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3 years ago

Given that Delta.G for the reaction below is –957.9 kJ, what is Delta.Gf of H2O?

Chemistry

1 answer:

Alexxandr [17]3 years ago

8 0

Answer:

6ΔG°(f) H₂O = -229 Kj/mol

Explanation:

4NH₃(g) + 5O₂(g) => 4NO(g) + 6H₂O(g)

ΔG°(f) 4mol(-16.66Kj/mol) | 5mol(0Kj/mol) || 4mol(+86.71Kj/mol) | 6ΔG°(f) H₂O

Hess's Law

ΔG°(Rxn) = ∑ΔG°(f) Products - ∑ΔG°(f) Reactants

-957.9 Kj = [(4mol(+86.71Kj/mol)) + 6ΔG°(f) H₂O(g)] - [4mol(-16.66Kj/mol) + 5mol(0Kj/mol)]

-957.9 Kj = [4(86.7)Kj + 6ΔG°(f) H₂O] - [4(-16.66)Kj] = 346.84Kj + 6ΔG°(f) H₂O + 66.64Kj

ΔG°(f) H₂O = ((-957.9 - 346.84 -66.64)/6)Kj = -228.56 Kj ≅ -228.6 Kj*

*Verified with Standard Heat of Formation Table

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How is a crystal different from a solid made of individual molecules

Dmitry [639]

In a crystal, the molecules are closer together as they are in any solid. they have less room to move, and might even be combined together rather than individual

3 0

2 years ago

Barium sulfate is made by the following reaction.

ipn [44]

Answer:

%age Yield = 96 %

Explanation:

The balance chemical equation for given double replacement reaction is,

Ba(NO₃)₂ + Na₂SO₄ → BaSO₄ + 2 NaNO₃

Step 1: Calculate moles of Ba(NO₃)₂:

Moles = Mass / M.Mass

Moles = 75.1 g / 261.33 g/mol

Moles = 0.2873 moles of Ba(NO₃)₂

Step 2: Find out moles of BaSO₄ formed:

According to balance chemical equation,

1 mole of Ba(NO₃)₂ produced = 1 mole of BaSO₄

So,

0.2873 moles of Ba(NO₃)₂ will produce = X moles of BaSO₄

Solving for X,

X = 0.2873 mol × 1 mol / 1 mol

X = 0.2873 moles of BaSO₄

Step 3: Calculate Theoretical Mass of BaSO₄:

Mass = Moles × M.Mass

Mass = 0.2873 mol × 233.38 g/mol

Mass = 67.07 g of BaSO₄

Step 4: Calculate %age Yield as:

Theoretical Yield = 67.07 g

Actual Yield = 64.4 g

%age Yield = ???

Formula Used:

%age Yield = (Actual Yield ÷ Theoretical Yield) × 100

Putting Values,

%age Yield = (64.4 g ÷ 67.07 g) × 100

%age Yield = 96.01 % ≈ 96 %

6 0

2 years ago

At 73.0 ∘c , what is the maximum value of the reaction quotient, q, needed to produce a non-negative e value for the reaction so

damaskus [11]

Here we will use the general formula of Nernst equation:

Ecell = E°Cell - [(RT/nF)] *㏑Q

when E cell is cell potential at non - standard state conditions

E°Cell is standard state cell potential = - 0.87 V

and R is a constant = 8.314 J/mol K

and T is the temperature in Kelvin = 73 + 273 = 346 K

and F is Faraday's constant = 96485 C/mole

and n is the number of moles of electron transferred in the reaction=2

and Q is the reaction quotient for the reaction
SO42-2(aq) + 4H+(aq) +2Br-(aq) ↔ Br2(aq) + SO2(g) +2H2O(l)

so by substitution :

0 = -0.87 - [(8.314*346K)/(2* 96485)*㏑Q → solve for Q

∴ Q = 4.5 x 10^-26

6 0

2 years ago

A chemistry student weighs out 0.027 kg of an unknown solid compound X and adds it to 550. mL of distilled water at 30.° C. Afte

QveST [7]

Answer:

1. Yes

2.The solubility of X is 34.55g/L

Explanation:

Solubility of solute refers to how readily a solute will dissolve in a solvent at a particular temperature. Its the amount of moles or grams required to saturate 1dm $^{3}$ or 1 Litre of water.

From the problem, when the liquid was drained off and amount of X which didn't dissolve was measured, it weighed 0.008kg, this means out of 0.027kg, 0.027-0.008 actually dissolved

= 0.019kg*1000 = 19g.

if 19g is required to saturate 550mL at 30°C,

then $\frac{19*1000}{550}$ will saturate 1L

= 34.545g will saturate 1Litre

The solubility thus is 34.55g/L

5 0

3 years ago

How do the strength and the cohesion of clay-rich regolith or soil change with the addition of water?

lisov135 [29]

Answer:

Water lowers the strength and cohesion of clay-rich regolith or soil.

Explanation:

Water can seep into the soil or clay-rich regolith and replace the air in the pore space of the soil or regolith. Water will completely surrounds all the grains of the clay-rich regolith and breaks the bonds in between the grains, that is eliminating all grain to grain contact of the regolith. When the regolith becomes saturated with water, the angle of repose is reduced to very small values and the regolith tends to loose its form.

6 0

3 years ago