1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
skelet666 [1.2K]
3 years ago
6

State hess's law.how is it used

Chemistry
2 answers:
Vesnalui [34]3 years ago
5 0
 <span>Hess' Law states that the enthalpy change in a reaction can be calculated from the enthalpy changes of reactions that, when combined, result in the desired reaction. 

For example, to check the enthalpy change that occurs when benzene undergoes incomplete combustion to water and carbon monoxide is not an easy task, because the products invariably contain CO2. However, by combining the reactions of the complete combustion of benzene and the combustion of CO, you can get the reaction you want. 

Reaction wanted: 2C6H6 + 9O2 → 12CO + 6H2O 
Reactions provided: 2C6H6 + 15O2 → 12CO2 + 6H2O and 2CO + O2 → 2CO2, and their associated ΔH. 

Rearrange the reactions so that, when they add up, they result in the wanted reaction. 

2C6H6 + 15O2 → 12CO2 + 6H2O (leave as is; no changes to ΔH) 
12CO2 → 12CO + 6O2 (reverse and multiply by 6; this changes the sign of ΔH and multiplies it by 6) 

Added up, it will result in 2C6H6 + 9O2 → 12CO + 6H2O. Add up the ΔH values for the rearranged reactions to find ΔH for this particular reaction.</span>
PSYCHO15rus [73]3 years ago
5 0

Answer: Hess's Law says the total enthalpy change does not rely on the path taken from beginning to end. Enthalpy can be calculated in one grand step or multiple smaller steps.

To solve this type of problem, organize the given chemical reactions where the total effect yields the reaction needed. There are a few rules that you must follow when manipulating a reaction.

The reaction can be reversed. This will change the sign of ΔHf.

The reaction can be multiplied by a constant. The value of ΔHf must be multiplied by the same constant.

Any combination of the first two rules may be used.

Finding a correct path is different for each Hess's Law problem and may require some trial and error.

You might be interested in
In the peptide GLVIW, the C-terminal end is ________.
zheka24 [161]
The peptide given above is made up of the following amino acids: glycine [G], leucine [L], valine [V], isoleucine [I] and tryptophan [W]. These amino acids are joined together by amide bond to form peptide. Peptides usually have two terminals, the N terminal and the C terminal. For GLVIW, the C terminal end amino acid is tryptophan, that is the last amino acid on the peptide chain. The N terminal amino acid is glycine, that is, the first amino acid on the peptide chain.
5 0
3 years ago
The limiting reactant in a reaction a. is the reactant for which there is the least amount in grams b. is the reactant which has
Shalnov [3]

Actually the correct answer must be:

The limiting reactant in the reaction is the one which has the lowest ratio of moles available over coefficient in the balanced equation

 

This is because the actual mass or number of moles of the reactant does not directly dictate if it is a limiting reactant, this must be relative to the other reactants.

 

So the answer is:

e. none of the above

5 0
3 years ago
what does ice cream melt on a hot day which type of thermal energy transfer does this melting represents
Rzqust [24]
Because the coldness in  the ice cream and the suns gamma rays are hitting the ice cream and then it will start to melt. and that is why ice cream melts.
6 0
3 years ago
Which of the following correctly describes alpha radiation?
umka2103 [35]
They can be stopped by a piece of paper.
7 0
3 years ago
Can salt dissolve in hydrogen peroxide? Pls help me
Genrish500 [490]

Answer:

Yes it can!!

Explanation:

Hydrogen peroxide mixed with sodium is known as oxygen bleach. Add water and the compound releases an oxygen molecule to help it lift mold and stains from the surface of natural materials.

3 0
3 years ago
Other questions:
  • which gas law would you use to calculate the new pressure for a gas when the volume of the trapped gas changes while the tempera
    13·2 answers
  • 1.) What are the two broad categories that elements can be divided into?
    11·1 answer
  • Some plants can grow from both blank and blank
    7·2 answers
  • During an investigation, a student burns magnesium to form magnesium oxide. The starting mass of magnesium is measured as 21.3 g
    9·1 answer
  • What two things do circuits have to have for them to work
    5·1 answer
  • What part of the sun do we see from earth?
    8·2 answers
  • QY
    15·1 answer
  • A tank at is filled with of sulfur tetrafluoride gas and of sulfur hexafluoride gas. You can assume both gases behave as ideal g
    11·1 answer
  • Question 8 (1 point)
    12·1 answer
  • Why do we need digital technology in school?​
    15·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!