Chemical Reactions Flashcards
What is chemical reaction rate ?
Chemical reaction rate is the speed at which reactants become products.
What factors effect the rate of chemical reactions and how?
TEMPERATURE :
As a general rule, heat speeds up the rate of a reaction. Heat affects molecules by making them move faster and increasing their kinetic energy .
If the temperature is low it simply takes longer for the same amount of product to be formed.
CATALYSTS : Does not increase the frequency of collisions but increases the LIKELIHOOD that each collision will be successful.
A substance which changes the speed of a chemical reaction, without itself being consumed during the reaction. They are able to lower the energy needed to start a chemical reaction by bringing particles together into the correct orientation.
PRESSURE : Concentration and Volume
The increased frequency of collisions results in a faster rate of reaction.
If the pressure of reactants are increased, there are more reactant particles for a given volume. There will be more collisions and so the reaction rate is increased. The higher the pressure of reactants, the faster the rate of a reaction will be.
Surface Area: ( Particle Size )
Increasing surface area increases the frequency of reaction, but doesn’t alter the total amount of product formed.
Several smaller particles have more surface area than one large particle and particles in the center regions can be reacted with.
Write a balanced equation for the formation of magnesium oxide
2Mg (s) + O_2 (g) → 2MgO (s)
Chemical compound of methane is
CH4
Which is more dense : air or helium
Helium is much lighter than air
Why has helium been used to replace hydrogen in the practice of aircrafts?
Helium is a noble gas meaning it is inert and much safer for use due to its low reactivity.
Rust is a compound of ? ( provide chemical formula )
Iron and Oxygen, given by the chemical formula of Fe2O3
What is Metallic bonding and what properties does it provide?
The weakest type of chemical bonding, metals bond by forming a “sea of electrons”, in which atoms in a metallic solid lose their outer electrons and form a regular lattice of positive metallic ions.
The outer electrons do not “belong” to any atom but form a pool or sea of DELOCALISED electrons that are free to move randomly throughout the fixed lattice of positive ions.
What is Ionic bonding?
Ionic bonding is the bonding between cations and anions ( metals and non-metals ) as a result of strong electrostatic attraction forces which form between the positive and negative charges.
Ionic bonding forms LATTICES.
What is Covalent bonding and what properties does it provide?
Covalent bonding forms MOLECULES and occurs when two or more non-metals form bonds with one another. In covalent bonds, all atoms involved in bond formation need to gain electrons; this can be achieved bysharing electrons.
What changes and what stays the same during chemical reactions ?
Chemical reactions involve rearranging the structure of chemical bonds between reactant molecules to form products.
In chemical reactions, matter is neither created nor destroyed, and elements are not transformed into other elements.
When do chemical reactions occur
A chemical reaction occurs when atoms rearrange their bonds to form new products.
What are chemical bonds and what is stored in them
An attraction between atoms Pairs of electrons shared between two atoms. Chemical bonds store energy
Properties of Ionic bonds
They are crystalline solids, and are brittle in nature.
They arrange in a lattice structure due to electrostatic attraction.
They have high melting and boiling points.
They are soluble in water.
Properties of Covalent bonds
The boiling/melting points of covalent compounds are low.
They are soft in nature and relatively flexible.
These compounds do not possess electrical conductivity.
Why are noble gases so unreactive?
Noble gases have eight electrons in their outermost shell, except in the case of helium, which has two.
Why are covalent bonds weaker than ionic bonds?
Ionic Bonds are formed in one big lattice whereas molecular bonds are individual clusters of atoms— hence, they are typically weaker than ionic bonds.
Name the reaction in which two or more simple substances chemically combine to form a complex substance
Synthesis reaction
Name the reaction in which a complex substance breaks down into two or more simpler substances
Decomposition reaction
