Hess's Law Reaction Manipulation

Melissa Maribel guides students through a Hess's Law problem, demonstrating how to manipulate and adjust reactions to find the enthalpy change of a target reaction. The tutorial covers flipping reactions, adjusting coefficients, and adding reactions together to achieve the desired outcome. The video concludes with a summary and additional resources for further learning.

What is the main goal when manipulating the reactions in this Hess's Law problem?

• To manipulate the bottom reactions to match the top reaction.

• To eliminate all reactants.

• To find the enthalpy change of the bottom reactions.

• To make all reactants and products equal.

What must be done to the enthalpy change when a reaction is flipped?

• Multiply by 2

• Multiply by -1

• Add 1

• Divide by 2

How do you adjust the quantity of NH3 in the reaction?

• Multiply the reaction by 2

• Add more NH3

• Multiply the reaction by 1/2 and flip it

• Remove NH3

What is the purpose of multiplying the entire reaction by 1/2 when dealing with HCN?

• To eliminate HCN

• To change the side of HCN

• To decrease the number of HCN molecules

• To increase the number of HCN molecules

Why is it unnecessary to change the reactions involving H2?

• H2 is not present in the reactions

• H2 is already balanced

• H2 appears in every reaction

• H2 is not needed in the final reaction

What is the common denominator used when adding fractions of H2?

• 3

• 2

• 1

• 4

What is the final step after achieving the goal reaction?

• Add more reactants

• Flip all reactions again

• Cancel out like terms and calculate total enthalpy change

• Multiply all reactions by 2

What happens to the carbons in the final reaction?

• They are flipped to the reactant side

• They are doubled

• They are canceled out

• They are added to the product side

What is the result of subtracting 1/2 from 7/2 in the context of H2?

• 3

• 4

• 5

• 6

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