8F Reactions Flashcards
State two observations that a chemical reaction is occurring.
Temperature change, colour change, fizzing, smell, irreversible change
Describe what an exothermic reaction is.
A reaction which released thermal energy
Give one example of an exothermic reaction.
Combustion/burning, metal and acid, neutralisation/acid and alkali
What is a neutralisation reaction?
An acid reacts with an alkali
What happens in terms of energy when bonds are broken?
Energy is taken in
What happens in terms of energy when bonds are made?
Energy is given out
True or false: During an exothermic reaction, products have more energy than reactants.
How can we measure whether there is a temperature change during a reaction?
Thermometer
What happens when bonds in reactants are broken?
Energy is absorbed
What happens when bonds in products are made?
Energy is released
What are the reactants in an instant cold pack?
Water and ammonium nitrate
How does the instant cold pack work?
water and ammonium nitrate react in an endothermic reaction
Identify the independent variable during this investigation.
Mass of ammonium nitrate
Identify the dependent variable during this investigation.
Temperature change
Identify the control variables during this investigation.
Volume of water, the balance reading zero before use
How do you calculate the temperature change?
By finding the difference between the before and after temperature
What is a catalyst?
A substance that can be added to a chemical reaction to speed it up
Why are catalysts described as “specific”?
A catalyst which works for one reaction, will not work for another reaction
How do catalysts speed up reactions?
By lowering the activation energy
What is an enzyme?
A biological catalyst
Give an example of a reaction which is sped up by an enzyme
Digestion, respiration, photosynthesis
What is the name of the part of the enzyme which has a specific shape?
Active site
Which catalyst is used to manufacture ammonia?
Iron or platinum
Give one reason why industrial processes use catalysts
More product made in a shorter time, enzymes can be re-used, lower energy costs during production
What are the two reactants of combustion?
Fuel and oxygen
In addition to the reactants, what else is needed for combustion?
Heat
What are the products of combustion?
Carbon dioxide and water
What is a fuel?
A material that burns to release energy