Endo / Exo
The kind of reaction where energy is released.
What is Exothermic
Is this balanced?
H₂ + O₂ → H₂O
(Show me the atom accounting to prove it)
NO
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RECTANTS l PRODUCTS
H 2 l H 2
O 2 l H 1
A bike chain turns brown and crusty. Your friend says - your bike chain is rusty.
Is this a chemical reaction why or why not?
Yes - rust is a chemical reaction because there was an unexpected color change and a new substance was formed
If heat is added to a solid, what phase change will eventually occur?
Melting
What is an open system in terms of chemical reactions?
A system where matter can enter or leave.
This happens to the temperature of the surroundings during an endothermic reaction.
What is a temperature DECREASE?
Is this equation balanced?
N₂ + 3H₂ → 2NH₃
Prove it by providing the atom accounting!
YES!
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REACTANTS l PRODUCTS
N 2 l N 2
H 6 l N 6
You are painting your room and you mix two paints together to get a new color.
Is this a chemical change why or why not?
This is not a chemical change, it is a physical change. The colors are blending, there is no new substance forming. It is just a mixture.
What happens to the molecules when a substances begins to freeze?
The molecules slow down and come together
What is the difference between a chemical change and a physical change?
A chemical change creates new substances, while a physical change does not.
Oxidation is an example of this kind of chemical reaction.
What is exothermic?
Is this equation balanced?
CH₄ + O₂ → CO₂ + H₂O
Prove it with the atom accounting!
NO!
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Reactants l Products
C 1 l C 1
H 4 l H 2
O 2 l O 3
In a reaction, the container feels cold to the touch, and no visible gas or color change occurs.
This is a chemical change. The temperature drop indicates that an endothermic reaction has occurred, absorbing heat from the surroundings.
What happens to the molecules during evaporation?
The molecules speed up and spread apart.
What does the Law of Conservation of Matter state?
Matter cannot be created or destroyed in a chemical reaction.
This reaction feels cold. Where should heat go in the equation?
N2 + O2 🡪 2NO
In the PRODUCTS!
Look at the equation: P₄ + O₂ → P₄O₁₀. What must the coefficient for O₂ be to balance it?
5O2
You cook an egg in the frying pan for breakfast.
Is this an example of a chemical change why or why not?
YES!
There are colors changing and a new substance is formed. It is also irreversible, as the egg an not be "uncooked".
What is the term for the phase change from gas to liquid?
Condensation
How do we know if a chemical formula is balanced?
It must have the same amount of each type of element in both the reactants and products.
Below is the chemical formula for photosynthesis...
Endothermic
Which of the following steps is necessary to balance this equation? Fe + O₂ → Fe₂O₃ (Choose the correct coefficient for Fe)
In a reaction, the container feels cold to the touch, and no visible gas or color change occurs. How do you know a chemical reaction has taken place, and what kind of reaction might it be?
The temperature drop indicates that an endothermic reaction has occurred, absorbing heat from the surroundings.
Explain the difference between evaporation and boiling.
Evaporation occurs at the surface of a liquid at any temperature, while boiling happens throughout the liquid at its boiling point.
What is a precipitate?
A solid that forms from a solution during a chemical reaction.