Question

Write the formula and calculate the molar mass for each of the following substances. a. barium chloride b. aluminum nitrate c. iron(II) chloride d. sulfur dioxide e. calcium acetate

Short answer

The chemical formulas and molar masses for the given substances are as follows: a. Barium Chloride (BaCl2): 208.23 g/mol b. Aluminum Nitrate (Al(NO3)3): 213.00 g/mol c. Iron(II) Chloride (FeCl2): 126.75 g/mol d. Sulfur Dioxide (SO2): 64.07 g/mol e. Calcium Acetate (Ca(CH3COO)2): 158.18 g/mol

Step-by-step solution

Substance a: Barium Chloride

1. Identify the elements and their oxidation states: Barium (Ba) has an oxidation state of +2, and Chlorine (Cl) has an oxidation state of -1. 2. Write the chemical formula: To balance the charges, we need two Chlorine atoms for each Barium atom. The chemical formula for Barium Chloride is BaCl2. 3. Calculate the molar mass: Ba: 137.33 g/mol Cl: 35.45 g/mol Molar mass of BaCl2 = (1 × 137.33) + (2 × 35.45) = 137.33 + 70.9 = 208.23 g/mol

Substance b: Aluminum Nitrate

1. Identify the elements and their oxidation states: Aluminum (Al) has an oxidation state of +3 and Nitrate (NO3) has an oxidation state of -1. 2. Write the chemical formula: To balance the charges, we need three Nitrate ions for each Aluminum ion. The chemical formula for Aluminum Nitrate is Al(NO3)3. 3. Calculate the molar mass: Al: 26.98 g/mol N: 14.01 g/mol O: 16.00 g/mol Molar mass of Al(NO3)3 = (1 × 26.98) + (3 × (1 × 14.01 + 3 × 16.00)) = 26.98 + 3 × (14.01 + 48) = 26.98 + 3 × 62.01 = 213.00 g/mol

Substance c: Iron(II) Chloride

1. Identify the elements and their oxidation states: Iron (Fe) has an oxidation state of +2, and Chlorine (Cl) has an oxidation state of -1. 2. Write the chemical formula: To balance the charges, we need two Chlorine atoms for each Iron atom. The chemical formula for Iron Chloride is FeCl2. 3. Calculate the molar mass: Fe: 55.85 g/mol Cl: 35.45 g/mol Molar mass of FeCl2 = (1 × 55.85) + (2 × 35.45) = 55.85 + 70.9 = 126.75 g/mol

Substance d: Sulfur Dioxide

1. Identify the elements: Sulfur (S) and Oxygen (O). 2. Write the chemical formula: The chemical formula for Sulfur Dioxide is SO2. 3. Calculate the molar mass: S: 32.07 g/mol O: 16.00 g/mol Molar mass of SO2 = (1 × 32.07) + (2 × 16.00) = 32.07 + 32 = 64.07 g/mol

Substance e: Calcium Acetate

1. Identify the elements and their oxidation states: Calcium (Ca) has an oxidation state of +2, and Acetate (CH3COO) has an oxidation state of -1. 2. Write the chemical formula: To balance the charges, we need two Acetate ions for each Calcium ion. The chemical formula for Calcium Acetate is Ca(CH3COO)2. 3. Calculate the molar mass: Ca: 40.08 g/mol C: 12.01 g/mol H: 1.01 g/mol O: 16.00 g/mol Molar mass of Ca(CH3COO)2 = (1 × 40.08) + (2 × (2 × 12.01 + 3 × 1.01 + 2 × 16.00)) = 40.08 + 2 × (24.02 + 3.03 + 32) = 40.08 + 2 × 59.05 = 158.18 g/mol

Key concepts

Chemical Formula

The chemical formula of a compound is like its recipe, detailing the elements involved and the number of atoms of each element in a single molecule of the compound. Understanding a chemical formula requires recognizing each element's symbol on the periodic table. For example, Barium Chloride (BaCl2) consists of one barium (Ba) atom and two chlorine (Cl) atoms. Similarly, the formula for Aluminum Nitrate, Al(NO3)3, shows one aluminum (Al) atom and three nitrate (NO3) ions. This notation is essential because it helps us identify how elements combine to form specific compounds, which is crucial for further calculations like molar mass.

Oxidation States

Oxidation states indicate the number of electrons an element can lose, gain, or share when forming chemical compounds. For instance, in Barium Chloride, barium has an oxidation state of +2 and chlorine -1; these oxidation states help balance the charges in the formula BaCl2.
Using oxidation states is critical, particularly in complex compounds. In Aluminum Nitrate (Al(NO3)3), aluminum has an oxidation state of +3 while the nitrate ion, (NO3), has a charge of -1. Balancing oxidation states ensures the overall neutrality of the compound and guides chemists in formulating correct chemical structures.

Elemental Mass

Elemental mass refers to the atomic mass of each element within a compound. It is measured in grams per mole (g/mol) and is found on the periodic table. This measurement is crucial when calculating the molar mass of a compound.
For instance, in calculating the molar mass of Iron(II) Chloride (FeCl2), we use the elemental masses: Fe = 55.85 g/mol and Cl = 35.45 g/mol. By multiplying these masses by their respective quantities in the formula, we find the molar mass. This systematic approach reveals the total weight of a mole of the compound, which is useful for chemical reactions and stoichiometric calculations.

Compound Balancing

Compound balancing ensures that the total charge of the compound is neutral. By balancing charges of ions using subscripts in formulas, we achieve compounds that do not have a net charge. This concept is evident in Calcium Acetate (Ca(CH3COO)2), where calcium, with a charge of +2, is balanced with two acetate ions each having a charge of -1.
Balancing compounds is fundamental in chemistry as it affects the compound's stability and reactivity. It requires careful calculation and understanding of each element's oxidation state. Ensuring compounds are balanced helps accurately represent their chemical composition, which is vital for further quantitative and qualitative analyses.