Chemical Equations
A chemical equation is just a representation of a chemical reaction.
Reactants -------> Products
Chemical can be written as word equations, or formula equations. Formula equations can be balanced or unbalanced.
Word Equation- Potassium Bromide plus Iron --> Iron Bromide plus Potassium
Formula Equation- KBr + Fe --> FeBr2 + K
Each element has a charge, and you have to take that into consideration when writing equations.
All the elements in Group 1 have a +1 charge
Group 2, +2 charge
Group 3-12, +2
(Group 11 has a +1 charge)
Group 13, +3
Group 14, +4
Group 15, -3
Group 16, -2
Group 17, -1
And Group 18 does not have a charge because they are already happy with their 8 Valence Electrons.
A chemical equation is just a representation of a chemical reaction.
Reactants -------> Products
Chemical can be written as word equations, or formula equations. Formula equations can be balanced or unbalanced.
Word Equation- Potassium Bromide plus Iron --> Iron Bromide plus Potassium
Formula Equation- KBr + Fe --> FeBr2 + K
Each element has a charge, and you have to take that into consideration when writing equations.
All the elements in Group 1 have a +1 charge
Group 2, +2 charge
Group 3-12, +2
(Group 11 has a +1 charge)
Group 13, +3
Group 14, +4
Group 15, -3
Group 16, -2
Group 17, -1
And Group 18 does not have a charge because they are already happy with their 8 Valence Electrons.
This video goes more in depth on how to write a chemical equation, and it also talks about a few things we're going to cover in this section.
Balancing Equations
Let's say you are given the equation Mg3N2 + H2O ---> MgO + NH3
This equation is unbalanced because the reactants (all the stuff on the left) are not equal to the products (all the stuff on the right). To balance this equation you first have to write the unbalanced, and then put a little chart underneath to help you record how many of each element you have on each side.
Mg3N2 + H2O ---> MgO + NH3
Mg- 3 |Mg- 1
N- 2 |N- 1
H- 2 |H- 3
O- 1 |O- 1
This shows how many you currently have on each side. Now you're trying to make them even, so look at O, there is 1 O on each side so that means O is balanced. Now look at Mg, There are 3 Mg's on the reactant side, but only 1 on the product side, so lets put a 3 in front of the Mg on the product side. The 3 is our coefficient.
Mg3N2 + H2O ---> 3MgO + NH3
Mg- 3 |Mg- 3
N- 2 |N- 1
H- 2 |H- 3
O- 1 |O- 3
But now since we put a 3 in front of the product Mg, it affected O too. So we have to make three reactant O's now by putting a 3 in front of H2O. Doing so will make the reactant Hydrogen change to 6, because there is already 2 H's, and 3x2= 6.
Mg3N2 + 3H2O ---> 3MgO + NH3
Mg- 3 |Mg- 3
N- 2 |N- 1
H- 6 |H- 3
O- 3 |O- 3
Let's say you are given the equation Mg3N2 + H2O ---> MgO + NH3
This equation is unbalanced because the reactants (all the stuff on the left) are not equal to the products (all the stuff on the right). To balance this equation you first have to write the unbalanced, and then put a little chart underneath to help you record how many of each element you have on each side.
Mg3N2 + H2O ---> MgO + NH3
Mg- 3 |Mg- 1
N- 2 |N- 1
H- 2 |H- 3
O- 1 |O- 1
This shows how many you currently have on each side. Now you're trying to make them even, so look at O, there is 1 O on each side so that means O is balanced. Now look at Mg, There are 3 Mg's on the reactant side, but only 1 on the product side, so lets put a 3 in front of the Mg on the product side. The 3 is our coefficient.
Mg3N2 + H2O ---> 3MgO + NH3
Mg- 3 |Mg- 3
N- 2 |N- 1
H- 2 |H- 3
O- 1 |O- 3
But now since we put a 3 in front of the product Mg, it affected O too. So we have to make three reactant O's now by putting a 3 in front of H2O. Doing so will make the reactant Hydrogen change to 6, because there is already 2 H's, and 3x2= 6.
Mg3N2 + 3H2O ---> 3MgO + NH3
Mg- 3 |Mg- 3
N- 2 |N- 1
H- 6 |H- 3
O- 3 |O- 3
Now everything is balanced except for N and H. You'll see that you need 2 N's on the product side, and 6 H's. You already have 3 so the same rule applies, just put a 2 in front of N on the product side and it will finish balancing the equation because 2x3= 6, so both N and H will be balanced.
Mg3N2 + 3H2O ---> 3MgO + 2NH3
Mg- 3 |Mg- 3
N- 2 |N- 2
H- 6 |H- 6
O- 3 |O- 3
And that's how you balance an equation! Pretty simple right? Just basic multiplication.
Mg3N2 + 3H2O ---> 3MgO + 2NH3
Mg- 3 |Mg- 3
N- 2 |N- 2
H- 6 |H- 6
O- 3 |O- 3
And that's how you balance an equation! Pretty simple right? Just basic multiplication.
5 Types of Reactions
1. Synthesis- two or more elements form a compound
Element + Element ---> Compound
A + B= AB
Ex. Sodium + Chlorine ---> Sodium Chloride
Na + Cl2 ---> NaCl
Na- 1 |Na- 1
Cl- 2 |Cl- 1
2Na + Cl2 ---> 2NaCl
Na- 2 |Na- 2
Cl- 2 |Cl- 2
2Na + Cl2 ---> 2NaCl
2. Decomposition- A compound that breaks down into elements and/ or smaller compounds
Compound ---> Element + Element
AB ---> A+ B
Ex. Potassium Nitride ---> Potassium + Nitrogen
K3N ---> K + N2
K- 3 |K- 1
N- 1 |N- 2
2K3N ---> 6K + N2
K- 6 |K- 6
N- 2 |N- 2
2K3N ---> 6K + N2
1. Synthesis- two or more elements form a compound
Element + Element ---> Compound
A + B= AB
Ex. Sodium + Chlorine ---> Sodium Chloride
Na + Cl2 ---> NaCl
Na- 1 |Na- 1
Cl- 2 |Cl- 1
2Na + Cl2 ---> 2NaCl
Na- 2 |Na- 2
Cl- 2 |Cl- 2
2Na + Cl2 ---> 2NaCl
2. Decomposition- A compound that breaks down into elements and/ or smaller compounds
Compound ---> Element + Element
AB ---> A+ B
Ex. Potassium Nitride ---> Potassium + Nitrogen
K3N ---> K + N2
K- 3 |K- 1
N- 1 |N- 2
2K3N ---> 6K + N2
K- 6 |K- 6
N- 2 |N- 2
2K3N ---> 6K + N2
3. Single Replacement- An element and compound react to form a different element and compound
Element + Compound ---> Element + Compound
A + BC ---> AC + B
These reactions do not always occur. When they do, "like will replace like," meaning for instance metals will only replace metals. You need to use the Activity Series chart of metals in order to see if the reaction can happen.
Element + Compound ---> Element + Compound
A + BC ---> AC + B
These reactions do not always occur. When they do, "like will replace like," meaning for instance metals will only replace metals. You need to use the Activity Series chart of metals in order to see if the reaction can happen.
Ex. Lithium + Zinc Acetate ---> Zinc + Lithium Acetate
This reaction can happen because if you look on the chart you see that Lithium is higher up than Zinc.
Li + Zn(C2H3O2)2 ---> Zn + Li(C2H3O2)
Li- 1 |Li- 1
Zn- 1 | Zn- 1
C2H3O2- 2 |C2H3O2- 1
2Li + Zn(C2H3O2)2 ---> Zn + 2Li(C2H3O2)
Li- 2 |Li- 2
Zn- 1 | Zn- 1
C2H3O2- 2 |C2H3O2- 2
2Li + Zn(C2H3O2)2 ---> Zn + 2Li(C2H3O2)
Copper + Aluminum Sulfate ---> No Reaction
This reaction cant happen because if you look at the chart you'll see that Copper is below Aluminum. Reactions only work if the one you're swapping in is higher on the chart than the one you're swapping out.
4. Double Replacement- Two compounds react to form two new compound
Compound + Compound ---> Compound + Compound
AB + CD ---> AD + BC
You do not use the activity series sheet for these reactions.
Ex. Cu2(SO4) + Be(C2O4) --->Cu2(C2O4) + Be(SO4)
Cu- 2 |Cu- 2
SO4- 1 |SO4- 1
Be- 1 |Be- 1
C2O4- 1 |C2O4- 1
Already Balanced
This reaction can happen because if you look on the chart you see that Lithium is higher up than Zinc.
Li + Zn(C2H3O2)2 ---> Zn + Li(C2H3O2)
Li- 1 |Li- 1
Zn- 1 | Zn- 1
C2H3O2- 2 |C2H3O2- 1
2Li + Zn(C2H3O2)2 ---> Zn + 2Li(C2H3O2)
Li- 2 |Li- 2
Zn- 1 | Zn- 1
C2H3O2- 2 |C2H3O2- 2
2Li + Zn(C2H3O2)2 ---> Zn + 2Li(C2H3O2)
Copper + Aluminum Sulfate ---> No Reaction
This reaction cant happen because if you look at the chart you'll see that Copper is below Aluminum. Reactions only work if the one you're swapping in is higher on the chart than the one you're swapping out.
4. Double Replacement- Two compounds react to form two new compound
Compound + Compound ---> Compound + Compound
AB + CD ---> AD + BC
You do not use the activity series sheet for these reactions.
Ex. Cu2(SO4) + Be(C2O4) --->Cu2(C2O4) + Be(SO4)
Cu- 2 |Cu- 2
SO4- 1 |SO4- 1
Be- 1 |Be- 1
C2O4- 1 |C2O4- 1
Already Balanced
A Neutralization reaction is a type of Double Replacement Reaction, where a reaction occurs between an acid and a base. (Base- Metal hydroxide)
Water will always be a product in a neutralization reaction.
Ex. Al(OH)3 + HNO3 ---> Al(NO3)3 + H(OH)
Al- 1 |Al- 1
OH- 3 |OH- 1
H- 1 |H-1
NO3- 1 |NO3- 9
Al(OH)3 + 3HNO3 ---> Al(NO3)3 + 3H(OH)
Al- 1 |Al- 1
OH- 3 |OH- 3
H- 3 |H-3
NO3- 9 |NO3- 9
Al(OH)3 + 3HNO3 ---> Al(NO3)3 + 3H(OH)
Water will always be a product in a neutralization reaction.
Ex. Al(OH)3 + HNO3 ---> Al(NO3)3 + H(OH)
Al- 1 |Al- 1
OH- 3 |OH- 1
H- 1 |H-1
NO3- 1 |NO3- 9
Al(OH)3 + 3HNO3 ---> Al(NO3)3 + 3H(OH)
Al- 1 |Al- 1
OH- 3 |OH- 3
H- 3 |H-3
NO3- 9 |NO3- 9
Al(OH)3 + 3HNO3 ---> Al(NO3)3 + 3H(OH)
5. Combustion- A reaction with oxygen.
If Your Reactants Contain:
C H S N |
Your Products Will Be:
CO2 H2O SO2 N2 |
Ex. CH4 + O2 ---> CO2 + H2O
C- 1 |C-1 H- 4 |H- 2 O- 2 |O- 2+1 CH4 + 2O2 ---> CO2 + 2H2O C- 1 |C-1 H- 4 |H- 4 O- 4 |O- 2+2 CH4 + 2O2 ---> CO2 + 2H2O |
Predicting Products
E= Element C= Compound
Synthesis- E + E = C Double Replacement- Positive Ions
Decomposition- C= E + E Combustion- If oxygen is involved in reaction
Single Replacement- E + C = E + C
E= Element C= Compound
Synthesis- E + E = C Double Replacement- Positive Ions
Decomposition- C= E + E Combustion- If oxygen is involved in reaction
Single Replacement- E + C = E + C
Reaction Rates
Reaction rates measure the progress of chemical reactions over time. They can occur very quickly, or very slowly. Fast reactions may involve explosions, while the slower reactions occur more gradually. Sort of like bananas getting ripe, (Fun Fact: I just ate a banana at 1 am) you can see the bananas turn from a greenish color to brown. Reaction rates can also measure the time it takes for the reactants of something to change into the products. They tell how fast energy is being absorbed and released.
Chemical Reactions involve the collisions of reactants.
Reaction rates measure the progress of chemical reactions over time. They can occur very quickly, or very slowly. Fast reactions may involve explosions, while the slower reactions occur more gradually. Sort of like bananas getting ripe, (Fun Fact: I just ate a banana at 1 am) you can see the bananas turn from a greenish color to brown. Reaction rates can also measure the time it takes for the reactants of something to change into the products. They tell how fast energy is being absorbed and released.
Chemical Reactions involve the collisions of reactants.
Increase Reaction Rate
Rapid Particle Collisions Increase in Temperature Larger Surface Area and Smaller Reactant Particles Stirring Increase in Concentration |
Decrease Reaction Rate
Less Frequent Particle Collisions |
Concentration is how many reactant particles are in a given volume. The concentration of a gas will increase with a greater pressure.
Catalysts are substances that speed up reactions without actually chemically changing itself. They work by providing a surface are to reactants helping them come together quicker. This also lowers the activation energy, reducing the amount of energy needed for the reaction to happen.
Equilibrium of a system is a state in which forward and reverse problems happen at the same rate. A system that has no overall change in amounts is said to be in equilibrium, aka balanced.
Reversible Reactions occur when the reactants change into products, and then change back into reactants at the same time. A double arrow (<--->) is used in chemical formulas to show reversible chemical reactions.
Chemical Equilibrium is reached if a chemical reaction doesn't go to completion. Chemical Equilibria is similar to reaction rate sin the way they can change depending on temperature, concentration, and pressure.
Fast Forward Reactions, left to right, and Reverse Reactions, right to left, are dependent on what side of the formula the change is being applied to. They are also both dependent on what type of change is involved. If the change is being applied to the right side of the equation, the product side, then a reverse reaction will occur. If the change is being applied to the left side, the reactant side, then a fast forward reaction will occur.
Catalysts are substances that speed up reactions without actually chemically changing itself. They work by providing a surface are to reactants helping them come together quicker. This also lowers the activation energy, reducing the amount of energy needed for the reaction to happen.
Equilibrium of a system is a state in which forward and reverse problems happen at the same rate. A system that has no overall change in amounts is said to be in equilibrium, aka balanced.
Reversible Reactions occur when the reactants change into products, and then change back into reactants at the same time. A double arrow (<--->) is used in chemical formulas to show reversible chemical reactions.
Chemical Equilibrium is reached if a chemical reaction doesn't go to completion. Chemical Equilibria is similar to reaction rate sin the way they can change depending on temperature, concentration, and pressure.
Fast Forward Reactions, left to right, and Reverse Reactions, right to left, are dependent on what side of the formula the change is being applied to. They are also both dependent on what type of change is involved. If the change is being applied to the right side of the equation, the product side, then a reverse reaction will occur. If the change is being applied to the left side, the reactant side, then a fast forward reaction will occur.
Activity Series
The activity series is just a list of substances ranked in order of their relative reactivity.
Ex. Barium, Ba, is higher up on the list than Bismuth, Bi. that means Barium is more active than Bismuth.
The activity series is just a list of substances ranked in order of their relative reactivity.
Ex. Barium, Ba, is higher up on the list than Bismuth, Bi. that means Barium is more active than Bismuth.
Solubility Rules
Soluble:
All Group 1 salts, Nitrates, Ammonium, and Acetates All Chlorides, Bromides, and Iodides, except for Silver, Lead, and Mercury(I) All Fluorides except for Calcium, Strontium, Barium, Mercury, Silver, and Lead(II), and Iron(III) All Sulfates except Calcium, Strontium, Barium, Mercury, Lead(II), and Silver |
Insoluble (0.10 M or greater):
All Carbonates and Phosphates except Group 1 and Ammonium All Hydroxides except Group 1, Strontium, Barium, and Ammonium All Sulfides except Group 1, 2, and Ammonium. All Oxides except Group 1 |