A mass of 37.5 grams of mercury oxide is decomposed by heating. The reaction is 2HgO > 2Hg + O2. A. How many moles of mercury oxide is decomposed? B. How many moles of oxygen are prepared? C. How many grams of oxygen are prepared?
To solve this problem, we need to use the given mass of mercury oxide to determine the number of moles of mercury oxide, then use the stoichiometric relationship between mercury oxide and oxygen to find the number of moles of oxygen, and finally convert the moles of oxygen to grams of oxygen.
A. To find the number of moles of mercury oxide decomposed, we need to use the molar mass of mercury oxide. The molar mass of mercury (Hg) is 200.59 g/mol, and oxygen (O) is 16.00 g/mol. Since one mercury atom (Hg) combines with one oxygen atom (O) to form mercury oxide (HgO), the molar mass of mercury oxide (HgO) is:
Molar mass of HgO = (1 mol of Hg x molar mass of Hg) + (1 mol of O x molar mass of O)
= (1 mol x 200.59 g/mol) + (1 mol x 16.00 g/mol)
= 200.59 g/mol + 16.00 g/mol
= 216.59 g/mol
Now, we can calculate the number of moles of mercury oxide using the equation:
Number of moles of HgO = Mass of HgO / Molar mass of HgO
Substituting the values into the equation:
Number of moles of HgO = 37.5 g / 216.59 g/mol
≈ 0.173 moles of HgO
Therefore, approximately 0.173 moles of mercury oxide are decomposed.
B. According to the balanced chemical equation, the stoichiometric ratio between mercury oxide (HgO) and oxygen (O2) is 2:1. This means that for every 2 moles of mercury oxide decomposed, 1 mole of oxygen is produced. Therefore, the number of moles of oxygen produced can be calculated using the equation:
Number of moles of O2 = (Number of moles of HgO) / 2
Substituting the value of the number of moles of HgO:
Number of moles of O2 = 0.173 moles / 2
= 0.087 moles of O2
Therefore, approximately 0.087 moles of oxygen are prepared.
C. To find the grams of oxygen prepared, we need to use the molar mass of oxygen.
Molar mass of O2 = 2 x molar mass of O
= 2 x 16.00 g/mol
= 32.00 g/mol
Now, we can calculate the grams of oxygen using the equation:
Mass of O2 = Number of moles of O2 x Molar mass of O2
Substituting the value of the number of moles of O2:
Mass of O2 = 0.087 moles x 32.00 g/mol
= 2.784 grams of O2
Therefore, approximately 2.784 grams of oxygen are prepared.
2HgO ==> 2Hg + O2
mols HgO = grams HgO/molar mass HgO = ?
Then from the equation you get 2 mols Hg for every 2 mols HgO initially so mols Hg =- mols HgO.
mols O2 will be 1/2 mols HgO.
grams O2 = mols O2 x molar mass O2 = ?
Post your work if you get stuck.