Reactions 2 Flashcards
How do u know a chemical reaction has happened
Change in temp, chnage in colour, change in mass, bubbles
What is the balanced symbol equation for magnesium and oxygen reacting
2MG+O(small)2 ——> 2MgO
Define catalyst
A chemical that speeds up a reaction by lowering the activation energy but it is not used up
Define reactants
The chemicals that react together in a chemical reaction to form the products
Define products
What is produced or formed in a chemical reaction
Define combustion
A reaction where oxygen is reacted with a substance (hydrocarbon) to burn it. It forms water and carbon dioxide
Define exothermic
A reaction that gives out energy into the surroundings. Increase in temp
Define endothermic
A reaction where energy is taken in from the surroundings. Decrease in temp
Word equation of magnesium and oxygen reacting
Magnesium+oxygen——> magnesium oxide
Particle diagram showing magnesium and oxygen reacting
: + •-• ——> :=:
What is the equation for combustion
Hydrocarbon+ oxygen —-> carbon dioxide+water
Equation for incomplete combustion
Hydrocarbon+little to no oxygen ——-> carbon monoxide + water
What is thermal decomposition
When a chemical substance (compound) breaks down (decomposes) into 2 or more chemical substances.
Example of thermal decomposition
Calcium carbonate——-> calcium oxide + carbon dioxide
What does conservation of mass mean
No atoms or destroyed or created. They are rearranged to form the products so the mass of the reactants and products is equal.
Jessica used 0.24g of mag and put it in a Bb. at the end the product weighed 0.80g. What reacted with the mag and what was the mass of this?
Oxygen
0.56g
What is bond energy
Energy to break bonds- energy to make bonds
How to remember bond energy
Bendomexo
Give an example of endothermic reaction
Ice pack have a drop in temp so they appear cold to soothe injuries. Energy is absorbed by the ice pack from the surroundings to make it appear cold. This makes is an endothermic reaction
Give an example of an exothermic reaction
Combustion. Fuels such as methane react with oxygen completely to create water and carbon dioxide. this is called combustion and is an exothermic reaction bc energy is released into the surroundings causing a temp increase
In an exothermic graph which is higher
Reactants are higher than products bc they have more energy
In an endothermic Graph which is higher
Reactants are lower than products bc energy is taken i during the reaction
Describe a reaction graph
Y axis is energy x axis is progress of reaction (time)
Examples of thermal decomposition reactions
Heat
Copper carbonate ——> copper oxide + carbon dioxide
Sodium calcium lithium potassium
Why does the mass apparat to decrease in a thermal decomposition reaction
When heated the compound break down, atoms change and carbon dioxide (g) is released. Gas moves freely in open systems (the air)
In a Bond Energy equation, what does it mean if the answer is a negavtive
It means it is an exothermic reaction. if the number was positive it would be endothermic
