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
S_A_V [24]
3 years ago
6

How do you work out question 1a?

Chemistry
1 answer:
Sliva [168]3 years ago
4 0

Answer:

-125 kJ

Explanation:

You calculate the energy required to break all the bonds in the reactants. Then you subtract the energy to break all the bonds in the products.

                     H₂C=CH₂   +    H₂ ⟶    H₃C-CH₃

Bonds:       4C-H + 1C=C     1H-H     6C-H + 1C-C

D/kJ·mol⁻¹:  413       612        436       413      347

The formula relating ΔHrxn and bond dissociation energies (D) is

ΔHrxn = Σ(Dreactants) – Σ(Dproducts)

(Note: This is an exception to the rule. All other thermochemical reactions are “products – reactants”. With bond energies, it’s “reactants – products”. The reason comes from the way we define bond energies.)

<em>For the reactant</em>s:

Σ(Dreactants) = 4 × 413 + 1 × 612 + 1 × 436 = 2700 kJ

<em>For the products:</em>

Σ(Dproducts) = 6 × 413 + 1 × 347 = 2825 kJ

<em>For the system</em> :

ΔHrxn = 2700 - 2825 = -125 kJ

You might be interested in
The teal line of the hydrogen emission spectrum has a wavelength of 486.0 nm. A hydrogen emission spectrum has a violet, a blue,
Sloan [31]

Answer:

The correct answer to the following question will be "4.08 × 10⁻¹⁹ Joule".

Explanation:

Given:

Wavelength, λ = 486.0 nm

As we know,

E=h\upsilon =\frac{hc}{\lambda}

On putting the estimated values, we get

⇒          =\frac{1241.5 \ ev\ nm}{486 \ nm}

⇒          =2.554 \ ev

∴ 1 ev = 1.6 × 10⁻¹⁹ J

Now,

Energy, E=2.554\times 1.6\times 10^{-19}

⇒               =4.08\times 10^{-19} Joule

7 0
2 years ago
In which of the following substances does sharing of electrons between two atoms occur?
Ilya [14]

Answer:

Explanation:

CO2

3 0
3 years ago
While exploring on your grandfathers farm, you find a layer of charcoal that might represent a campfire built by Native American
Ierofanga [76]
Carbon Dating would tell you the age of the charcoal
8 0
3 years ago
Jon is running for city council and wants to campaign on human development goals for his community. Which issue should he use? A
kotegsom [21]

Answer:

E. better schools

Explanation:

This contributes the most to human development in his community because it provides children with more resources and better opportunities than a sub-par education system. If a community is able to better their school system, they will begin to see a lot of positive changes in their area.

6 0
3 years ago
Read 2 more answers
Determine the molar concentration of HCL required if 40cm^3 of HCL is reacted with 36g of magnesium via this equation.
Art [367]

The answer is in the photo.

4 0
3 years ago
Other questions:
  • Which of the following is a starting compound during cellular respiration? Carbon dioxide Glucose Mitochondria Water
    8·2 answers
  • Which is a mixture?
    15·2 answers
  • Mg + __C12 = ____MgCl2
    15·1 answer
  • Approximately how old is the Sun?
    11·2 answers
  • Which of the following stages would come first in the life of a star? Neutron star White dwarf Protostar Black hole
    9·1 answer
  • A part of the periodic table is shown below:
    9·2 answers
  • Please help fast, I will give brainliest!
    12·2 answers
  • Question 5 pls this is due in 3 minutes!!
    15·2 answers
  • Question 1: Express the following out of scientific
    7·1 answer
  • When aqueous solutions of magnesium nitrate and sodium carbonate are mixed together what will happen
    11·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!