Chemical Reactions Flashcards
physical change
change in appearance smell etc. change which does not result in a change in a chemical make up
chemical change
change that results in a change in a chemical make up or formula of starting chemicals
chemical reaction
process where original substances change into new substances with new properties
reactants
original substances or inputs of chemical reactions
products
new created substances or outputs of chemical reactions
CLUES that a chemical reaction has taken place
- gas is released 2. color change 3. heat change 4. precipitate formed
precipatate
a solid that is formed which cannot stay dissolved in a liquid.
ice cream melting example of
physical change
boiling water example of
physical change
dissolving something example of
physical change
biting a candy bar in 1/2 example of
physical change
burning leaves
chemical change
foods in stomach digesting
chemical change
Mix a solid with a liquid, solid disappears while temperature of liquid increases
it cannot be determined if a chemical reaction has taken place or not.
are new atoms formed in a chemical reaction
NO
chemical equations are used to represent the
reactants and products of a chemical reaction usually using the chemical formula but can use names too
equations are balanced to show
atoms are not created or destroyed in a reaction & that mass is conserved
to balance equations we add
coefficients to the front of molecules or atoms until we have an equal amount of each atom (and therefore mass) on both sides of the equation
we cannot change the subscripts to balance an equation because
this would change the chemicals that are in the reaction
combustion
when all substances in a compound combine with oxygen to form carbon dioxide and water
synthesis
2 or more substances combine to form 1 new more complex substance
decomposition
1 substance breaks down too form 2 or more simpler substances
single replacement
an uncombined element replaces an ion that is part of a composition
double replacement
two reactants are compounds- they simply switch like charged ions to form two new substances
how to identify a combustion equation
hydrocarbon `
acids
compounds that give rise to hydrogen ions when dissolved in water (H) NEGATIVE
acids are defined as
proton donors
bases
compounds that give rise to hydroxide when dissolved in water POSITIVE
bases are defined as
proton acceptors
neutralization reaction
a reaction between an acid & base
what happens during a neutralization reaction (2)
- negative ions of acid combine with the positive ions of the base to produce an ionic compound called a salt. 2. the hydrogen ion of the acid and the hydroxide ion of the base combine to form water
hydroxide
base
hydrogen
acid
mass is ____ in a balanced chemical equation
conserved
new chemicals are ____
created in a chemical reaction
the mass is always the
same
when determining how many atoms are present..
always distribute to everything even if there are no parentheses
fireworks are an example of
chemical change
the products of a combustion reaction always are
carbon dioxide and water
if the chemical formula is made up of one element
ion
if chemical formula is made up of more than 2 elements
there is a polyatomic ion involved in the formula
reaction rate
the rate at which reactants change to produce over time ; various things can be done to affect the reaction rate by affecting how quickly the reactant molecules come into contact with each other
concentration
the measure of the amount of a substance in a given unit of volume
higher concentrated chemicals will proceed at
a faster rate because there are more chances for reacting particles to come in contact
surface area
refers to how much of the material is exposed. breaking a solid into smaller particles will increase surface area
increased surface area will
increase the rate of reaction because it increases the exposure of reactants to eachother
temperature
the measure of energy of the particles
increased temperature will
increase the rate of reaction because faster moving reacting particles will come in contact sooner than slower moving particles
catalyst
a substance that increases the rate of reaction but itself is not changed by the reaction. it can be recovered after the reaction is over
a catalyst will
increase the rate of reaction by lowering the energy needed to allow the reaction to occur
stirring
A mixing of reactants
stirring will
increase the rate of reactants by increasing the exposure of reactions to one another
which law is violated when we don’t balance equations
the law of conservation of mass
grinding pepper
physical change
melting wax
Physical
During a chemical equation, whats taking place at the atomic level
the atoms of reactant chemicals rearrange to create different product chemicals
KNO2 is a
salt
HCN is a
acid
Fe(OH)2 is a
base
general products made when an acid and base are combined
a salt and water
Diatomic molecules always get a
2 subscript
formula for combustion
CO2 +H2O
