MT2 Flashcards
How can chemical reactions be identified?
Energy changes
What are the two energy changes?
Exothermic reaction & Endothermic reaction
What is an exothermic reaction?
An exothermic reaction RELEASES energy to their surroundings, the temperature will INCREASE and the PRODUCTS will have LESS chemical energy than the REACTANTS.
What is an endothermic reaction?
An endothermic reaction ABSORBS energy, causing the temperature to DROP. The products (of the reaction) will have MORE chemical energy than the reactants.
What are reactants in a word equation?
The substances that react together
What are the products in a word equation?
The substances formed
What are the state symbols in a word equation?
Solid = (s)
Liquid = (l)
Gas = (g)
Aqueous solution = (aq) (means dissolved in pani)
What is a fuel?
A substance that BURNS in OXYGEN to release ENERGY
What is the composition of air?
Nitrogen (79%) Oxygen (19%) Carbon Dioxide (0.04%) Argon (1.96%)
What is combustion?
Combustion is another name for a chemical reaction of a fuel burning (in oxygen)
What does it mean when a substance burns?
Reacts with oxygen
What is the test for oxygen?
Oxygen relights a glowing splint.
When carbon burns in oxygen, what does it produce?
Carbon dioxide (CO₂). Or Carbon monoxide, if INCOMPLETE COMBUSTION takes place.
What is the test for carbon dioxide?
Carbon dioxide turns lime water cloudy.
What is incomplete combustion?
When a lack of oxygen is produced.
What is produced as a result of incomplete combustion?
Carbon monoxide.
What is the word equation for carbon dioxide?
carbon + oxygen → carbon dioxide
What is the test for hydrogen?
Hydrogen burns with a squeaky pop.
What is the word equation for water?
hydrogen + oxygen → hydrogen oxide (water)
What are the three fossil fuels?
Crude oil, natural gas and coal
When were fossil fuels formed?
Millions of years ago.
How are crude oil and natural gas made?
They were made MILLIONS OF YEARS AGO when DEAD CREATURES UNDER THE SEA BED are exposed to HEAT and PRESSURE. Natural gas can also be found next to it.
How is coal made?
Coal is made when trees/plants millions of years ago were exposed to HEAT and PRESSURE, causing them to change chemically.
What are hydrocarbons?
Hydrocarbons are compounds that only contain hydrogen and carbon.
What is the word equation for burning a hydrocarbon?
hydrocarbon + oxygen → water + carbon dioxide
How can we prove that water + carbon dioxide is produced from burning a hydrocarbon?
Lime water turned cloudy which indicates carbon dioxide is present
Water vapour condensed at 100°C
What does it mean when fossil fuels are FINITE?
It means that they run out. Another way to say this is that they are NON-RENEWABLE.
What is hydrogen being hailed as?
A fuel of the future because it is inexpensive and can be extracted from water. It is also the most abundant element in the universe
A REACTION IS ENDOTHERMIC IF… (CHOOSE ONE)
A - energy is required to start the reaction
B - heat is released during the reaction
C - the temperature drops during the reaction
D - the temperature rises during the reaction
C - the temperature drops during the reaction
A REACTION IS EXOTHERMIC IF… (CHOOSE ONE)
A - energy is absorbed from the surroundings
B - energy is released to the surroundings
C - energy is required to start the reaction
D - there is no energy change
B - energy is released to the surroundings
What do crude oil and natural gas mainly consist of?
Hydrocarbons.
What are the 3 things required for burning?
Oxygen, heat energy, fuel
What are fossil fuels?
Fossil fuels are fuels that contain hydrocarbons, are finite and are made from plants, trees and animal remains millions of years ago.
