Chemical Equations Flashcards
What is the basic “formula” for a chemical reaction?
Reactants—>products
Chemical reaction can be abbreviated as…
rxn
Chemical…are made up of…representing the…and…
Chemical equations are made up of symbols representing the reactants and products.
How do you remember which elements are always diatomic molecules?
HOFBrINCl: Hydrogen, oxygen, fluorine, bromine, iodine, nitrogen, chlorine
What is a catalyst?
A substance that speeds up a reaction but is not used up in the reaction.
What does this symbol do in a chem equation: +
Separates two or more reactants/products.
What does this symbol do in a chem equation: —>
Means “yields/produces,” used to separate reactants from products
What does this symbol do in a chem equation: (s)
Indicates a reactant/product in solid state- placed after formula
What does this symbol do in a chem equation: (l)
Indicates a reactant/product in liquid state- placed after formula
What does this symbol do in a chem equation: (g)
Indicates a reactant/product in gaseous state- placed after formula
What does this symbol do in a chem equation: (aq)
Indicates an aqueous solution, substance is dissolved in water; placed after formula
What does this symbol do in a chem equation:—-> with “heat” or a triangle on top:
Indicates that heat is applied to the reaction
What does this symbol do in a chem equation:—–> with an element symbol (like Pt) on top:
Indicates that the element was used as a catalyst
How do you balance an equation?
Place coefficients in front of substances.
Can you balance an equation by changing subscripts?
No, because that changes the reactants/products themselves.
Why must equations be balanced?
In order to obey the law of conservation of mass.
Read the following reaction: Two molecules of water (H2O) produces 1 molecule of oxygen (O2) and 2 molecules of hydrogen (H2). How do you say this using moles?
Two moles water produces 1 mole oxygen and 2 moles hydrogen.
Define chemical reaction.
The process by which some substances change into different substances.
What happens with atoms and their bonds in a chem reaction?
The types and ratios of atoms stay the same, but the bonds of the reactants break and form new bonds to make the products, therefore rearranging the atoms.
What do reactants do?
They start the reactions.
What are the products in a reaction?
The end result.
What is the basic equation for a synthesis reaction?
A+B—>C
What is the basic equation for a decomposition reaction?
AB—>A+B
What is the basic equation for a double replacement reaction?
AB+CD—>AD+CB
What is the basic equation for a single replacement reaction?
A+BC—>B+AC
What is the basic equation for a combustion reaction?
Fuel+oxygen—>carbon dioxide+water
All chemical reactions involve…
energy.
Why is energy involved in chemical reactions?
It takes energy to break the bonds of the reactants and energy is released when new bonds are formed for th e products.
What is an exothermic reaction?
Energy released in the reaction is greater than energy used. The energy is released as light or heat. (Energy released by formation of bonds in products exceeds energy used to break reactants’ bonds.)
What is an endothermic reaction?
Energy used up in the reaction (to break reactants’ bonds) is greater than energy released in the reaction (as products form bonds). Energy is absorbed, not released.
What is the energy in an exothermic reaction released as?
Light or heat.
When you write a chemical equation from words, and you are dealing with a one-word reactant/product, how do you write its symbol?
One word= element. If it is a HOFBrINCl element, it is diatomic, write as such (N2). If it is not, just write the element symbol (Zn). DO not worry about charges.
When writing a chemical equation from words, how do you write a two-word reactant/product?
Two words means it is a compound. If it is ionic, use ion charges. If it is covalent, it is either an acid or a binary covalent. Write the binary covalent with the subscripts that correspond to prefixes, and use reference sheet to write acid formulas (these start with hydrogen).
What are two standard “templates” for composition/synthesis reactions?
Element+element—>binary compound
Compound+compound—> new compound
Composition/synthesis reactions have how many products?
1
What are two standard “templates” for decomposition reactions?
Binary compound—> element + element
Compound—>element + compound
How many reactants and products are in decomposition reactions?
1 reactant, and more than one product
What is the standard “template” for single replacement reactions?
Element + compound—> new element + new compound
What is the standard “template” for double replacement reactions?
Compound+compound—> new compound+ new compound
What elements does a hydrocarbon contain?
Hydrogen, carbon, and sometimes oxygen
What is the standard template for combustion (of a hydrocarbon)?
Hydrocarbon + oxygen—> carbon dioxide + water
