Use your knowledge of the law of conservation of mass to answer the following question: In the lab, a student reacts lithium with oxygen to produce lithium oxide. (Lithium + Oxygen -----> Lithium Oxide) How much lithium will be needed to react with 5.4 grams of oxygen to produce 24.6 grams of lithium oxide?
write the balanced equation
see how many moles of Li2O per mole of Li
convert grams to moles.
do the math.
The numbers in the problem are not correct; therefore, using the law of conservation of mass doesn't work. For example, 5.4 g O2 will produce 10.08 g Li2O. If the problem were quoted properly for conservation of mass, it would be using 5.4 g O2 how much Li would be required to produce 10.08 g Li2O. Then you would do this:
..................4Li + O2 ==> 2Li2O
.....................x.....5.4.........10.08
Then x + 5.4 = 10.8 and
x = 10.8 - 5.4 =4.68
Use the method shown by oobleck, although not using the law of conservation of mass, that 4.68 is correct; i.e.,
mols O2 = 5.4/32 = ?
mols Li = 4*mols O2
g Li = mols Li x atomic mass Li = 4.68
To answer this question, we can use the law of conservation of mass, which states that mass is neither created nor destroyed during a chemical reaction. This means that the total mass of the reactants (in this case, lithium and oxygen) should equal the total mass of the products (lithium oxide).
First, we need to determine the molar mass of oxygen (O), lithium (Li), and lithium oxide (Li2O). The molar mass of an element is the mass of one mole of that substance. We can find the molar mass of an element by looking at the periodic table.
The molar mass of oxygen (O) is approximately 16 g/mol.
The molar mass of lithium (Li) is approximately 6.94 g/mol.
The molar mass of lithium oxide (Li2O) is the sum of the molar masses of lithium and oxygen, which is approximately (2 * 6.94) + 16 = 29.88 g/mol.
Now, let's calculate the number of moles of oxygen (O) and lithium oxide (Li2O) using their given masses.
Number of moles of oxygen (O):
moles = mass / molar mass
moles of O = 5.4 g / 16 g/mol ≈ 0.3375 mol
Number of moles of lithium oxide (Li2O):
moles = mass / molar mass
moles of Li2O = 24.6 g / 29.88 g/mol ≈ 0.8233 mol
According to the balanced chemical equation, the ratio between the number of moles of oxygen and lithium oxide is 1:1.
Since the reaction requires one mole of oxygen to produce one mole of lithium oxide, the number of moles of lithium required will be equal to the number of moles of oxygen.
Number of moles of lithium (Li) = 0.3375 mol
Finally, we can calculate the mass of lithium needed by multiplying the number of moles of lithium by its molar mass.
Mass of lithium (Li) = moles of Li * molar mass of Li
Mass of Li = 0.3375 mol * 6.94 g/mol ≈ 2.34 grams
Therefore, approximately 2.34 grams of lithium will be needed to react with 5.4 grams of oxygen to produce 24.6 grams of lithium oxide.