Uses symbols to represent a chemical reaction and shows the relationship between the products and the reactants.
100
What is the first step when balancing chemical equations?
List and count the number of atoms on each side?
100
What type of reaction MUST have oxygen (by itself!) as a reactant?
combustion
200
What is a reactant?
substance that participates in a chemical reaction--left hand side of equation
200
How can you tell when an exothermic reaction has taken place?
Heat is released; increased temperature, you can feel heat
200
What does the arrow sign mean in a chemical equation?
Yields; produces; forms; creates
200
How many oxygen do you have on the reactant side in the following equation?
3C2H6O + 3O2 (yields) 2CO2 + 2H20
9
200
What happens in a double replacement reaction?
2 COMPOUNDS exchange ions
300
What is the product?
The substance that is formed in a chemical reaction--right hand side of the equation.
300
Do reactants or products have more energy in an EXOTHERMIC reaction?
reactants
300
Why do chemical equations have to be balanced?
Law of Conservation of Mass
300
How do you change the number of atoms in a compound? For example, how do you increase the number of chlorine atoms in the compound MgCl2?
Put a number in front--the coefficient--gets applied to each element in the compound.
300
What does it mean if a substance is reduced?
It accepts (gains) electrons
400
What are 2 signs that a chemical reaction has taken place?
bubbles forming, color change, odor change
400
What is activation energy?
The amount of energy required to start a reaction.
400
When you write a chemical equation, what is written first, before the arrow?
reactants
400
In the equation for creating water, you have hydrogen gas combining with oxygen gas to form water:
2H2 + O2 (yields) 2H2O
Why do hydrogen and oxygen gas have a 2 after them?
They are diatomic elements--part of BrINClHOF--if found ALONE, they will have two atoms
400
Zn + 2HCl (yields) ZnCl2 + H2
What type of reaction is this?
single-displacement or single-replacement
500
Explain what happens when a chemical reaction occurs
Bonds break apart and rearrange
500
What requires more activation energy; an endothermic or an exothermic reaction? Why?
Endothermic reaction; reactants have lower potential energy to start, so they need to take in energy from their surroundings.
500
Write the following as a balanced chemical equation:
Sodium chloride reacts with water to form chlorine gas, hydrogen gas, and sodium hydroxide.
2NaCl + 2H20 (arrow) Cl2 + H2 + 2NaOH
500
Balance the following equation:
Pb(NO3)2 + KI (yields) KNO3 + PbI2
Pb(NO3)2 +2KI (yields) 2KNO3 + PbI2
500
S8 + 8O2 (yields) 8SO2 + energy
What type of reaction is this?