chemistry paper 1

Created by

anaya

Cards (248)

What is an acid? An acid is a substance that forms aqueous solutions with a pH of less than 7. Acids form H+ ions in water.
What is a base? A base is a substance greater than a pH of 7
What is a pH scale? A pH scale is a measure of how acidic or alkaline a solution is
What is the reaction between an acid and alkali called? Neutralisation reaction: Acid + Base --> Salt + Water
What is an alkali? An alkali is a base that dissolves in water to form a solution with a pH greater than 7. Alkalis form OH- ions in water.
What is a strong acid? A strong acid is an acid that is completely ionised in aqueous solution
What is a weak acid? A weak acid is partially ionised in aqueous solution
What is reduction? Reduction is the gain of electrons or loss of oxygen
What is oxidation? Oxidation is the loss of electrons and gain of oxygen
Reactivity Series:
What is a displacement reaction? When a more reactive metal can displace a less reactive metal from a compound
Name a strong acid Hydrochloric acid, nitric acid, sulfuric acid
What is a titration used for? If the volumes of 2 solutions that react completely are known and the concentration of 1 solution is known, the concentration of the other solution can be calculated.
What is a pipette used for? To measure a fixed volume accurately
What is a burette used for? To measure a variable/continuous volume
Steps of a titration - alkali in burette - acid in a conical flask measured out with 25cm^3 - add a few drops of indicator - add alkali to acid until colour changes - swirl conical flask - add alkali drop wise towards the end - note final burette reading - repeat for accurate results
What type of indicator is used in a titration? A single indicator because it has a sudden colour change (end-point)
Name an indicator suitable for a titration Methyl orange (yellow in alkalis and red in acids)
What happens when an acid reacts with a metal oxide/hydroxide? Acid + Metal Oxide/Hydroxide ---> Salt + Water
Metal carbonates and metal hydroxides are examples of Bases
____ + __ __ ---> Salt + Water + Carbon Dioxide Acid + Metal Carbonate
What do metals form? Positive ions, they lose electrons. All elements in the reactivity series form positive ions.
What happens when an acid reacts with a metal? Acid + Metal ---> Salt + Hydrogen
How can you form a metal hydroxide and hydrogen gas? Metal + Water ---> Metal Hydroxide + Hydrogen
How are metals above carbon in the reactivity series extracted? By electrolysis or by displacement reactions with more reactive metals
How are metals that are less reactive than carbon extracted? By reduction with carbon
What is a reaction that separates a metal from its oxide called? A reaction that separates a metal from its oxide is called a reduction reaction
What is produced at the anode? At the anode, if the element contains chlorine/bromine/iodine (also known as halide ions) than that is formed. Else, oxygen will be formed.
What is the negative electrode? Cathode
What is activation energy? Activation energy is the amount of energy required to start a chemical reaction
What is an endothermic reaction? An endothermic reaction is a reaction where energy is drawn in from the surroundings, causing the surroundings and object to cool down.
What is an exothermic reaction? An exothermic reaction is a reaction which cools itself down, giving heat to the surroundings.
What elements form at the cathode? If the element is less reactive than hydrogen in the reactivity series, the metal will form. Otherwise, hydrogen will be produced at the cathode.
Name 2 different types of reactions which are exothermic - Neutralisation - Combustion
What type of process is the breaking of existing bonds? Endothermic
What type of process is the forming of new bonds? Exothermic
In exothermic reactions the energy released by forming bonds is ____ than the energy used to break them. greater
Bond Energy Formula energy change = sum of the energy needed to break bonds (reactants) - energy released when new bonds are formed (products)
What is a reaction profile diagram? Reaction profiles are diagrams that show the energies of the reactants and products in a reaction and how they change over the course of the reaction.
Example of a endothermic reaction citric acid + sodium hydrogencarbonate