CHEM TEST 2 Flashcards
what is a physical change
a change that does not create a new substance. e.g ice to water
what is a chemical change
when a new substance with a diffrent formula is created. e.g burning anything
what does (aq) mean
aqueous meaning dissloved in water
what is the diffrence between an exothermic and endothermic reaction
Exothermic means that it produces heat, endothermic means that it sucks in heat
what is combustion and its general form
combustion is any reaction where a substance burns in oxygen to produce light and heat.
fuel+oxygen - carbon dioxide+water
respiration , and its general form
a chemical reaction that goes into cells of all living things
glucose+oxygen gas - carbon dioxide+water
corrosion, general form
When metals combine with oxygen gas in the air to from metal oxides
metal+oxygen gas - metal oxide
decomposition, general form
when a single reactant breaks apart to form several products
XY - X+Y
combination, general form
when to reactants combine to form a single product
X+Y - XY
percipitation, general form
when 2 clear sloutions are mixed together they react to form an insoluable solid
salt (aq) + salt (aq) - solid+ salt (aq)
neutralisation, general form
when an acid reacts with a base
acid+base - salt + water
acid and metal, general form
when acids react with metals
acid+metal - salt+hydrogen gas
MASH
acid & carbonate, general form
when acids react with carbonates
acid+carbonate - salt+water+carbon dioxide
CWA
define solid, what happens when temp is increased
particles are close together vibrating. as temp increases particle speed and energy increases until melting point is reached and the bonds break to form a liquid
define liquid, what happens when temp is increased
particels that are close togther but moving over each other. as temp increases so does spped and energy until bonds break and a gas is formed
define gas, what happens when temp is increased
particles are individual and far apart moving rapidly in all directions. as temp increases speed/energy increases
how do you calculate reaction rate
change in product
time
change in reactants
time
what are the two conditions of collison theory
- energy of the collision must be big enough to break bonds
- bonds must have the correct orientation
how does temp affect reaction rate , draw diagram
low temp: the particles move too slowly with low energy. this results in most collisions being unsuccessful
high temp:th eparticel sar emoving faster with more energy. this results in more succsessful collisions ( but not all due to wrong orientations)
how does concentration affect reaction rate, draw
low concentration: a low number of successful collision as it is unlikley that the particles will collide. this means a low reactino rate
high concentration: lots more successful collisions ( same % of successful collisions as low concentration). this means faster reaction rate
how does a successful collision occour
when particels have enough energy and the correct orientation.
how does surface area affect reaction rate, draw
low surface are: means less area for a solution to react with, low number of particles on the outside of a solid or liquid so low number of collisions and successful collisions. this means low reaction rate
high surface area: more surface area is exposed so more collisions can occour. still the same % of successful collisions as low surface area. this means faster reaction rate
what is the law of conservation of mass
matter cannot be created or destroyed but it can change form
