Hess law can help us to obtain the enthalpy of a series of reactions by summation. The missing enthalpy of this reaction is −198kJ.
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What is Hess law?</h3>
According to the Hess law of constant heat summation, the enthalpy of a sequence of reactions can be obtained as the sum of the enthalpies of all the reactions.
Now looking at all the reavtion written here in order to obtain the missing enthalpy, we conclude that the missing enthalpy is −198kJ.
Learn more about enthalpy: brainly.com/question/3393755
Answer:- 3.12 g carbon tetrachloride are needed.
Solution:- The balanced equation is:

From given actual yield and percent yield we will calculate the theoretical yield that would be further used to calculate the grams of carbon tetrachloride.
percent yield formula is:
percent yield = 


theoretical = 3.44 g
From balanced equation, there is 2:1 mol ratio between dichloethane and carbon tetrachloride.
Molar mass of dichloroethane is 84.93 gram per mol and molar mass of carbon tetrachloride is 153.82 gram per mol.

= 
So, 3.12 grams of carbon tetrachloride are needed to be reacted.
Answer:
b. 6.02 x 1023 molecules
Explanation:
The formula mass of ammonia is 14 + 1 × 3 = 17.
The number of moles in 27.6g ammonia is 27.6 ÷ 17 = 1.62 mol.
A mole is 6.02 × 10²³, so the number of hydrogen atoms in a 1.62 moles of ammonia is 1.62 × 6.02 × 10²³ × 3 = 2.93 × 10² atoms.
Answer:
2. Na2O
Reasoning:
Na (soduim) is the only metal out of all the elements in the answer choices, and is bonded with oxygen, a nonmetal, therefore creating an ionic bond.