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2 years ago

How is hess's law used to calculate the enthalpy of a reaction apex?

Chemistry

2 answers:

Olenka [21]2 years ago

7 0

The desired enthalpy is obtained through adding intermediate reactions together. APEX

Kobotan [32]2 years ago

4 0

Hess's Law of Constant Heat Summation states that regardless of the multiple steps of a reaction, the total enthalpy change for the reaction is the sum of all changes. Thus, the enthalpy change is the same whether the reaction takes place in one step or in a series of steps. We can use Hess's Law by adding or subtracting chemical reactions with the same products or reactants.

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A 150 W electric heater operates for 12.0 min to heat an ideal gas in a cylinder. During this time, the gas expands from 3.00 L

Brut [27]

<u>Answer:</u> The change in internal energy of the gas is 108.835 kJ

<u>Explanation:</u>

To calculate the work done for reversible expansion process, we use the equation:

$W=P\Delta V=-P(V_2-V_1)$

where,

W = work done

P = pressure = 1.03 atm

$V_1$ = initial volume = 3.00 L

$V_2$ = final volume = 11.0 L

Putting values in above equation, we get:

$W=-(1.03)\times (11.0-3.00)=8.24L.atm=834.9J=0.835kJ$ (Conversion factor: 1 L. atm = 101.325 J)

Calculating the heat from power:

$Q=P\times t$

where,

Q = heat required

P = power = 150 W

t = time = 12 min = 720 s (Conversion factor: 1 min = 60 s)

Putting values in above equation:

$Q=150\times 720=108000J=108kJ$

The equation for first law of thermodynamics follows:

$Q=dU+W$

where,

Q = total amount of heat required = 108 kJ

dU = Change in internal energy = ?

W = work done = -0.835 kJ

Putting values in above equation, we get:

$108kJ=dU+(-0.835)\\\\dU=(108+0.835)=108.835kJ$

Hence, the change in internal energy of the gas is 108.835 kJ

7 0

2 years ago

At 1 atm, how many moles of co2 are released by raising the temperature of 1 liter of water from 20∘c to 25∘c? express your answ

tekilochka [14]

Answer is: 0,0030 mol of carbon dioxide.
Carbon dioxide solubility in water at 20°C and 1 atm is: 3,8·10⁻² mol/L.
Carbon dioxide solubility in water at 25°C and 1 atm is: 3,5·10⁻² mol/L.
Difference is: 0,038 mol/L - 0,035 mol/L = 0,003 mol/L.
V(carbon dioxide) = 1 L.
n(carbon dioxide) = V · c.
n(carbon dioxide) = 1 L · 0,003 mo/L.
n(carbon dioxide) = 0,0030 mol.

4 0

2 years ago

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In the top row labeled Before Collision, the left billiard ball labeled 3 meters per second approaches the right billiard ball l

True [87]

Answer:

Sample Response: Yes, the law of conservation of momentum is satisfied. The total momentum before the collision is 1.5 kg • m/s and the total momentum after the collision is 1.5 kg • m/s. The momentum before and after the collision is the same.

Explanation:

Sample Response since i just took it on Edg.

5 0

2 years ago

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Analyze the importance of chemistry in our society using the branches of chemistry as examples

ICE Princess25 [194]

Answer:

Explanation: Well each branch has its own little job especially when it comes to society. First we have the Organic Chemistry Branch It includes the study of all the possible compounds which have carbon in them. Then we have the Inorganic Chemistry Branch, the inorganic compounds find their use in medicine, food, agriculture and also technology. Next we have the Biochemistry Branch it deals with chemistry happening inside the living bodies of animals and plants. This subject is huge and plays an important role in medicine, agriculture, poultry, fisheries, etc. And finally we have the Physical Chemistry Branch it deals with the physical properties of chemicals or substances. It includes topics like gaseous laws (Dalton law), thermal conduction in liquids, gases, solids. The conductivity of electrolytes (used in batteries) liquids etc. It also deals with processes like sublimation, melting point, boiling point, the crystal structure of compounds, etc.

6 0

2 years ago

Recall that your hypothesis is that these values are the fraction of atoms that are still radioactive after n half-life cycles.

jolli1 [7]

Answer : A= 0.5, B = 0.25 , C = 0.125, D = 0.015625 and E = 0.00390625

Explanation :

Half life of a substance is defined as the amount of time taken by the substance to reduce to half of its original amount.

Here n represents the number of half lives.

The amount of substance that remains after n half lives can be calculated using the given formula, $0.5^{n}$

So when we have n =1,

Fraction of substance that remains = 0.5¹ = 0.5.

That means after first half life over, the amount of substance that remains is 0.5 times that of original.

Therefore we have A = 0.5

When n = 2, we have 0.5² = 0.25

So when 2 half lives are over, the amount of substance that remains is 0.25 times that of original

Therefore B = 0.25

When n = 3, we have 0.5³ = 0.125

So when 3 half lives are over, the amount of substance that remains is 0.125 times that of original.

Therefore we have C = 0.125

When n = 6 , we have 0.5⁶ = 0.015625

So D = 0.015625

When n = 8, we have 0.5⁸ = 0.00390625

Therefore E = 0.00390625

The values for A, B, C, D and E are 0.5, 0.25, 0.125, 0.015625 and 0.00390625 respectively.

8 0

2 years ago

Read 2 more answers