Unit E Chem Test
List the 3 evidences of a chemical reaction.
1. formation of a precipitate 2. change in energy 3. evolution of a gas
What gases are always written as diatomic molecules?
H, N, O, F, Cl, Br, I
What states that if a system at equilibrium is subjected to a stress, the equilibrium will be displaced in such a direction as to relieve that stress?
Le Chatelier's principle
What does sulfer always look like as a gas?
S₈
What is a positive test for hydrogen?
a burning splint pops
What is the minimum energy required to start a reaction?
activation energy
What replaces what on the reactivity series?
an element replaces any element below it on the list
If the concentration of a substance is increased, equilibrium shifts ______ the substance that is increased.
away from
What is a substance that increases the rate of a reaction without being consumed in the process?
catalyst
What occurs when the rate of a forward and reverse chemical reactions are equal?
chemical equilibrium
What are used to indicate the number of molecules in a chemical formula?
coefficients
In what type of reaction do atoms or ions from two different compounds replace each other forming a product that leaves the reaction environment?
double replacement
What type of reaction: compound + compound ---> compound + compound
double replacement
Rate ___ for each 10 degrees C increase in temperature.
doubles
Energy is absorbed in a ______ reaction.
endothermic
If surrounding get colder?
endothermic
If (triangle)H= +
endothermic reaction, added to reactants
Energy is released in a _______ reaction.
exothermic
If surroundings get warmer?
exothermic
If (triangle)H = -
exothermic reaction, added to products
The fewer the bonds to be broken, the ____ the rate.
faster
The weaker the bonds to be broken, the _____ the rate.
faster
If the activation energy is high, ___ collisions have enough energy to form the activated complex.
few
What does (g) stand for?
gas
In what type of reaction is a hydrocarbon burned in the presence of oxygen forming carbon dioxide and water?
hydrocarbon combustion
What type of reaction: hydrocarbon + oxygen ---> carbon dioxide + water vapor
hydrocarbon combustion
What does (aq) stand for?
in a solution of water
Increasing the concentration of one or more reactions, ____ the rate of reaction.
increases
Increasing the pressure on a gas, ______ the reaction rate.
increases
Increasing the surface area of solid reactants, _____ the rate of reaction.
increases
Temperature usually ____ the rate of a reaction.
increases
Reactions involving ions are usually _____.
instantaneous
The ___ the interval between the elements, the more vigorous the reaction.
larger
What does (l) stand for?
liquid
If the activation energy is low, ___ collisions have enough energy to form the activated complex.
more
What are 7 factors that affect reaction rates?
nature of reactants, surface area, concentration, temperature, pressure, activation energy, and catalyst
What are graphs that show the change of energy in a reaction?
potential energy diagrams
What 3 things can double replacement reaction form?
precipitate, gas, or water
2 of the most common stresses that affect a system are?
pressure and temperature
In what type of reaction do two or more reactants come together to form a single product?
simple composition
What type of reaction: element + element ---> compound
simple composition
What are the six types of chemical reactions?
simple composition, simple decomposition, single replacement, double replacement, hydrocarbon combustion, and other
In what type of reaction does a single compound broken down into 2 or more smaller compounds or elements?
simple decomposition
What type of reaction: compound ---> element/compound + element/compound
simple decomposition
In what type of reaction does an uncombined element replace an element that is part of a compound?
single replacement
What type of reaction: element + compound ---> element + compound
single replacement
Reactions for molecules are usually ___ than those of ions.
slower
What does (cr) stand for?
solid
What does (s) stand for?
solid
What are used to indicate the number of atoms in a chemical formula?
subscripts
What do catalysts lower?
the activation energy
If the concentration of a substance is decreased, equilibrium shifts ______ the substance that is decreased.
toward
