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Chemical Changes
Chemical Equations & Reactions
Energy & Chemical Reactions
Addition, Decomposition, & Combustion Reactions
Chemical Reactions Miscellaneous
100
Bubbling may be evidence of a chemical reaction, indicating formation of a new gas. Name three other observations that may be evidence of chemical change and what each indicates.
Turning cloudy may indicate a new solid is forming. A change in temperature may indicate chemical bonds are changing. A color change may indicate a new substance is forming.
100
What in a chemical equation shows the direction of the reaction?
The arrow indicates the direction, from reactants to products.
100
What is it called when elements react with Oxygen and give off energy?
Combustion!
100

What kind of reaction is this, 

2H2O(l) -----> 2H2(g)+ O2(g)  

It is a decomposition reaction.

100

What notation identifies the state of each substance in a chemical reaction?

(g) gas, (s) solid, (l) liquid, (aq) aqueous

200
These are broken and reformed in a chemical reaction.
What are chemical bonds.
200
Why are you not allowed to change a subscript when balancing a chemical equation?
The subscript indicates the number of atoms per molecule. A change in the subscript would make the formula represents an entirely different compound.
200
What is an example of an endothermic reaction that sustains life on Earth?
Photosynthesis.
200
Hydrocarbons are composed of what atoms?
Hydrogen and carbon.
200

What is an example of a chemical reaction that gives off energy in the form of heat and light?

Burning/combustion

300
Ice melting is an example of what kind of change? Explain.
Ice melting is an example of a physical change. The substance (water) changes state, from solid to liquid, but it remains the same substance.
300
What does it mean to say that mass is conserved in a chemical reaction?
Matter changes when chemical reactions happen, but matter is never lost. No new atoms are created!
300
What role does activation energy play at the start of a chemical reaction?
Activation energy breaks bonds, making atoms available to form new bonds.
300

Name 3 non metal atoms

e.g. O, C, N, etc.

300

What does 'aq' mean?

Agueous and means that is is soluble in water at room temperature.

400
What is the name for substances that combine and change in a chemical reaction?
Reactants!
400
Which of the following reactions is balanced? 4KMnO4 ---------> 2K2O + 4MnO + 4O2 2N2O5 + NO -----> 4NO2 Cl2 + 2Br --------> 2Cl + Br2
Cl2 + 2Br --------> 2Cl + Br2
400
What does a spark, a flame, or heat provide to some chemical reactions?
Activation energy.
400

Name 4 metals

e.g. Cu, K, Na, Mg, Fe etc.

400

 Is NaNO3 soluble or insoluble?

 soluble

500
Is dissolving sugar in water a chemical change or a physical change?
A physical change.
500
If you compare the mass of baking soda and vinegar before and after being mixed in an open beaker, would you expect it to be the same, or different? Why?
You would expect the mass to decrease because of escaped gas.
500
If the energy released by the formation of products is greater than the activation energy, what kind of reaction is it?
An exothermic reaction
500

What is the difference between incomplete and complete combustion?

A complete combustion reaction forms CO2 as a product.

Incomplete combustion reactions form CO or C as a product.

500

Which is the more reactive metal out of K and Mg?

K