AQA GCSE CHEMISTRY PAPER 1 EXAM. QUESTIONS WITH 100% CORRECT ANSWERS.

Why must the anode be replaced regularly? The anode must be replaced regularly because the oxygen produced at the anode reacts with the carbon in the graphite forming carbon dioxide gas What are exothermic reactions? Exothermic reactions are reactions that transfer energy to their surroundings What happens to the temperature of the surroundings in an exothermic reaction? In an exothermic reaction the temperature of the surroundings gets increases Give three examples of exothermic reactions Three examples of exothermic reactions are combustion, oxidation and neutralization What are two uses of exothermic reactions? Two uses of exothermic reactions are hand warmers and self-heating cans In an exothermic reaction what has more energy the reactants or the products? In an exothermic reaction the reactants have more energy that the products Why do the reactants have more energy that the products in an exothermic reaction? In an exothermic reaction the reactants have more energy that the products because energy is being transferred from the reaction to the surroundings What does the difference between the energy of the reactants and the energy the products tell us? The difference between the energy of the reactants and the energy the products tells us the energy that has been released to the surroundings What are endothermic reactions? Endothermic reactions are reactions that take in energy from their surroundings What happens to the temperature of the surroundings in an endothermic reaction? In an endothermic reaction the temperature of the surroundings decreases Give an example of endothermic reactions An example of a endothermic reaction is thermal decomposition What are two uses of endothermic reactions? Endothermic reaction are used in cold packs and cooking In an endothermic reaction what has more energy the reactants or the products? In an endothermic reaction the products have more energy that the reactants Why do the products have more energy that the reactants in an endothermic reaction? In an endothermic reaction the products have more energy that the reactants because energy has been taken in from the surroundings What does the difference between the energy of the reactants and the energy the products tell us? The difference between the energy of the reactants and the energy the products tell us the amount of energy taken in by the reaction What is needed for reaction to occur? Reactions can only occur when particles collide with each other with sufficient energy What is the activation energy? Activation energy is the minimum amount of energy that particles need in order to react In an exothermic reaction energy changes are shown as positive or negative? In an exothermic reaction energy changes are shown as negative Why are energy changes shown as negative in exothermic reactions? In an exothermic reaction energy changes are shown as negative because energy has been transferred In an endothermic reaction are energy changes shown as positive or negative? In an exothermic reaction energy changes are shown as positive Why are energy changes shown as positive in endothermic reactions? In an endothermic reaction energy changes are shown as positive because energy has been gained Is making bonds exothermic or endothermic? Making bonds releases energy so it is exothermic Is breaking bonds exothermic or endothermic? Breaking bonds requires energy so it is endothermic What is the energy value? The energy value tells us the energy required to break that bond How do you calculate the energy change of a reaction? To calculate the energy of a reaction you need two things the structure of the molecules and the energy value of each bond, add up the energy need to break all the reactants and the energy need to make all the products, the difference between the energy needed for the reactants and the energy needed for the products is the energy change What is an electrolyte? An electrolyte is a solution that can conduct electricity Give an example of an electrolyte An example of an electrolyte is an ionic compound What is one way of producing electricity? One way of producing electricity is to take two different metals and place them into an electrolyte What is the half equation for a negative electrode? 2H₂ → 4H⁺ + 4e⁻ What is the half equation for a positive electrode? O₂ + 4H⁺ + 4e⁻ → 2H₂O What is the overall equation? 2H₂ + O₂ → 2H₂O