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70 terms

Chemical Reactions

STUDY
PLAY
What law must chemical equations obey, making them balanced?
the Law of Conservation of Matter
What are the five types of reactions?
synthesis, decomposition, single replacement, double replacement, and combustion
What are the diatomic molecules?
Hydrogen, Nitrogen, Oxygen, Fluorine, Chlorine, Bromine, Iodine
What does the + sign mean?
it is used to separate 2 reactions or 2 products
What does the --> sign mean?
"yields," separates reactions from products
What does (s) stand for?
a designated reaction or product in the solid state; placed after the formula
What does (l) stand for?
a reaction or product in the liquid state; placed after the formula
What does (g) stand for?
a reaction or product in the gas state; placed after the formula
What does (aq) stand for?
designates an aqueous solution; placed after the formula
What is an aqueous solution mean?
the substance is dissolved in water
What is a word equation?
used to describe chemical changes, or represent a chemical equation
What is a skeleton equation?
does not indicate the relative amounts of the reactants and products
What is a chemical equation?
a shorthand expression describing a chemical reaction
What is a reactant?
the beginning substances; always written on the left of the equation
What is a product?
the ending substances; always to the right of the equation
What does a coefficient indicate?
the relative amounts of a molecule or compound involved in a chemical reaction
What does a subscript indicate?
the number of atoms of an element in a chemical formula
WHat is a catalyst?
a susbstance that speeds up the rate of a reaction buy is not consumed
What is an inhibitor?
a substance that slows doen a chemical reaction or prevents it from happening
What is an exothermic reaction?
it releases energy in the form of hear or light (feels hot)
What is an endothermic reaction?
it absorbs energy (feels cold)
What is the balanced equation and type of reaction to the following equation:
Hydrogen gas reacts with Bromine gas to produce Hydrogen bromide gas ?
H2 + Br2 --> 2HBr
synthesis
What is the the balanced equation and identify the type of chemical reaction of the following equation:
Aluminum oxide (s) decomposes when electricity is passed through it ?
2Al2O3 --> 4Al + 3O2
decomposition
What is the balanced equation to the following rxn:
P4 (s) + Br2 (l) --> PBr5 (s) ?
P4 + 10Br2 --> 4Br5
What are the 6 signs to a chemical change?
color change, heat-energy released, odor, bubbling of gas, absorption of energy, and solid precipitation
Substances that prevent the chemical reactions are called... ?
inhibitors
Which reaction does not occur?
a) 2HF + Cl2 --> F2 +2HCL
b) 2Na + ZnF2 --> 2NaF + Zn
c) Fe +CuCl2 --> FeCl2 + Cu
d) 2HCl + Mg --> MgCl2 +H2
a) 2HF + Cl2 --> F2 + 2HCl
A chemical reaction in which energy is released is...?
exothermic
According to the law of conservation of mass, if two atoms of hydrogen are used as a reactant, how many atoms of hydrogen must be a part of the product?
two
In the equation 2Al (s) + 3FE(NO3)2 (aq) --> 3Fe (s) + 2Al(NO3)3 (aq), iron has been replaced by...?
aluminum
Predict the product o fthe following reaction: MgO + CO2 -->
MgCO3
What is the formula equation for the formation of carbon dioxide from carbon and oxygen?
C + O2 --> CO2
What type of reaction is shown in the following chemcial equation? NH2 + HCl --> NH4Cl
synthesis
Which coefficients correctly balance the formula equation NH4NO2 (s) --> N2 (g) + H2O (l)?
1,1,2
When a slightly soluble solid compound is produced in a double-replacement reaction, a __________ is formed.
precipitate
The reaction Pb(NO3)2 (aq) + 2KI (aq) -->PbI2 (s) + 2KNO3 (aq) is a ...?
double-replacement reaction
What can be predicted by using an activity series?
whether a certain chemical reaction will occur
To balance a chemical equation, it may be necessary to adjust the ...?
coefficients
Magnesium hydroxide decomposes to yield magnesium oxide and ...?
water (H2O)
The reaction Mg (s) + 2HCl (aq)
--> H2 (g) + MgCl2 (aq) is a
single-replacement reaction
A chemical reaction has not occurred if the products have...?
the same chemical properties as the reactants
What happens when zinc is added to water?
no reaction occurs
A substance that speeds up a chemical reaction without undergoing a permanent change itself is...?
a catalyst
What happens when calcium metal is added to a solution of magnesium chloride?
calcium chloride forms
In what kind of reaction does one element replace a similar element in a compound?
single replacement reaction
When sodium chlorate (NaClO3) decomposes, what are the products?
sodium chloride and oxygen
What is the general structure of synthesis reactions?
A+B-->AB
What is the general structure of decomposition reactions?
AB-->A+B
What is the general structure of single-replacement reactions?
A+BY-->AY+B
What is the general structure of double-replacement reactions?
AX+BY-->AY+BX
What is synthesis?
two or more substances combined to form a more complex substance
What is decomposition?
a single substance broken down into two or more simpler substances
What is single-replacement?
a free element replaces a less active element in a compound
What is double-replacement?
the elements of reacting compounds replace each other
What do combustion reactions involve?
the reaction of a substance with oxygen that usually produces heat & light
What is another name for double-replacement reactions?
metathesis reactions
What is precipitate?
an insoluble solution
When balancing equations, which atoms must be balanced last?
hydrogen and oxygen
What must happen for a reaction to proceed?
reactants' bonds must break, and bonds must reform to make products
Reactions either ______ or ______ energy, they never stay the same.
gain; lose
What is activation energy?
the energy required to break bonds
Activation energy is always __________.
positive
What is the difference between the energy of reactants and products?
the total heat or energy of the reaction
What is the energy required to break the reactants' bonds?
activation energy
What is the point at which all bonds have been broken and products begin to reform?
activated complex
What affect do catalysts have on the activation energy of a reaction?
it lowers the activation energy
On an energy diagram, how do you know if the reaction is exothermic?
the energy level at the end of the reaction is lower than the energy level at the beginning of the reaction
On an energy diagram how do you know if the reaction in endothermic?
the energy level at the end of the reaction is higher than the energy level at the beginning of the reaction
Exothermic reactions always have _________ change in heat values.
negative
Endothermic reactions always have _________ change in heat values.
positive