When solid magnesium nitride reacts with water the reaction produces solid magnesium hydroxide and ammonia gas. 26.0 grams of magnesium nitride are reacted with 17.6 grams of water.
1. How many grams of magnesium nitride will remain after reaction is complete?
2. How many grams of water will reamain after reaction is complete?
3. How many grams of magnesium hydroxide will remain after reaction is complete?
4. How many grams of ammonia gas will remain after reaction is complete?
This is a limiting reagent (LR) problem.
Mg3N2 + 6HOH --> 3Mg(OH)2 + 2NH3
mols Mg3N2 = g/molar mass = ?
mols H2O = g/molar mass = ?
Using the coefficients in the balanced equation, convert mols Mg3N2 to mols Mg(OH)2
Do the same to convert mols H2O to mols Mg(OH)2. It is likely that you will get two answers for mols Mg(OH)2 formed. In LR problems, the SMALLER number of mols produced is correct and the reagent providing that number (in this case either Mg3N2 or H2O). The other reagent we will call OR.
3. g Mg(OH)3 formed (remaining)= mols Mg(OH)2 x molar mass = ?
4. Using the coefficients in the balanced equatioin, convert mols of the LR to mols NH3. Then g NH3 formed (remaining) = mols NH3 x molar mass NH3 = ?
1 and 2. The LR will have zero mols remaining and zero grams remaining because all of it will be used. That's why it is called the LR. To find the other one, Convert mols LR to mols OR used. Suibtract from mols OR initially to find mols OR remaining. Then grams = mols x molar mass.
Post your work if you get stuck.
To answer these questions, we need to determine the limiting reactant in the reaction. The limiting reactant is the one that runs out first and determines the maximum amount of product that can be formed.
1. To find out how many grams of magnesium nitride will remain after the reaction, we first need to calculate the moles of magnesium nitride and water.
Moles of magnesium nitride = mass of magnesium nitride / molar mass of magnesium nitride
Moles of water = mass of water / molar mass of water
The molar mass of magnesium nitride (Mg3N2) is calculated by adding the atomic masses of magnesium (24.31 g/mol) and nitrogen (14.01 g/mol):
Molar mass of magnesium nitride = 3 * (molar mass of magnesium) + 2 * (molar mass of nitrogen)
The molar mass of water (H2O) is calculated by adding the atomic masses of hydrogen (1.01 g/mol) and oxygen (16.00 g/mol):
Molar mass of water = 2 * (molar mass of hydrogen) + (molar mass of oxygen)
2. Next, we need to determine the stoichiometry of the reaction. The balanced chemical equation for the reaction is:
3 Mg3N2 + 6 H2O -> 6 Mg(OH)2 + 2 NH3
From the balanced equation, we can see that 3 moles of magnesium nitride react with 6 moles of water to produce 6 moles of magnesium hydroxide and 2 moles of ammonia gas.
3. Now, we can calculate the moles of magnesium nitride and water that react. Assuming complete reaction:
Moles of magnesium nitride reacted = moles of water reacted = min(moles of magnesium nitride, moles of water)
This is because the balanced equation shows a 1:1 molar ratio between magnesium nitride and water.
4. To find the maximum amount of product formed, we need to determine the limiting reactant. The limiting reactant is the one that produces fewer moles of product.
To do this, we compare the moles of magnesium nitride and water reacted. Whichever has the lowest value is the limiting reactant.
5. Once we know the limiting reactant, we can use the balanced equation to calculate the moles of magnesium hydroxide and ammonia gas formed.
Moles of magnesium hydroxide = 6 * moles of limiting reactant
Moles of ammonia gas = 2 * moles of limiting reactant
6. Finally, we can calculate the grams of each substance using the molar mass.
Grams of magnesium nitride remaining = (moles of magnesium nitride - moles of limiting reactant) * molar mass of magnesium nitride
Grams of water remaining = (moles of water - moles of limiting reactant) * molar mass of water
Grams of magnesium hydroxide remaining = moles of magnesium hydroxide * molar mass of magnesium hydroxide
Grams of ammonia gas remaining = moles of ammonia gas * molar mass of ammonia gas
By following these steps, you will be able to determine the grams of each substance remaining after the reaction is complete.