Magnesium metal burns in oxygen to form magnesium
oxide, MgO.
(a) Write a balanced equation for the reaction
Why is it 2Mg+O2->2MgO
and not Mg+O->MgO
because oxygen comes in O2 molecules, not single-atom units.
Remember the mnemonic of "Have No Fear Of Ice Cold Beer".
hydrogen
nitrogen
fluorine
oxygen
iodine
chlorine
bromine
and add their cousins of P4 and S8.
The other elements are monatomic at room T and P.
The balanced equation for the reaction between magnesium metal (Mg) and oxygen (O2) to form magnesium oxide (MgO) is indeed 2Mg + O2 → 2MgO.
The reason for this balanced equation is based on the law of conservation of mass. The law states that matter cannot be created or destroyed in a chemical reaction. In other words, the number of each type of atom on both sides of the equation must remain the same.
In the case of magnesium burning in oxygen, the reaction involves the formation of magnesium oxide, which consists of one magnesium atom (Mg) and one oxygen atom (O). Therefore, we need to have equal numbers of magnesium and oxygen atoms on both sides of the equation.
If we were to write the equation as Mg + O → MgO, we would have one magnesium atom on the left side but only one oxygen atom on the right side. This means that the equation is unbalanced because there is an unequal number of atoms on both sides.
To balance the equation, we need to multiply MgO by 2 on the right side to have an equal number of oxygen atoms. This would give us 2Mg + O2 → 2MgO, where we have two magnesium atoms on the left side and two of each atom on the right side. This balanced equation satisfies the law of conservation of mass.
To understand why the balanced equation for the reaction between magnesium and oxygen is 2Mg + O2 -> 2MgO, we need to consider the law of conservation of mass. According to this law, matter is neither created nor destroyed in a chemical reaction, so the number of atoms of each element must be the same on both sides of the equation.
Let's break down each side of the equation:
On the left side of the equation, there are 2 magnesium atoms (2Mg) reacting with 1 molecule of oxygen (O2). Remember that in chemistry, we often use molecular formulas to represent elements when they are chemically bound together. In this case, oxygen naturally exists as O2, meaning it is made up of two oxygen atoms bonded together.
On the right side of the equation, the product is magnesium oxide (MgO). In each magnesium oxide molecule (MgO), there is one magnesium atom and one oxygen atom.
Now, let's compare the number of atoms on each side of the equation:
Left side: 2 magnesium atoms + 2 oxygen atoms
Right side: 2 magnesium atoms + 2 oxygen atoms
By balancing the equation, we ensure that the number of atoms of each element is equal on both sides. If we only had Mg + O -> MgO, we would have the same number of magnesium atoms on both sides (1), but the number of oxygen atoms would not match (1 on the left side and 2 on the right side). Therefore, the equation needs to be balanced as 2Mg + O2 -> 2MgO to satisfy the law of conservation of mass.