Magnesium reacts with oxygen to form magnesium oxide according to the following equation:
2Mg(s) + O2(g) ==> 2MGO(s)
If 0.81 grams of magnesium oxide are formed, how many grams of oxygen reacted?
MGO and MgO are not the same.
1. You have the balanced equation.
2. Convert 0.81 grams MgO to moles. moles = grams/molar mass.
3. Using the coefficients in the balanced equation, convert moles MgO to moles O2.
4. Convert moles O2 to grams. g = mols x molar mass.
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Nine
To find out how many grams of oxygen reacted, you need to use stoichiometry and the given amount of magnesium oxide formed.
Here's how you can solve the problem step by step:
1. Determine the molar mass of magnesium oxide (MgO):
- Magnesium (Mg) has a molar mass of 24.31 g/mol.
- Oxygen (O) has a molar mass of 16.00 g/mol.
- Adding the molar masses together, we get: 24.31 g/mol + 16.00 g/mol = 40.31 g/mol.
2. Convert the given amount of magnesium oxide (0.81 grams) to moles:
- Divide the given amount by the molar mass of magnesium oxide:
0.81 g / 40.31 g/mol = 0.02 mol.
3. Use the balanced equation to determine the mole ratio between oxygen and magnesium oxide:
According to the equation: 2Mg(s) + O2(g) → 2MgO(s),
the ratio is 1 mole of oxygen reacts with 2 moles of magnesium oxide.
4. Use the mole ratio to calculate the number of moles of oxygen:
Multiply the number of moles of magnesium oxide by the mole ratio:
0.02 mol (oxygen) = 0.02 mol (magnesium oxide) * (1 mol O2 / 2 mol MgO).
5. Convert moles of oxygen to grams:
Multiply the number of moles of oxygen by the molar mass of oxygen:
0.02 mol * 32.00 g/mol = 0.64 grams.
Therefore, 0.64 grams of oxygen reacted to form 0.81 grams of magnesium oxide.