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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

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3 years ago
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xenn [34]
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4 0
3 years ago
How are Parkinson's disease and ALS similar?
Diano4ka-milaya [45]

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Explanation:

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This is why the third option is the correct one.

4 0
3 years ago
.) Neon and HF have approximately the same molecular masses. a.)Explain why the boiling points of Neon and HF differ b.)Compare
lisov135 [29]

Answer:

See explanation

Explanation:

a) The magnitude of intermolecular forces in compounds affects the boiling points of the compound. Neon has London dispersion forces as the only intermolecular forces operating in the substance while HF has dipole dipole interaction and strong hydrogen bonds operating in the molecule hence HF exhibits a much higher boiling point than Ne though they have similar molecular masses.

b) The boiling points of the halogen halides are much higher than that of the noble gases because the halogen halides have much higher molecular masses and stronger intermolecular forces between molecules compared to the noble gases.

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4 0
3 years ago
T or F: The mass of an atom is so small it is rounded to 0 amu
klemol [59]

Answer: true

Explanation:

4 0
3 years ago
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