if 14.0 g of aluminium reacts with excess sulfuric acid to produce 75.26 g of aluminium sulfate, what is the percent yield?
1 answer:
Taking into account definition of percent yield, the percent yield for the reaction is 84.88%.
<h3>Reaction stoichiometry</h3>In first place, the balanced reaction is:
2 Al + 3 H₂SO₄ → Al₂(SO₄)₃ + 3 H₂
By reaction stoichiometry (that is, the relationship between the amount of reagents and products in a chemical reaction), the following amounts of moles of each compound participate in the reaction:
- Al: 2 moles
- H₂SO₄: 3 moles
- Al₂(SO₄)₃. 1 mole
- H₂: 3 moles
The molar mass of the compounds is:
- Al: 27 g/mole
- H₂SO₄: 98 g/mole
- Al₂(SO₄)₃: 342 g/mole
- H₂: 2 g/mole
Then, by reaction stoichiometry, the following mass quantities of each compound participate in the reaction:
- Al: 2 moles ×27 g/mole= 54 grams
- H₂SO₄: 3 moles ×98 g/mole= 294 grams
- Al₂(SO₄)₃: 1 mole ×342 g/mole= 342 grams
- H₂: 3 moles ×2 g/mole= 6 grams
The following rule of three can be applied: if by reaction stoichiometry 54 grams of aluminium form 342 grams of aluminium sulfate, 14 grams of aluminium form how much mass of aluminium sulfate?
<u><em>mass of aluminium sulfate= 88.67 grams</em></u>
Then, 88.67 grams of aluminium sulfate can be produced if 14.0 g of aluminium reacts with excess sulfuric acid.
<h3>Percent yield</h3>The percent yield is the ratio of the actual return to the theoretical return expressed as a percentage.
The percent yield is calculated as the experimental yield divided by the theoretical yield multiplied by 100%:
where the theoretical yield is the amount of product acquired through the complete conversion of all reagents in the final product, that is, it is the maximum amount of product that could be formed from the given amounts of reagents.
<h3>Percent yield for the reaction in this case</h3>In this case, you know:
- actual yield= 75.26 grams
- theorical yield= 88.67 grams
Replacing in the definition of percent yields:
Solving:
<u><em>percent yield= 84.88%</em></u>
Finally, the percent yield for the reaction is 84.88%.
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Answer:
- Nitrogen has four pairs of electrons: 3 bonds and 1 lone pair in the valence shell;
- Electrons repel one another based on the VSEPR theory;
- Nitrogen has a total of 7 protons (its atomic number is 7) in its nucleus.
Explanation:
The shape and the bond orientation of molecules and ions are both explained by the valences shell electron pair repulsion theory (VSEPR).
Ammonia, , is a molecule which contains three N-H bonds, as well as one lone pair on nitrogen. According to the VSEPR theory, molecules try to acquire a shape which would minimize the repulsion exhibited by the electron clouds present, that is, between the bonding (shared in a bond) and non-bonding (lone pair) electrons.
In VSEPR, our main step is to calculate the steric number, this is the sum of the number of bonds (ignoring the multiplicity of any bond) and the lone pairs on a central atom. In ammonia, we have 3 bonds and 1 lone pair, totaling to a steric number of 4. A steric number of 4 without any lone pairs on a central atom and just bonds would yield a tetrahedral shape with bond angles of .
Now, in this case, since we have a lone pair instead of a bond, it is repelling stronger decreasing the bond angles to about .
The greater the number of lone pairs, the lower the angle becomes.
To summarize:
- Nitrogen has four pairs of electrons: 3 bonds and 1 lone pair in the valence shell;
- Electrons repel one another based on the VSEPR theory;
- Nitrogen has a total of 7 protons (its atomic number is 7) in its nucleus.