All categories

3 years ago

How does hess's law use intermediate reactions to calculate the enthalpy of a desired reaction?

2 answers:

8 0

Answer : Hess's law uses the intermediate reactions to calculate the enthalpy by the law of Constant Heat Summation which states that regardless of the multiple stages occurring in the reaction, the total enthalpy change for the reaction is the sum of all changes.

This law was a manifestation that enthalpy is a state function i.e it is irrespective of the path followed to reach the final state.

The application of Hess’s law, uses the standard heats of formation of the reactants and products to indirectly calculate the heat of reaction (enthalpy) for any reaction that occurs at standard conditions.

An enthalpy change which occurs specifically under standard conditions is called the standard enthalpy of reaction and is given the symbol ΔH°.

The standard heat of reaction can be calculated by using the given equation., i.e.;

ΔH° = Σn ΔH°f(products)−ΣnΔH°f(reactants)

Here, Σ represents “the sum of”

The standard heat of reaction is equal to the sum of all the standard heats of formation of the products subtracted by the sum of all the standard heats of formation of the reactants.

The letter “n” represents that each heat of formation must first be multiplied by its coefficient in the balanced equation.

____ [38]3 years ago

7 0

By adding the enthalpies of the intermediate reactions together to get the enthalpy of the desired reaction

You might be interested in

Put atom in order from most to lest

Andrej [43]

Answer:

francium, caesium, helium

7 0

3 years ago

In a first-order decomposition reaction, 50.0% of a compound decomposes in 10.5 min.

mihalych1998 [28]

In this reaction 50% of the compound decompose in 10.5 min thus, it is half life of the reaction and denoted by symbol $t_{1/2}$ .

(a) For first order reaction, rate constant and half life time are related to each other as follows:

$k=\frac{0.6932}{t_{1/2}}=\frac{0.6932}{10.5 min}=0.066 min^{-1}$

Thus, rate constant of the reaction is $0.066 min^{-1}$ .

(b) Rate equation for first order reaction is as follows:

$k=\frac{2.303}{t_{1/2}}log\frac{[A_{0}]}{[A_{t}]}$

now, 75% of the compound is decomposed, if initial concentration $[A_{0} ]$ is 100 then concentration at time t $[A_{t} ]$ will be 100-75=25.

Putting the values,

$0.066 min^{-1}=\frac{2.303}{t}log\frac{100}{25}=\frac{2.303}{t}(0.6020)$

On rearranging,

$t=\frac{2.303\times 0.6020}{0.066 min^{-1}}=21 min$

Thus, time required for 75% decomposition is 21 min.

8 0

3 years ago

You have placed a can of lemonade in a cooler of is ice.what is the best way to describe what is happening to the ice

Firdavs [7]

<span>Heat from the can is making the water molecule move faster, which melts the ice.</span>

6 0

3 years ago

Read 2 more answers

A bacterium is in a nasty environment. What sort of reproduction would it use in this situation? Why? How else would it protect

lana [24]

The bacteria in nasty environment undergoes multiple fission.

<h3><u>Explanation</u>:</h3>

The bacteria is a unicellular prokaryotic organisms that are found in each and every places of the world. They can survive in extremes of temperatures and pH. They can save themselves through special processes in the extreme climates.

The bacteria undergoes multiple fission in these climates. They cover themselves up with a strong and tough capsule inside which they undergo several Binary fissions. This leads to the formation of multiple cells enclosed with a capsule.

With the return of the favourable climate, the capsule rupture and these newly formed cells come out.

7 0

3 years ago

Which noble gas is closer to magnesium

cricket20 [7]

I believe Neon is closest to Magnesium on the Periodic Table of elements.

Sorry if I'm wrong, hope I could help though! :)

3 0

2 years ago