Chemical Reactions

The change can usually be reversed by simple physical methods

No new substances are formed during the process

The total mass of the products is less than the mass of the reactants

New substances are formed with different properties from the reactants

They break down into hydrogen and oxygen atoms

They gain kinetic energy and move further apart

They form new covalent bonds with each other

They lose mass as they turn into a gas

The mixture changes from a solid to a liquid state upon heating

A substance dissolves completely in a solvent

A precipitate (solid) forms and there is a significant temperature rise

The total volume of the mixture is equal to the sum of the individual volumes

Particles become larger and collide more often.

The frequency of collisions decreases as particles move away from each other.

Particles gain kinetic energy, leading to more frequent and more energetic collisions.

The particles lose energy to the surroundings, slowing down the reaction.

The particles move with a higher average speed.

The activation energy of the reaction is reduced.

There are more reactant particles per unit volume, leading to more frequent collisions.

The total energy of the system decreases.

To increase the yield of the products by shifting equilibrium.

To be consumed in the reaction to provide energy.

To provide an alternative reaction pathway with a lower activation energy.

To increase the temperature of the reaction mixture.

The reaction must be in a closed system

The temperature must be $0^{\circ}C$

The reaction must involve only gases

The pressure must be high

It increases the yield of the products

It speeds up both the forward and reverse reactions equally

It shifts the equilibrium position to the right

It increases the activation energy of the reverse reaction

The concentration of products is equal to the concentration of reactants

The reaction has stopped completely

The rate of the forward reaction equals the rate of the reverse reaction

The mass of the reactants is decreasing

The gas becomes a darker brown.

The gas becomes completely colorless.

The color changes from brown to blue.

No change in color is observed.

The yield stays the same.

The yield increases as the equilibrium shifts to the right.

The yield decreases as the equilibrium shifts to the left.

The yield increases because the particles move faster.

It shifts the equilibrium to the right to produce more $SO_{3}$.

It shifts the equilibrium to the left to produce more $SO_{2}$.

It has no effect on the position of the equilibrium.

It increases the yield of $SO_{3}$ by increasing the pressure.

Oxidation

Reduction

Neutralization

Precipitation

+2

+4

-2

+7

$CuO$

$Cu$

$H_2$

$H_2O$