4U CHEM EXAM (MC)

The minimum amount of energy required to overcome the energy barrier in a chem rxn is…

Activation energy.

An active complex is a chemical species that is…

Unstable and has high P.E.

The presence of a catalyst is thought to increase the rate of reaction by…

Decreasing the activation energy of the rxn.

Ineffective collisions are collisions that involve particles…

That rebound from the collisions unchanged.

If a rxn can be broken down into a rxn mechanism, then the steps of the rxn are known as…

Elementary steps.

The number of particles that usually collide in an elementary step are…

1-2

Kinetic Energy is…

The energy of motion.

Enthalpy is an expression for…

Energy content.

Tempurature means…

The average kinetic energy of molecules.

Specific heat capacity means…

The heat required to raise the tempurature of 1 gram by 1C.

What physical state or nitrogen has the highest entropy?

Gas.

A chemical system in which neither matter nor energy can flow into or out of the system is described as…

An isolated system.

What is the best observable evidence that equilibrium has been established?

Macroscopic properties appear to be constant.

A system comes to equilibrium. What do we know for sure?

Rate of forward rxn = rate of reverse rxn.

If the equilibrium constant is increased by temp change, concentrations of ____ will…

Products increase and reactants decrease.

The equilibrium constant can be changed by…

Changing the tempurature.

Adding a catalyst to equilibrium while keeping temp constant will….

Increase the rate of both forward and reverse rxns.

What releases hydrogen ions in aqueous solutions?

An Arrhenius acid

Brønsted-Lowry-Lowry says that an acid is a substance that can…

Donate protons while in solutions.

The conjugate base of a weak acid is a….

Weak base.

A buffer solution will…

Resist large changes in pH when a strong acid or base is added.

An orbital is best described as…

A figure that indicates where one would find electrons 95% of the time.

Intermolecular forces are…

Attractive forces between 2 covalent molecules.

Potassium chloride dissolved in pure water is an example of…

An ionic compound dissolved in polar solution.

The main attractive forces between most polar molecules is…

Dipole-dipole

A good solvent for polar molecules like HCL is…

Water

Metals are generally better conductors than non metals because…

Valence electrons in metals are more mobile.

Water has a higher boiling point than hydrogen sulphide because…

Water has stronger intermolecular attractions