1)
MgO (s) + 2H (aq) -> Mg+2 (aq) + H2O (l)
2)
Mg+2 (aq) + H2 (g)-> Mg(s) + 2H+ (l)
3) equation 1+ equation 2 =
MgO (s) + H2 (g) -> Mg (s) + H2O (l)
is it correct?
if so, i need to write an expression which could be used to obtain the heat of formation of magnesium oxide (delta Hf MgO)
thanks
At first glance it looks OK except equation 1 should have + charge on the H^+.
But if you want to write an expression for delta Hf MgO, where is the oxygen?.
You want Mg + 1/2 O2 ==> MgO
The equation you have written is not correct. When you combine the two given equations, the overall reaction should be balanced. By doing so, the correct equation becomes:
2MgO (s) + 2H+ (aq) + 2H2 (g) -> 2Mg (s) + 4H2O (l)
To determine the heat of formation of magnesium oxide (𝛥Hf MgO), you need to use the Hess's Law. This law states that the overall enthalpy change for a reaction is the sum of the enthalpy changes for the individual steps or reactions involved.
One method to obtain the heat of formation of magnesium oxide is by the use of calorimetry. This involves measuring the heat released or absorbed during the combustion of magnesium to form magnesium oxide. The heat released can be measured using a calorimeter, and then the heat of formation can be calculated using the stoichiometry of the reaction and the known enthalpies of formation of the other substances involved.
Another method is to calculate the heat of formation using tabulated values of enthalpies of formation. The heat of formation of magnesium oxide (𝛥Hf MgO) can be determined using the enthalpies of formation of magnesium (𝛥Hf Mg) and water (𝛥Hf H2O). The equation would be:
𝛥Hf MgO = [𝛥Hf Mg + 2𝛥Hf H2O] - [2𝛥Hf MgO]
Please note that the values of enthalpies of formation need to be obtained from a reliable source, such as a thermochemical database.
To determine the correct balanced equation, let's first analyze the given chemical equations:
1) MgO (s) + 2H (aq) -> Mg+2 (aq) + H2O (l)
This equation shows the reaction between solid magnesium oxide (MgO) and aqueous hydrogen (H) to form aqueous magnesium ions (Mg+2) and liquid water (H2O).
2) Mg+2 (aq) + H2 (g) -> Mg(s) + 2H+ (l)
This equation illustrates the reaction between aqueous magnesium ions (Mg+2) and gaseous hydrogen (H2) to produce solid magnesium (Mg) and aqueous hydrogen ions (H+).
Now, if we add these two equations together, we get:
MgO (s) + 2H (aq) + Mg+2 (aq) + H2 (g) -> Mg(s) + 2H+ (l) + H2O (l)
However, we need to cancel out any common species present on both sides of the equation. In this case, H+ appears on both sides, so we can eliminate them by canceling them out. Additionally, we need to eliminate the spectator ions (Mg+2) that do not participate in the overall reaction.
By doing this, we end up with the simplified balanced equation:
MgO (s) + H2 (g) -> Mg (s) + H2O (l)
So, your equation #3, MgO (s) + H2 (g) -> Mg (s) + H2O (l), is correct.
To obtain the heat of formation (ΔHf) of magnesium oxide (MgO), you will need to calculate the enthalpy change (∆H) for this reaction. The heat of formation is defined as the enthalpy change when one mole of a compound is formed from its constituent elements in their standard states.
To calculate the heat of formation, you would typically use thermodynamic data or Hess's law. Thermodynamic data provides the standard enthalpy change for each substance involved in the reaction, while Hess's law allows you to calculate the overall enthalpy change by combining known enthalpy changes of other reactions.
Alternatively, experimental methods like calorimetry can also be implemented to determine the heat of formation directly.
Please note that the ∆Hf value for magnesium oxide is typically provided in reference books or other reliable sources.