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Chemical Reactions
Definitionsn and Important Questions
| Question | Answer |
|---|---|
| physical change definition + characteristic | process in which no new substance is created+ usually not easy to reverse |
| examples of physical change | jelly setting in freezer, grating cheese, haircut, chopping inion, mixtures |
| exothermic process definition | a process in which heat is given out to surrounding |
| why do you produce sweat (in exothermic context) | if water evaporates on your body, it takes heat from body to change from liquid to gas. sweat uis produced for this reason- to cool you down. |
| exothermic process example | water turning into ice: because the water loses heat to be able to turn into a solid |
| exothermic or endothermic: icicles melting | Endothermic: is takes in heat from surroundings in order to melt |
| exothermic or endothermic: burning candle | exo |
| exothermic or endothermic: animal respiring | exothermic: when respiration energy is released into body!! |
| exothermic or endothermic: plants photosynthesising | Photosynthesis is an endothermic reaction because in order for it to occur, the plants in which it occurs must absorb energy |
| exothermic or endothermic: rusting iron | exothermic : heat is released |
| chemical reactions definition | a process that involves rearrangement of the molecular or ionic structure of a substance, as distinct from a change in physical form or a nuclear reaction. |
| three chemical indications | -gas produced -colour change / cloudiness occurs -heat, sound, electricity produced |
| chemical reaction characteristics x3 | -new substance formed (iron+air=iron oxide) -usually cannot be reversed (cake baking) -involves an energy change (firework) |
| why do glowsticks glow? | when you first bend a glowstick, it releases a chemical from an inner capsule. this reacts with the other chemicals and causes the fluorescent dye to glow |
| chemical reaction examples | egg making, cake baking, rusting, food digestion, when muscle cells release energy from digested food, firework |
| rusting experiment: conditions necessary for rusting | -water and oxygen must be present for rusting to occur |
| rusting experiment: what should you do to the water before? | boil it and cool. boiling it removes any oxygen dissolved in it |
| rusting experiment: why put oil ontop of water | stops oxygen getting into water |
| rusting experiment: what chemical should be used for the contol? | calcium chloride: removes moisture from air |
| reactants def | reactants are the substances present before the chemical change takes place |
| products def | the products of a substance that are formed by the end of the chemical reaction |
| vinegar+ baking soda = ? | co2 + sodium acetate + water |
| photosynthesis equation | carbon dioxide + water= glucose + oxygen |
| respiration equation | glucose + oxygen= carbon dioxide + water |
| equation for when you light gas on a gas cooker | methane+ oxygen = carbon dioxide + water vapour |
| Law of Conservation of Mass | states that matter cannot be created or destroyed, but can only be changed from one form to another |
| what can we conclude from the law of conservation of mass? | total mass of reactants= equal to the mass of the products |
| Activation energy | is the minimum amount of energy needed to start a chemical energy |
| expale of activation energy | hydrogen and oxygen mixed at room temperature will not create any new substance unless it is under a slame |
| reaction rates | the speed of a reaction |
| what cause chemical reactions? | molecules and atoms colliding |
| how is the particles present in the reactants affecting the reaction rate | the more molecules of the reactants there are the more often the molecules will collide. the more energy the molecules have, the harder the collisions will be |
Created by:
grishmakandel12
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