Oquizy

Which is true about the catalyst?

Changes ΔH Increases energy of products Lowers activation energy of the reaction Provides a pathway with lower activation energy

Which statement correctly defines enthalpy change (ΔH)?

The change in energy of bonds only The energy needed to start a reaction The heat change at constant pressure The temperature change of the surroundings

Why is a polystyrene cup used in calorimetry experiments?

To absorb extra heat To allow faster mixing To cool the solution To minimise heat loss to the surroundings

Hydrogen gas reacts with chlorine gas to form hydrogen chloride according to the following equation: H₂ + Cl₂ → 2HCl. The bond energies of the relevant bonds are:
- H–H = 436 kJ/mol
- Cl–Cl = 243 kJ/mol
- H–Cl = 431 kJ/mol.
What is the overall enthalpy change?

+179 kJ/mol +272 kJ/mol –183 kJ/mol –430 kJ/mol

A student heats 50.0 g of water from 20 °C to 30 °C. Given c = 4.18 J/g°C for water.
What is the energy absorbed? What is the energy absorbed?

209 J 2090 J 4180 J 50 J

Which is most reactive based on energy released?

Fe Mg Same Zn

Quiz: Chemistry - Chemical Energetics