Topic 9: Reversible Reactions Flashcards
What is a reversible reaction?
A chemical change that is able to go backwards and forwards.
To represent a chemical process we use….?
Half arrows (=)
Experiment 1: Reversible reaction of acids and bases (3rd form)?
Change color of Phenolpholein by adding a few drops of NaOH (aq) to change the solution -> pink, then changing it back by adding HCL (aq) -> colorless
Experiment 2: Reversible reaction, testing for water?
CuSO4. 5H2O(s) ->(heat) (H2O)<- CuSO4(s) 5H2O
Experiment 3: Reversible reaction, of states of matter 3rd form - diffusion?
NH4Cl(s)(white solid) ->(heat) (cool)<- NH3(g) + HCL(g) (colorless)
What is Chemical Equilibrium?
This is “When the rate of forward reaction equals the rate of the backwards reaction”, the reaction is said to be in equilibrium.
What is a dynamic Equilibrium?
The type of equilibrium that occurs in chemical reactions is called a dynamic equilibrium.
How is the position of a Equilibrium changed?
The position of a equilibrium can be changed by altering the concentrations of reactants or products, temperature or pressure.
How can the concentration change the position of the equilibrium?
A + B == C + D
- If more A is added the equilibrium moves to the right to reduce the concentration of A.
How can the temperature change the position of the equilibrium?
A + B == C + D = Heat
- When the forward reaction is exothermic, if the temperature is increased, the equilibrium moves to the left to get rid of extra heat.
How can the pressure change the position of the equilibrium?
A(g) + B(g) == C(g)
- If the pressure is increased the equilibrium will move to the side with the fewest number of gas molecules to reduce the pressure.
The Chemical equilibrium rule?
A chemical equilibrium will move to counteract any change imposed on it.
Equation for the Bromine water experiment?
Br2(aq) +H2O(l) (yellow) == Br(aq) + OBr(aq) +H+(aq) (colorless)
Ammonia to ammonia chloride reaction?
ammonia (NH3(g)) + hydrogen chloride (HCL(g)) == ammonium chloride (NH4Cl(s).
Properties of Ammonia? NH3
- Colorless
- Colorless gas
- Vary soluble in water
- Pungent smell
- Gas at room temperature
- Base produces a solution of PH 10-11 when dissolved in water.
Ammonia is needed and the starting material for which products?
Nitric acid and ammonia nitrate (a fertilizer)