exam semester 1 Flashcards
what are spontaneous chemical reactions
reactions that occur at room temperature without the impact of energy such as heat or electricity
-occur at room temp
some quick, some slow
whar are energy transformations
evident in changes in the temperature of surrondings and/or the emission of light
chemical reactions
involce the creation of new substances and associated energy transformations
what are some chemical equations
acid + sulphides —-> salt + hydrogen sulfide
acid + sulphite —–> salt + water + sulfur dioxide
water + active metal —-> salt + hydrogen
base + ammonium salt ——> salt + water + ammonia
base + non-metal oxide —–> salt + water
what is a precpitation reaction
reaction when solid formed
what are net ionic equations
Spectator ions are those ions that appear exactly the same on each side of the ionic equation.
dont effect the reaction
what is moler mass
mass in grams of 1 mole of sustance take the atomic mass of the element of the periodic table and multiply it by the amount of times it occure in the equation top m left n right mr
what is a mole
a counting unit
where did the mole come from
the number of atoms in exactly 12g of carbon-12 isotope
the number of particles in one mole, 6.022 x 10^23, is known as auogadros constant or number
what is the atomic mass
mass in grams of one mole of atoms in an element
what is number of particles
refers to many things - atoms, ionic unit, or molecules - dependant on the substance
formula: n=#p/na
n=moles
na = auogadros constant
what is stoichiometry
measures these quantitative relationships, and is used to determine the amount of products/reactants that are produced/needed in a given reaction.
what must happen for a chemical reaction to occur
the bonds between the atoms in the reactants must be broken and new bonds between the atoms in the product must be formed
what happens in an exothermic reaction
releases heat energy to the surrondings
the temperature of the surrondings increases
the energy released from forming new bonds is greater than the energy needed to break old bonds
(triangle) H is negative
what happens in an endothermic reaction
takes in heat from surrondings
the temperature of the surrondings decreases
the energy needed to break old bonds is greater than the energy released from forming new bonds
(triangle) H s positive
what requirements must be met before a chemical reaction will occur
the reacting particles must collide
they must collide with a specifc minimum amount of energy, called the activation energy
the particles must collide with a favourable orientation
what is a succesful collision
has suffiecient energy and an appropiate orientation to allow old bonds to be broken and new bonds to be formed. this leads to the formation of products
what is an unsuccesful collision
the energy and or orientation are not satisfactory. this doesnt lead to the formation of products
what is the activated complex/transition state
a temporary, highly unstable structure that has more energy then either the reactants or products. it is the stage of maxium potential energy
what is the activation energy
the miniumum amount of energy required for a reaction to occur
what is enthalpy
the total energy possesed by a chemical substance
what is an energy profile diagram
shows the enthalpy of the reactants, activated complex and products
the number of successful collisons depends on
total number of collisions
percentage of collisions that are succesful
what happens if the reactants only require a small amount of energy
the activation energy will be low
how can you speed up the rate of reaction
increasing temperature, increasing surface area, increasing pressure, increasing concentration, adding a catalyst
what happens when you increase the concentration in a reaction
the number of particles per unit increases
this increases the number of collisons, therefore increasing the number of succesful collisions and therefore increasing the rate of reaction
what happens when you increase the pressure in a reaction
by increasing the pressure, the particles per unit volume increases
this increases the number of collisons, therefore increasing the number of succesful collisions and therefore increasing the rate of reaction
what happens when you increase the surface area in a reaction
more of the solid is exposed and therefore more collsions are possible.
this increases the number of collisons, therefore increasing the number of succesful collisions and therefore increasing the rate of reaction
what happens when you increase the temperature in the rate of reaction
the average kinetic energy of the particles is increased. therefore a greater proportion of particles have the minimum amount of energy to react and therefore increasing the rate of reaction
what happens when you add a catlayst to a reaction
isnt used up in the reaction but is able to increase the rate of chemical reaction
it provides an alternate pathway with lower activation energy meaning a greater proportion of the particles have the required energy to react
