Oquizy

What type of reaction does this diagram represent?

Combustion only Endothermic Exothermic Reversible

Xinyi let 25 cm³ of 1.0 mol/dm³ HCl react with 25 cm³ of 1.0 mol/dm³ NaOH. She recorded the temperature rise = 6.5 °C.
Given water density is 1.0 g/cm³, find ΔH in kJ/mol.

–13.6 –27.2 –54.4 –6.5

1.2g of Mg reacts with excess HCl, releasing 6000 J. Find ΔH in kJ/mol.

–12 –120 –30 –60

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

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

Quiz: Chemistry - Chemical Energetics