Chapter 7: Problem 15
Calculate the molar mass for each of the following: a. \(\mathrm{AlF}_{3}\) b. \(\mathrm{C}_{2} \mathrm{H}_{4} \mathrm{Cl}_{2}\) c. \(\mathrm{SnF}_{2}\)
Short Answer
Expert verified
a. 83.98 g/mol, b. 98.96 g/mol, c. 156.71 g/mol
Step by step solution
01
Identify Atomic Masses
Gather the atomic masses of the individual elements from the periodic table:- Aluminum (Al): 26.98 g/mol- Fluorine (F): 19.00 g/mol- Carbon (C): 12.01 g/mol- Hydrogen (H): 1.01 g/mol- Chlorine (Cl): 35.45 g/mol- Tin (Sn): 118.71 g/mol
02
Calculate Molar Mass of \(\mathrm{AlF}_3\)
Use the formula to sum the products of each element's atomic mass and its subscript in the compound. For \(\mathrm{AlF}_3\):\[ M(\mathrm{AlF}_3) = 1 \times M(\mathrm{Al}) + 3 \times M(\mathrm{F}) \]\[ = 1 \times 26.98 \text{ g/mol} + 3 \times 19.00 \text{ g/mol} \]\[ = 26.98 + 57.00 \]\[ = 83.98 \text{ g/mol} \]
03
Calculate Molar Mass of \(\mathrm{C}_2 \mathrm{H}_4 \mathrm{Cl}_2\)
Sum the products of each element's atomic mass and its subscript in the compound. For \(\mathrm{C}_2 \mathrm{H}_4 \mathrm{Cl}_2\):\[ M(\mathrm{C}_2 \mathrm{H}_4 \mathrm{Cl}_2) = 2 \times M(\mathrm{C}) + 4 \times M(\mathrm{H}) + 2 \times M(\mathrm{Cl}) \]\[ = 2 \times 12.01 \text{ g/mol} + 4 \times 1.01 \text{ g/mol} + 2 \times 35.45 \text{ g/mol} \]\[ = 24.02 + 4.04 + 70.90 \]\[ = 98.96 \text{ g/mol} \]
04
Calculate Molar Mass of \(\mathrm{SnF}_2\)
Sum the products of each element's atomic mass and its subscript in the compound. For \(\mathrm{SnF}_2\):\[ M(\mathrm{SnF}_2) = 1 \times M(\mathrm{Sn}) + 2 \times M(\mathrm{F}) \]\[ = 1 \times 118.71 \text{ g/mol} + 2 \times 19.00 \text{ g/mol} \]\[ = 118.71 + 38.00 \]\[ = 156.71 \text{ g/mol} \]
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Atomic Mass
The atomic mass is the mass of a single atom of a chemical element. It's usually expressed in unified atomic mass units (u) or grams per mole (g/mol). In the periodic table, you can find the atomic mass listed under each element symbol. For instance, aluminum (Al) has an atomic mass of 26.98 g/mol, while fluorine (F) has an atomic mass of 19.00 g/mol.
The atomic mass is an essential concept in chemistry because it allows us to quantify the amount of matter. When calculating the molar mass of a compound, knowing the atomic masses of the comprising elements is the first step.
In our exercise, we gathered the atomic masses for the following elements:
The atomic mass is an essential concept in chemistry because it allows us to quantify the amount of matter. When calculating the molar mass of a compound, knowing the atomic masses of the comprising elements is the first step.
In our exercise, we gathered the atomic masses for the following elements:
- Aluminum (Al): 26.98 g/mol
- Fluorine (F): 19.00 g/mol
- Carbon (C): 12.01 g/mol
- Hydrogen (H): 1.01 g/mol
- Chlorine (Cl): 35.45 g/mol
- Tin (Sn): 118.71 g/mol
Compound Composition
Understanding a compound's composition means knowing how many atoms of each element are present in the molecule. Each element's amount is usually indicated by a subscript in the chemical formula.
Take the compound \(\mathrm{AlF}_3\) for example:
To find the compound's molar mass, we multiply the atomic mass of each element by the number of atoms present in the formula.
For \(\mathrm{AlF}_3\): \[ M(\mathrm{AlF}_3) = 1 \times 26.98 \text{ g/mol} + 3 \times 19.00 \text{ g/mol} = 83.98 \text{ g/mol} \]
Similarly, for \(\mathrm{C}_2 \mathrm{H}_4 \mathrm{Cl}_2\), breaking down the formula shows:
Take the compound \(\mathrm{AlF}_3\) for example:
- It contains one aluminum (Al) atom.
- It contains three fluorine (F) atoms.
To find the compound's molar mass, we multiply the atomic mass of each element by the number of atoms present in the formula.
For \(\mathrm{AlF}_3\): \[ M(\mathrm{AlF}_3) = 1 \times 26.98 \text{ g/mol} + 3 \times 19.00 \text{ g/mol} = 83.98 \text{ g/mol} \]
Similarly, for \(\mathrm{C}_2 \mathrm{H}_4 \mathrm{Cl}_2\), breaking down the formula shows:
- 2 carbon (C) atoms.
- 4 hydrogen (H) atoms.
- 2 chlorine (Cl) atoms.
Molecular Weight Determination
Molecular weight, also known as molar mass, is the sum of all the atomic masses in a molecule. It is critical in stoichiometry, which is the calculation of reactants and products in chemical reactions. To calculate the molar mass, follow these steps:
For example, to find the molecular weight of \(\mathrm{SnF}_2\):
First, we note it contains:
Then use the given atomic masses:
\[ M(\mathrm{SnF}_2) = 1 \times 118.71 \text{ g/mol} + 2 \times 19.00 \text{ g/mol} = 156.71 \text{ g/mol} \]
Understanding how to determine molecular weight is fundamental for solving chemistry problems related to stoichiometry and chemical composition.
- Identify the compound's chemical formula.
- Find the atomic masses of all elements in the compound (use the periodic table).
- Multiply the atomic mass of each element by its subscript in the chemical formula.
- Sum the results to get the compound's total molar mass.
For example, to find the molecular weight of \(\mathrm{SnF}_2\):
First, we note it contains:
- 1 tin (Sn) atom.
- 2 fluorine (F) atoms.
Then use the given atomic masses:
\[ M(\mathrm{SnF}_2) = 1 \times 118.71 \text{ g/mol} + 2 \times 19.00 \text{ g/mol} = 156.71 \text{ g/mol} \]
Understanding how to determine molecular weight is fundamental for solving chemistry problems related to stoichiometry and chemical composition.