Characteristics of Chemical Reactions
Why do chemical reactions sometimes bubble?
Gas is being released.
Does the mass change in a chemical reaction?
No, the mass stays the same before and after a chemical reaction.
Flammability is a....
Chemical property
Two chemicals were combined in a flask and the flask turned cold. This indicates what type of chemical reaction?
endothermic or exothermic?
What is it called when a solid is formed during a chemical reaction?
precipitate
What is the number called BEFORE an atomic symbol in a chemical equation and what does it mean?
coefficient
the number of that molecule
Oil and water separating into layers is an example of –
(type of property and what is it called?)
The physical property of density.
A campfire is an example of a(n) –
endothermic reaction
exothermic reaction
exothermic
Fill in the blanks for the correct vocabulary in a chemical reaction:
______ + _________ = _________
reactant + reactant = product
What is the small number after an atomic symbol called and what does it mean?
subscript
It tells the number of that atom present
How do you calculate density?
Density is equal to MASS / VOLUME
What is the difference between an endothermic and exothermic chemical reaction?
endothermic reactions absorb heat and exothermic reactions release heat.
Two clear chemicals combine. The solution turns yellow and gets cold. What evidence suggests that a chemical change took place?
The solution turned yellow and got cold
What is the difference between an open and closed system?
An open system can exchange energy and matter with it's surroundings.
Solubility is a...
physical property
What happens to the temperature in an endothermic chemical reaction?
What happens to the temperature in an exothermic chemical reaction?
endothermic: temperature goes down
exothermic: temperature goes up
Why is a saltwater solution only a physical change?
The salt atoms and water atoms do not recombine to make a new substance.
Is this equation balanced or unbalanced?
N2 + 6H2 -> 2NH6
Yes, there are 2 Nitrogen atoms on each side and 12 hydrogen atoms on each side
Find the density of an item that has a mass of 100 grams and a volume of 25 cm3
4 g/cm3
During a chemical reaction, from where is the energy stored or released?
The bonds between atoms