

Chemistry

1 answer:

Kryger [21]2 years ago

7 0

Answer:

A) ∆Suniv >0, ∆G<0, T∆Suniv >0.

Explanation:

The connection between entropy and the spontaneity of a reaction is expressed by the second law of thermodynamics: The entropy of the universe increases in a spontaneous process and remains unchanged in an equilibrium process.

Mathematically, we can express the second law of thermodynamics as follows:

For a spontaneous process: ΔSuniv = ΔSsys + ΔSsurr > 0

Therefore, the second law of thermodynamics tells us that a spontaneous reaction increases the entropy of the universe; that is, ΔSuniv > 0.

If we want spontaneity expressed only in terms of the properties of the system (ΔHsys and ΔSsys), we use the following equation:

-TΔSuniv = ΔHsys - TΔSsys < 0

That means that T∆Suniv >0.

This equation says that for a process carried out at constant pressure and temperature T, if the changes in enthalpy and entropy of the system are such that ΔHsys - TΔSsys is less than zero, the process must be spontaneous.

Finally, if the change in free energy is less than zero (ΔG<0), the reaction is spontaneous in the forward direction.

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A 500 gram cube of lead is heated from 25 °C to 75 °C. How much energy was required to heat the lead? The specific heat of lead

Ludmilka [50]

Answer:

The energy required is 3225 Joules.

Explanation:

Given,

mass of lead cube = 500 grams

T₁ = 25°C

T₂ = 75°C

specific heat of lead = 0.129 J/g°C

Energy required to heat the lead can be found by using the formula,

Q = (mass) (ΔT) (Cp)

Here, ΔT = T₂ - T₁ = 75 - 25 = 50

Substituting the values,

Q = (500)(50)(0.129)

Q = 3225 Joules.

Therefore, energy required is 3225 J.

3 0

2 years ago

Two students are working together to build two models. Both models will represent the molecular structure of sodium bicarbonate,

vfiekz [6]

Answer:

Altogether for both models; two red jellybeans, two white jellybeans, two black jellybeans and six blue jellybeans.

Note: Since no specific color was stated for oxygen atoms, the answer assigns blue colored jellybeans to represent oxygen atoms.J

Explanation:

Sodium bicarbonate, NaHCO₃ is a compound composed of one atom of sodium, one atom of hydrogen, one atom of carbon and three atoms of oxygen.

Since red jellybeans represent sodium atoms, white jellybeans represent hydrogen atoms, black jellybeans represent carbon atoms and blue jellybeans represent oxygen atoms, each of the two students will require the following number of each jellybean for their model of sodium carbonate: One red jellybean, one white jellybean, one black jellybean and three blue jellybeans.

Altogether for both models; two red jellybeans, two white jellybeans, two black jellybeans and six blue jellybeans.

8 0

2 years ago

A 220.0 gram piece of copper is dropped into 500.0 grams of water 24.00 °C. If the final temperature of water is 42.00 °C, what

FrozenT [24]

Answer:

C. 481 °C.

Explanation:

At equilibrium:

The amount of heat absorbed by water = the amount of heat released by copper.

To find the amount of heat, we can use the relation:

Q = m.c.ΔT,

where, Q is the amount of energy.

m is the mass of substance.

c is the specific heat capacity.

ΔT is the difference between the initial and final temperature (ΔT = final T - initial T).

∵ Q of copper = Q of water

∴ - (m.c.ΔT) of copper = (m.c.ΔT) of water

m of copper = 220.0 g, c of copper = 0.39 J/g °C, ΔT of copper = final T - initial T = 42.00 °C - initial T.

m of water = 500.0 g, c of water = 4.18 J/g °C, ΔT of water = final T - initial T = 42.00 °C - 24.00 °C = 18.00 °C.

∴ - (220.0 g)( 0.39 J/g °C)(42.00 °C - Ti) = (500.0 g)(4.18 J/g °C)(18.00 °C)

∴ - (85.8)(42.00 °C - Ti) = 37620.

∴ (42.00 °C - Ti) = 37620/(- 85.8) = - 438.5.

∴ Ti = 42.00 °C + 438.5 = 480.5°C ≅ 481°C.

So, the right choice is: C. 481 °C.

4 0

2 years ago

How many moles of tungsten (W,183.85 g/lol are in 415 grams of tungsten?

vladimir1956 [14]

Given mass of tungsten, W = 415 g

Molar mass of tungsten, W = 183.85 g/mol

Calculating moles of tungsten from mass and molar mass:

$415 g * \frac{1 mol}{183.85 g} = 2.26 mol W$

7 0

2 years ago

Suppose that 0.323 g of an unknown sulfate salt is dissolved in 50 mL of water. The solution is acidified with 6M HCl, heated, a

geniusboy [140]

Answer:

1) 41.16 % = 0.182 grams

2) The alkali cation is K+ , to form the salt K2SO4

Explanation:

Step 1: Data given

Mass of unknown sulfate salt = 0.323 grams

Volume of water = 50 mL

Molarity of HCl = 6M

Step 2: The balanced equation

SO4^2- + BaCl2 → BaSO4 + 2Cl-

Step 3: Calculate amount of SO4^2- in BaSO4

The precipitate will be BaSO4

The amount of SO4^2- in BaSO4 = (Molar mass of SO4^2-/Molar mass BaSO4)*100 %

The amount of SO4^2- in BaSO4 = (96.06 /233.38) * 100

= 41.16%

So in 0.443g of BaSO4 there will be 0.443 * 41.16 % = 0.182 grams

2. If it is assumed that the salt is an alkali sulfate determine the identity of the alkali cation.

The unknown sulphate salt has 0.182g of sulphate. This means the alkali cation has a weight of 0.323-0.182 = 0.141g grams

An alkali cation has a chargoe of +1; sulphate has a charge of -2

The formula will be X2SO4 (with X = the unknown alkali metal).

Calculate moles of sulphate

Moles sulphate = 0.182 grams (32.1 + 4*16)

Moles sulphate = 0.00189 moles

The moles of sulphate = 0.182/(32.1+16*4)

The moles of sulphate = 0.00189 moles

X2SO4 → 2X+ + SO4^2-

For 2 moles cation we have 1 mol anion

For 0.00189 moles anion, we have 2*0.00189 = 0.00378 moles cation

Calculate molar mass

Molar mass = mass / moles

Molar mass = 0.141 grams / 0.00378 grams

Molar mass = 37.3 g/mol

The closest alkali metal is potassium. (K2SO4 )

3 0

2 years ago