For the question(s) that follow, consider the following equation.
2Mg + O2�¨ 2MgO
How many grams of MgO are produced when 40.0 grams of O2 react completely with Mg?
Convert 40 g oxygen to moles. moles = grams/molar mass
Using the coefficients in the balanced equation, convert moles oxygen to moles MgO.
Convert moles MgO to grams. g = mols x molar mass.
To determine the grams of MgO produced, we need to use stoichiometry. Stoichiometry allows us to calculate the relationship between reactants and products in a chemical equation.
First, let's determine the molar masses of Mg, O2, and MgO:
- The molar mass of Mg is 24.31 g/mol.
- The molar mass of O2 is 32.00 g/mol.
- The molar mass of MgO is 40.31 g/mol.
Next, we need to determine the number of moles of O2:
- Moles = Mass / Molar mass
- Moles of O2 = 40.0 g / 32.00 g/mol = 1.25 mol
According to the balanced equation, the stoichiometric ratio between O2 and MgO is 1:2. This means that for every 1 mole of O2, 2 moles of MgO are produced.
Since we have 1.25 moles of O2, we can use the stoichiometric ratio to find the moles of MgO produced:
- Moles of MgO = Moles of O2 x (2 moles of MgO / 1 mole of O2)
- Moles of MgO = 1.25 mol x (2 mol MgO / 1 mol O2) = 2.50 mol
Finally, we can calculate the grams of MgO produced:
- Mass = Moles x Molar mass
- Mass of MgO = 2.50 mol x 40.31 g/mol = 100.78 g
Therefore, 100.78 grams of MgO are produced when 40.0 grams of O2 react completely with Mg.
To find the number of grams of MgO produced when 40.0 grams of O2 react completely with Mg, we need to use stoichiometry, which is a way to relate the amounts of substances in a chemical reaction.
Step 1: Calculate the molar mass of O2.
The molar mass of O2 is 2 * atomic mass of oxygen. Since oxygen has an atomic mass of approximately 16, the molar mass of O2 is 2 * 16 = 32 g/mol.
Step 2: Convert the given mass of O2 to moles.
To convert grams to moles, we divide the given mass by the molar mass. In this case, we divide 40.0 grams by 32 g/mol to obtain 1.25 moles of O2.
Step 3: Use the balanced equation to determine the moles of MgO produced.
From the balanced equation 2Mg + O2 → 2MgO, we can see that the ratio of moles of O2 to moles of MgO is 1:2. Therefore, if we have 1.25 moles of O2, we will have 2 * 1.25 = 2.50 moles of MgO produced.
Step 4: Calculate the molar mass of MgO.
The molar mass of MgO can be calculated by adding the atomic masses of magnesium and oxygen. The atomic mass of Mg is approximately 24, and the atomic mass of O is approximately 16. So, the molar mass of MgO is 24 + 16 = 40 g/mol.
Step 5: Convert moles of MgO to grams.
To convert moles to grams, we multiply the moles of MgO by its molar mass. In this case, we multiply 2.50 moles by 40 g/mol to obtain 100 grams of MgO.
Therefore, when 40.0 grams of O2 react completely with Mg, 100 grams of MgO are produced.