| What is a reversible reaction | A reaction in which the product can react to re-form the original reactants |
| What is a equilibrium reaction | The products react together to re-form reactants at the same time as the reactants are forming products |
| What are the 4 Characteristics of equilibrium reaction | 1. It is dynamic
2. The forward and reverse reactions occure ar the same rate
3. Concentration of reactants and products remain constant at equilibium
4. Requires a closed system |
| What does the phrase dynamic equilivrium | the molecules or ions of reactants and products are continuously reacting |
| What does the position of equilibruim tell us | how far the reaction goes to the product or reactants |
| What happen's to the position of equilibrium when the concentration of product is greater than concentration of reactants? | The position of equilibrium is to the right (toward the product side). |
| Where is the position of equilibrium if the concentration of product is far less than the concentration of reactants | The position of equilibrium is to the left (towards the reactants side) |
| The position of equilibrium refers to what | the relative amounts of products and reactants present in an equilibrium mixture |
| What is Le Chatelier's principle | If one or more factors that affect a dynamic equilibrium is charged, the position of equilibrium moves to minimise this change |
| What happen's when the concentration of one or more of the reactants is increased? (3) | System is no longer in equilibrium
Position of equilibrium moves to the right to reduce the effect of the increase in concentration of reactants
Products are formed until equilibrium is restored |
| What happen's when the concentration of on eor more of the products is increased (3) | System is no longer in equilibrium
Position of equilibrium moves to the left to reduce the effect of the increase in concentration of product
More reactants are formed until equilibrium is restored |
| What causes pressure of a gas? | Molecules hitting the walls of the container |
| Decomposition of hydrogen iodide is an ...thermic reaction | Endothermic |
| When the temperature increases, the concentration of product increases. Position of equilibrium shifts to the right. How can we use Le Chateliers principle to explain this?(4) | 1. Increase in temperature increases the energy of surroundings
2. According to Le Chatelier's principle, the reaction will go in the direction that opposes the increase in energy
3. Reaction will go in the direction in which energy is absorbed, which is the endothermic reaction
4. Position of equilibrium shifts to the right |
| Increase of temperature favours an endothermic reaction, a decrease of temperature favours an exothermic reaction. This means that? (3) | 1. Decrease in temperature decreases the energy of the surroundings
2. According to Le Chateliers principle, the reaction will go in the direction that opposes the decrease in energy
3. Reaction will go in the direction in which energy is released, which is the exothermic reaction |
| What are the 5 key stages in equilibrium calculations | 1. Write the equation
2. Write information about the concentration given below each reactant/product
3 Deduce concentration at equilibrium
4. Write the equilibrium expression
5. Substitute the values to find Kc or the concentration of a particular reactant / product |
| What is partial pressure | Pressure exerted by any one gas in the mixture |
| How many Pa (Pascals) are in 1 atmosphere | 1 atmosphere = 1.01 x 10^5 Pa |
| The mole fraction of a gas is given by the relationship? | Number of moles of a particular gas ➗ total number of moles of all the gases in a mixture |
| What is the formula used to calculate partial pressure | mole fraction ✖️ total pressure (of all the gases in the mixture ) |
| Acids have what pH values | below pH 7 |
| Alkalis have what pH values | Above pH 7 |
| What is the pH value of a neutral solution | Exactly 7 |
| What reacts when A salt is formed. What is this type of reaction called | A salt is a compound formed when an acid reacts with a base. Type of reaction is called Neutralisation reaction |
| What is a base | A base is a compound that contains oxide or hydroxide ions and react with an acid to form a salt and water |
| What are Alkalis | Bases which are soluble in water |
| What is the Formula and the Ions formed in water for Hydrochloric acid | HCL
H⁺ + CL⁻ |
| What is the Formula and the Ions formed in water for Nitric acid | HNO₃
H⁺ + NO₃⁻ |
| What is the Formula and the Ions formed in water for Sulfuric acid | H₂SO₄
2H⁺ + SO₄ ²⁻ |
| What is the Formula and the Ions formed in water for Ethanoic acid | CH₃COOH
CH₃COO⁻ + H⁺ |
| What is an acid | substance that releases hydrogen ions when it dissolves in water |
| What are 3 common alkalis and their formulas | Sodium hydroxide (NaOH)
Potassium hydroxide (KOH)
Ammonia (NH₃) |
| What is a Bronsted-Lowry acid | A proton donor |
| What is a Bronsted-Lowry base | A proton acceptor |
| What are strong acids | Acids that dissociate almost completely in aqueous solution |
| What are weak acids | Acids that are only partially dissociated in solutions |
| What are strong bases | Bases that dissociate almost completely in solution |
| What group of metal hydroxides are strong bases | Group 1 |
| What are weak bases | Bases which dissociate to only a small extent in solutions |
| What are 2 methods we can use to determine pH | 1. Dipping a pH electrode into solution of the acid
2. Dipping universal indicator paper into a solution of acid and noting color change |
| Dilute solutions of a strong acids have greater electrical conductivity than those of weak acids of the same concentration. Why | because the concentration of hydrogen ions (and other ions) is greater in storng acids |
| What is an acid based indicator? | Dye or mixture of dyes that changes colour over specific pH range |
