Enthalpy and Heat of Formation

The video tutorial explains stoichiometric proportions and the concept of heat of reaction. It provides examples of reactions, such as calcium carbide with water and C2H4 with oxygen, to illustrate enthalpy calculations. The tutorial also discusses the importance of temperature and reaction completion in determining enthalpy changes.

What is the enthalpy change when solid calcium carbide reacts with water to form calcium hydroxide and acetylene?

• 226.75 kJ/mol

• -62.76 kJ/mol

• -285.84 kJ/mol

• -125.4 kJ/mol

Which of the following is the heat of formation for gaseous acetylene?

• -62.76 kJ/mol

• -285.84 kJ/mol

• 226.75 kJ/mol

• -986.59 kJ/mol

What is the first step in calculating the enthalpy change using heats of formation?

• Multiply the enthalpy of reactants by products

• Add the enthalpy of reactants and products

• Subtract the enthalpy of reactants from products

• Divide the enthalpy of products by reactants

What is the heat of formation for calcium carbide?

• 226.75 kJ/mol

• -62.76 kJ/mol

• -285.84 kJ/mol

• -986.59 kJ/mol

Why is it important to have 100% conversion in enthalpy calculations?

• To ensure the reaction is at equilibrium

• To maintain consistent temperature conditions

• To accurately calculate the enthalpy change

• To prevent side reactions

In the reaction of ethylene with oxygen, what is the coefficient of CO2 in the balanced equation?

• 5

• 4

• 2

• 3

What is the delta H of reaction for ethylene reacting with oxygen?

• -2878 kJ/mol

• -62.76 kJ/mol

• 226.75 kJ/mol

• -125.4 kJ/mol

How do you calculate the delta H for a reaction if the products are formed at a different temperature?

• Use the standard delta H of reaction

• Use the average temperature

• Use the mcpΔT calculation

• Ignore the temperature difference

If the reaction does not go to completion, what must be considered in the enthalpy calculation?

• The stoichiometric coefficients

• The temperature of products

• The mass of reactants

• The impurities present

What calculation is necessary if the reactants and products are not at the same temperature?

• Use the average temperature

• Ignore the temperature difference

• Use an mcpΔT calculation

• Use the standard delta H of reaction