chem Flashcards
Exothermic Reaction
Gives out energy to the surroundings usually in the form of heat
Endothermic Reaction
Takes energy from its surroundings in the form of heat, showing a fall in temp
reaction profiles?
are diagrams that show the relative energies of the reactants and products in a reaction, it also shows how energy changes over time
Activation energy, also known as…
Ea
Activation energy?
minimum amount of energy the reactants need to collide with each other and react.
Exothermic reactions in reaction profiles?
products are at a lower energy than the reactants
Endothermic reactions in reaction profiles?
products are at a higher energy than the reactants because the energy is taken in.
Enthalpy change in Exothermic Reactions?
Negative
Enthalpy change in Endothermic?
Postitive
Enthalpy Change?
amount of heat evolved or absorbed in a reaction carried out at constant pressure.
Rate of reaction dependencies?
1) temp
2) concentration of a solution or pressure of gas
3) Surface area, changes are dependant of the size of the solid
4) Presence of a catalyst
what does more collisions do to the rate of reactions?
It gets it higher
name 4 things that increase the rate of reactions?
1) higher temp
2) higher concentration/pressure
3) Catalysts
4) Smaller solid particles combining more Surface Area
reactions only happen if…
particles collide with enough energy
In gas, what does it mean by increasing the pressure?
getting the particles to be more crowded, frequency of collisions will increase.
What happens if a solution is made more concentrated
It means there are more particles of reactant in the same volume
What will increase when a solid is breaking into smaller pieces?
Surface area
A catalyst is a substance which increases the rate of a reaction without…
being chemically changed or used up in the reaction.
will a catalyst change the products of a reaction?
No, so the reaction equation will stay the same.
Because it isn’t used up, you can use catalysts for large amounts of reactants.
Do Catalysts work with all reactions?
No.
How do catalysts work?
They decrease the activation energy for a reaction to occur, making it quicker. They do this by providing an alternative reaction pathway that has a lower activation energy
What does a catalyst do to the particles?
more of the particles will have the minimum amount of energy needed for a reaction to occur when particles collide.
What substances make great fuels?
Hydrocarbons.
Is burning a combustion reaction?
Yes.
What energy does fuel release when burning?
Heat.
Why do Hydrocarbons make great fuels
When you burn them in oxygen, they give out lots of heat energy. This is a very exothermic reaction.
Combustion Equation?
hydrocarbon + oxygen –> carbon dioxide + water
What is the process called when there isn’t enough oxygen around for a complete combustion reaction.
Incomplete combustion.
The products of incomplete combustion contain ___________ than carbon dioxide.
less oxygen.
What does an incomplete combustion produce?
carbon monoxide and Soot.
What is produced when crude oil is burnt?
Sulfur dioxide, nitrogen oxides. (these MAY be produced).
How are nitrogen oxides created?
When the temp is high enough for the nitrogen and oxygen in the air to react.
Nitrogen oxides include… and …
nitrogen monoxide (NO) and nitrogen dioxide (NO2).
What forms when sulfur dioxide and nitrogen oxides mix with water vapor in the clouds?
dilute sulfuric acid and nitric acid.
What will you get if you heat a metal carbonate?
carbon dioxide and metal oxide.
Thermal decomposition?
a substance breaks down into simpler substances when heated.
Copper Carbonate(II) thermal decomposition and equation?
Copper(II) carbonate is a green powder that will easily decompose to form carbon dioxide and copper(II) oxide when you heat it.
Equation: CuCO3 (s) –> CuO (s) + CO2(g)
To do the experiment, heat copper(II) carbonate then collect the gas that’s given off in a test tube.
The gas that is collected can then be tested to see if it is CO2 using limewater.
First 5 Hydrocarbons
1) Methane
2) Ethane
3) Propane
4) Butane
5) Pentane
First 5 Hydrocarbons
1) Methane
2) Ethane
3) Propane
4) Butane
5) Pentane
