Antoine Lavoisier found that "The law of conservation of mass, or principle of mass conservation, states that for any system closed to all transfers of matter and energy (both of which have mass), the mass of the system must remain constant over time, as system mass cannot change quantity if it is not added or removed."
This means that atoms in an object can't be withdrawn or eradicated, but they can be moved around and changed into different particles.
In an equation, the mass of reactants must equal the mass of the products.
This means that atoms in an object can't be withdrawn or eradicated, but they can be moved around and changed into different particles.
In an equation, the mass of reactants must equal the mass of the products.
Using the concept of the Law of Conservation of Mass, you can balance chemical equations which basically means that the number of element on one side must equal to the corresponding element on the other side.
Take for K2CO3 → K2O + CO2 for example:
↗
(the subscripts tell you how much of that element there is)
#K_2_
#C_1_
#O_3_
Now check the right side to make sure they all have the same amount of elements!
#K_2_
#C_1_
#O_3_
Since both sides have the same amount of element, the equation is balanced.
Now let's try one that isn't already balanced:
SiI4 + Mg → Si + Mgl2
Check the left side first!
#Si_1_
#I_4_
#Mg_1_
Now check the right side:
#Si_1_
#I_2_
#Mg_1_
Because this equation isn't balanced, we have to write coefficients on the side of the elements.
SiI4 + 2 Mg → Si + 2 Mgl2
By adding those two's (the coefficients), the number of elements change. You now multiply the subscripts with the coefficients to get the new number of elements which now becomes:
#Si_1_
#I_4_
#Mg_2_
Now the right side:
#Si_1_
#I_4_
#Mg_2_
The equation is now balanced! The same can be done for the following equations:
3 NH4Cl + AlPO4 → (NH4)3PO4 + AlCl3
K3PO4 + 3 HCl → 3 KCl + H3PO4
2 Na + 2 HNO3 → 2 NaNO3 + H2
Take for K2CO3 → K2O + CO2 for example:
↗
(the subscripts tell you how much of that element there is)
#K_2_
#C_1_
#O_3_
Now check the right side to make sure they all have the same amount of elements!
#K_2_
#C_1_
#O_3_
Since both sides have the same amount of element, the equation is balanced.
Now let's try one that isn't already balanced:
SiI4 + Mg → Si + Mgl2
Check the left side first!
#Si_1_
#I_4_
#Mg_1_
Now check the right side:
#Si_1_
#I_2_
#Mg_1_
Because this equation isn't balanced, we have to write coefficients on the side of the elements.
SiI4 + 2 Mg → Si + 2 Mgl2
By adding those two's (the coefficients), the number of elements change. You now multiply the subscripts with the coefficients to get the new number of elements which now becomes:
#Si_1_
#I_4_
#Mg_2_
Now the right side:
#Si_1_
#I_4_
#Mg_2_
The equation is now balanced! The same can be done for the following equations:
- NH4Cl + AlPO4 → (NH4)3PO4 + AlCl3
3 NH4Cl + AlPO4 → (NH4)3PO4 + AlCl3
- K3PO4 + HCl → KCl + H3PO4
K3PO4 + 3 HCl → 3 KCl + H3PO4
- Na + HNO3 → NaNO3 + H2
2 Na + 2 HNO3 → 2 NaNO3 + H2