Chpt. 10, Chemical Reactions Flashcards
indicators of a chemical reaction
the process spontaneously gives off heat (is exothermic) or spontaneously gets cold (is endothermic)
bubbles are spontaneously given off (like in vinegar and baking soda)
there may be a color change
the chemical properties are changed (like when you burn wood and it turns into ashes)
a precipitate is formed
indicators of a physical process
temperature change or bubbles will occur only if you do something specifically to make them happen
probably not a color change
chemical properties don’t change, and a precipitate does not form
definition of a chemical equation
a complete list of the reactants (or reagents) and products of a reaction
exothermic reaction
a reaction that releases more energy that it takes in; to indicate that a reaction is exothermic, “triangleH = +” is written after the reaction
endothermic reaction
a reaction that requires more energy than it releases; to indicate that a reaction is endothermic, “triangleH = -“ is written after the reaction
reactants/reagents
what you start with in a chemical reaction
products
what you end up with in a chemical reaction
conditions of a chemical reaction
these are things that are necessary in order for a chemical reaction to occur; when chemical reactions are written out, the reagents and products are connected by an arrow, and conditions of the reaction are placed over the arrow; they can be pretty much anything
when heat is required for the reaction, a triangle is placed over the arrow; when a specific temperature is required, that temperature is placed over the arrow; when cooling is required, a triangle followed by a “-“ sign is placed over the arrow
state of matter indication
after every element or compound included in a reaction, the state of matter must be indicated; this is done with a one-letter subscript in parenthesis directly following the element or compound; the symbols are as follows:
(g) = gas
(l) = liquid
(s) = solid
(s) = solute (dissolved in water; not technically a state, but included)
balancing equations
Because reactions begin and end with the same number of atoms, the elements and compounds must be added in specific ratios. These ratios can be found by balancing chemical equations, which is the process of logically trying different values until the correct ratio for a given reaction is found.
the 6 types of chemical reactions
synthesis reaction decomposition reaction combustion reaction single displacement reaction double displacement reaction acid-base reaction
determining reaction type
- Does something containing C and H react with 02? If yes, it’s a combustion reaction.
- Do simple compounds make a complicated one? If yes, it’s a synthesis reaction.
- Does a complicated compound break down to make simpler ones? If yes, it’s a decomposition reaction.
- Are there any pure elements in the reaction? If yes, it’s a single displacement reaction.
- Is water formed in the reaction? If yes, it’s an acid-base reaction. If no, it’s a double displacement reaction.
synthesis reactions
occur when 2 chemicals combine to form 1 larger chemical
decomposition reactions
occurs when one chemical breaks down to form to or more smaller chemicals
combustion reactions
when something organic (something containing both hydrogen and carbon atoms) reacts with oxygen to form carbon dioxide gas and water vapor (plus lots of energy)
