CART Thermochemistry and Energy

Question 1

What is the term for the heat released or absorbed during a chemical reaction at constant pressure?

Accepted Answer

Enthalpy change (ΔH)

Answer

Enthalpy change (ΔH) represents the heat flow in a reaction carried out at constant pressure.

Question 2

A reaction with a negative ΔH value is classified as:

Accepted Answer

Exothermic

Answer

A negative ΔH means the system releases heat to the surroundings, making the reaction exothermic.

Question 3

Which law states that the enthalpy of a reaction is the same whether it occurs in one step or multiple steps?

Accepted Answer

Hess's Law

Answer

Hess's Law states that total enthalpy change is path-independent and can be calculated by adding individual step enthalpies.

Question 4

The specific heat capacity of water is 4.18 J/(g·°C). How much heat is needed to raise 50 g of water by 10°C?

Accepted Answer

2090 J

Answer

Using q = mcΔT: q = 50 g × 4.18 J/(g·°C) × 10°C = 2090 J.

Question 5

Which of the following processes is endothermic?

Accepted Answer

Melting of ice

Answer

Melting requires heat input to break intermolecular forces, making it an endothermic process.

CART - Chemistry Acceleration Readiness Test Practice Test