Q: Which formula is used to calculate the heat absorbed by water in a calorimeter?

$$q = m \times C \times \Delta T$$

Question 1

Which of the following best describes the First Law of Thermodynamics?

Accepted Answer

Energy can be converted from one form to another, but it is neither created nor destroyed.

Question 2

A chemical reaction occurs in a closed system. Which of the following statements is true?

Accepted Answer

The system can exchange heat but not mass with its surroundings.

Question 3

Which equation correctly represents the relationship between internal energy, heat, and work?

Accepted Answer

$$\Delta E = q + w$$

Question 4

A battery is discharged by running a fan. Which of the following is a state function?

Accepted Answer

The change in internal energy ($$\Delta E)$$

Question 5

Which process is endothermic?

Accepted Answer

Heat flows from the surroundings into the system.

Question 6

What is the correct sign convention for work done BY the system on the surroundings?

Accepted Answer

Work is negative ($$w \u003c 0)$$

Question 7

Which of the following is NOT a state function?

Accepted Answer

Heat ($$q)$$

Question 8

A reaction occurs at constant pressure and only pressure–volume work is done. Which thermodynamic quantity equals the heat flow?

Accepted Answer

Enthalpy ($$\Delta H)$$

Question 9

Which equation defines enthalpy?

Accepted Answer

$$H = E + PV$$

Question 10

Which statement about enthalpy is correct?

Accepted Answer

Enthalpy depends on the states (phases) of reactants and products.

Question 11

A reaction in a bomb calorimeter measures which thermodynamic quantity?

Accepted Answer

Change in internal energy ($$\Delta E)$$

Question 12

Which formula is used to calculate the heat absorbed by water in a calorimeter?

Accepted Answer

$$q = m 	imes C 	imes \Delta T$$

Question 13

Which statement about Hess’s Law is correct?

Accepted Answer

The enthalpy change for a reaction is the sum of the enthalpy changes for individual steps.

Question 14

Which of the following is true about the standard enthalpy of formation ($$\Delta H^\circ_f) $$for an element in its standard state?

Accepted Answer

It is zero by definition.

Question 15

Which bond has the highest average bond enthalpy according to the provided table?

Accepted Answer

C=O double bond

Question 16

Which of the following statements about bond enthalpy is correct?

Accepted Answer

Bond enthalpy is always positive because energy is required to break bonds.

Question 17

A reaction involves breaking 2 moles of H–H bonds and forming 2 moles of O–H bonds. Using the bond enthalpies $$H–H = 436 kJ/$$mol and $$O–H = 463 kJ/$$mol, estimate the enthalpy change for the reaction.

Accepted Answer

$$2 	imes 463 - 2 	imes 436 = 54 kJ$

Question 18

Which scenario best illustrates an exothermic reaction?

Accepted Answer

Combustion of gasoline in a car engine, releasing heat to the surroundings.

Question 19

Which of the following is an extensive property?

Accepted Answer

Enthalpy

Question 20

If a system absorbs 100 J of heat from the surroundings and does 40 J of work on the surroundings, what is the change in internal energy ($$\Delta E$$)?

Accepted Answer

$$\Delta E = 100 - 40 = 60 J$$

Chapter 5: Thermochemistry – Study Notes

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