Consider the reaction of magnesium metal with hydochloric acid to produce magnesium chloride and hydrogen gas. If 3.85 mol Mg and 3.85 mol of HCl are reacted, how many mol of oxygen are left over?
I balanced the equation and got Mg(OH)2+2HCl=MgCl2+2H2O.
Can you please walk me through the steps and not just give the answer?
Your equation is not correct. The correct one is Mg + 2HCl ==> H2 + MgCl2
You have mixed up two problems. There is no oxygen in this problem.
Sure! To find out how many moles of oxygen are left over in the reaction, we first need to determine the limiting reactant. The limiting reactant is the one that will be completely consumed in the reaction, and it determines the maximum amount of product that can be formed.
In this case, we have 3.85 mol of magnesium (Mg) and 3.85 mol of hydrochloric acid (HCl). However, to balance the equation correctly, we need to use Mg and H2O instead of Mg(OH)2 as you have written.
The balanced equation for the reaction is: Mg + 2HCl → MgCl2 + H2.
To determine the limiting reactant, we can compare the stoichiometric ratio between Mg and HCl. From the balanced equation, we can see that the ratio is 1:2, meaning that for every 1 mol of Mg, we need 2 mol of HCl.
So, let's consider the amount of HCl needed to react with 3.85 mol of Mg: 3.85 mol of Mg x (2 mol HCl / 1 mol Mg) = 7.7 mol HCl.
Since we only have 3.85 mol of HCl, which is less than the required amount, it is the limiting reactant. This means that all of the HCl will be consumed in the reaction, and the amount of Mg remaining will determine how much oxygen is left over.
To find the amount of Mg remaining, we can use the stoichiometric ratio between Mg and H2O. From the balanced equation, we can see that the ratio is 1:1, meaning that for every 1 mol of Mg, we will get 1 mol of H2O.
Since all the HCl is consumed, we know that 3.85 mol of H2O is produced. Therefore, the amount of Mg remaining is also 3.85 mol.
Now, to find the amount of oxygen (O2) left over, we need to determine the moles of oxygen produced from the consumed H2O. From the balanced equation, we can see that 1 mol of H2O produces 1 mol of O2.
Since we have 3.85 mol of H2O, we also have 3.85 mol of O2.
Therefore, the answer is that there are 3.85 mol of oxygen left over in the reaction.
Remember, the key steps to solve this type of problem are:
1. Balance the equation correctly.
2. Determine the limiting reactant by comparing the stoichiometric ratio between reactants.
3. Use the limiting reactant to determine the amount of the desired product.
4. Calculate the excess reactant if needed.
5. Convert the amount of desired product or excess reactant to any other requested unit if necessary.