Science: Term 2 - Chemistry Flashcards
What is reaction rate?
The speed in which a chemical reaction occurs.
Give some examples of fast and slow reactions.
Fast reactions include (which possess lower activation energy);
- Neutralisation
- Magnesium Ribbon and Flame
Slow Reactions include (which produce higher activation energy);
- Corrosion
- Disintegration of radium.
List the factors that affect the rate of reaction.
- The concentration of chemicals.
- Temperature
- The presence of a catalyst.
- Pressure
- Surface area
What happens in a chemical reaction?
Bonds break, the atoms are rearranged and new bonds are formed.
BREAK, REARRANGE, FORM.
What must happen in order for a reaction to occur?
The atoms must collide, the orientation of the atoms must be compatible and the correct amount of energy must be present.
- Collide
- Orientation
- Energy
What is a catalyst?
A catalyst is a substance that increases the rate of reaction, without itself being consumed during the process.
What is an enzyme?
An enzyme is a substance that acts as a catalyst in living organisms. Chemical reactions can be regulated with the use of enzymes. It is an example of a catalyst.
What are the different types of reactions?
- Combination
- Combustion
- Displacement
- Precipitation
- Acid and a Carbonate
- Acid and a Metal
- Neutralisation
- Decomposition
What is a combination reaction?
A combination reaction is an EXOTHERMIC reaction which involves the substances simply being mixed combined together.
A+B —-> AB
Eg. magnesium + oxygen —-> magnesium oxide
What is a combustion reaction?
What are some examples of combustion reactions?
A combustion reaction is an EXOTHERMIC reaction.
A COMPLETE combustion reaction looks like this:
fuel + oxygen —–> carbon dioxide + water
An INCOMPLETE combustion reaction looks like this:
hydrocarbon + oxygen —–> carbon monoxide + carbon + water
Some examples include:
- Combustion of propane
- Burning of wood or coal
- Combustion of natural gas
What is a displacement reaction?
A displacement reaction is generally EXOTHERMIC. It involves one metal and another compound of a different metal.
Eg. copper + silver nitrate —–> copper nitrate + silver
All are metals.
What is a precipitation reaction?
A precipitation reaction is generally an EXOTHERMIC reaction. To identify this reaction, (aq) is written beside the substances, as state symbols to show they aqueous substances. The elements are also swapped around. It is the opposite of dissolving. It typically becomes cloudy and a precipitate is formed.
Eg. sodium hydroxide(aq) + magnesium chloride(aq) —–> sodium chloride(aq) + magnesium hydroxide(aq)
What is an acid and a carbonate reaction?
An acid and a carbonate reaction is an EXOTHERMIC reaction.
Acid + carbonate —–> salt + water + carbon dioxide
Eg. hydrochloric acid + copper carbonate —-> copper chloride + water + carbon dioxide
How can you test for different gasses in an acid and carbonate reaction?
Hydrogen - a squeaky pop
Oxygen - re-light a glowing splint
Carbon Dioxide - extinguish the flame
What is an acid and a metal reaction?
It is an EXOTHERMIC reaction.
Metal + acid ——> salt + hydrogen
Eg. sulfuric acid + zinc —–> zinc sulphate + hydrogen
What is a neutralisation reaction?
It is generally an EXOTHERMIC reaction.
Acid + base —–> salt + water
Eg. sulfuric acid + potassium hydroxide —–> potassium sulphate + water
(Bases can be identified with OH, hydroxide.)
What is a decomposition reaction?
It is an ENDOTHERMIC reaction. It involves the split of substances into their own respective substances.
AB —-> A + B
Eg. calcium carbonate —-> calcium oxide + carbon dioxide
What is corrosion?
Corrosion is the breakdown of materials due to chemical reactions. It is usually present in metals during oxidation, when with air molecules the presence of water combine. (It is an oxidation reaction.)
What is the word equation for the rusting of iron?
iron + oxygen + water —-> iron oxide (rust)
What are some ways of preventing iron from rusting?
- Galvanising (coat the iron in zinc)
- Oiling
- Greasing
- Painting
- Coating with plastic
What is an exothermic reaction?
An exothermic reaction is a reaction in which energy is RELEASED into the surrounding environment. This is because the reactants have more energy than the products.
The reaction is warm.
The overall enthalpy is negative (as it releases more energy than it absorbs).
What is an endothermic reaction?
An endothermic reaction is a reaction in which energy is TAKEN IN from the surroundings. This is because the products have more energy in the reactants.
The reaction is cold.
The overall enthalpy is positive (as it absorbs more energy as it releases).
What is a monomer?
A monomer is a molecule that can be bonded to other identical monomers to create a polymer.
What is polymer?
A polymer is a substance which has a molecular structure that is built up of smaller units of molecules bound together (monomers).
What is the order of the scientific method?
- Aim
- Hypothesis
(Variables) - Equipment
- Method
(Risk Assessment) - Results
- Discussion
- Conclusion
