Question

Calculate the molar mass for each of the following substances. a. ferrous sulfate b. mercuric iodide c. stannic oxide d. cobaltous chloride e. cupric nitrate

Short answer

The molar masses of the given compounds are as follows: a. Ferrous sulfate (FeSO4): 151.87 g/mol b. Mercuric iodide (HgI2): 454.39 g/mol c. Stannic oxide (SnO2): 150.71 g/mol d. Cobaltous chloride (CoCl2): 129.83 g/mol e. Cupric nitrate (Cu(NO3)2): 187.57 g/mol

Step-by-step solution

a. Calculate the molar mass of ferrous sulfate (FeSO4)

1. Identify the atomic mass of each element in the compound: - Iron (Fe): 55.85 g/mol - Sulfur (S): 32.07 g/mol - Oxygen (O): 16.00 g/mol 2. Multiply the atomic mass of each element by the number of atoms in the compound and sum the values: - Fe: 1 × 55.85 g/mol - S: 1 × 32.07 g/mol - O: 4 × 16.00 g/mol 3. Add the mass contribution of each element: Molar mass of FeSO4 = 55.85 + 32.07 + (4 × 16) = 151.87 g/mol

b. Calculate the molar mass of mercuric iodide (HgI2)

1. Identify the atomic mass of each element in the compound: - Mercury (Hg): 200.59 g/mol - Iodine (I): 126.90 g/mol 2. Multiply the atomic mass of each element by the number of atoms in the compound and sum the values: - Hg: 1 × 200.59 g/mol - I: 2 × 126.90 g/mol 3. Add the mass contribution of each element: Molar mass of HgI2 = 200.59 + (2 × 126.90) = 454.39 g/mol

c. Calculate the molar mass of stannic oxide (SnO2)

1. Identify the atomic mass of each element in the compound: - Tin (Sn): 118.71 g/mol - Oxygen (O): 16.00 g/mol 2. Multiply the atomic mass of each element by the number of atoms in the compound and sum the values: - Sn: 1 × 118.71 g/mol - O: 2 × 16.00 g/mol 3. Add the mass contribution of each element: Molar mass of SnO2 = 118.71 + (2 × 16) = 150.71 g/mol

d. Calculate the molar mass of cobaltous chloride (CoCl2)

1. Identify the atomic mass of each element in the compound: - Cobalt (Co): 58.93 g/mol - Chlorine (Cl): 35.45 g/mol 2. Multiply the atomic mass of each element by the number of atoms in the compound and sum the values: - Co: 1 × 58.93 g/mol - Cl: 2 × 35.45 g/mol 3. Add the mass contribution of each element: Molar mass of CoCl2 = 58.93 + (2 × 35.45) = 129.83 g/mol

e. Calculate the molar mass of cupric nitrate (Cu(NO3)2)

1. Identify the atomic mass of each element in the compound: - Copper (Cu): 63.55 g/mol - Nitrogen (N): 14.01 g/mol - Oxygen (O): 16.00 g/mol 2. Multiply the atomic mass of each element by the number of atoms in the compound and sum the values: - Cu: 1 × 63.55 g/mol - N: 2 × 14.01 g/mol - O: 6 × 16.00 g/mol 3. Add the mass contribution of each element: Molar mass of Cu(NO3)2 = 63.55 + (2 × 14.01) + (6 × 16) = 187.57 g/mol

Key concepts

Atomic Mass

Understanding atomic mass is fundamental when calculating the molar mass of chemical compounds. Atomic mass refers to the mass of a single atom of a chemical element. It's usually expressed in atomic mass units (amu). The atomic mass is primarily determined by the number of protons and neutrons in an atom's nucleus. For example, the atomic mass of iron (Fe) is 55.85 amu, which means a single iron atom weighs approximately 55.85 amu.
However, when we talk about atomic mass in the context of chemistry, we're often referring to its average atomic mass as found on the periodic table. This average takes into account the different isotopes of an element and their abundance in nature.

• The average atomic mass is crucial for practical calculations, like determining the molar mass of compounds.
• Molar mass is calculated by multiplying the atomic mass of each element by its quantity in the compound, and then summing these values.

This understanding aids in tasks such as determining the amounts of substances used in chemical reactions.

Chemical Compounds

Chemical compounds are substances composed of two or more different types of atoms bonded together. They are characterized by their fixed ratios of elements. This consistency in composition makes it possible for chemists to predict and calculate various properties of compounds.
Each compound is represented by a unique chemical formula, which provides information about which elements are present and in what quantities. For instance, ferrous sulfate is represented as \(\text{FeSO}_4\), indicating one iron atom, one sulfur atom, and four oxygen atoms in each molecule.

• Understanding chemical compounds allows you to calculate molar mass, which is pivotal in stoichiometric calculations.
• By knowing the precise formula of a compound, you can determine the total weight contribution of each constituent element.

This knowledge of formulas and their interpretations is essential in fields such as pharmacology, materials science, and environmental science.

Stoichiometry

Stoichiometry is the area of chemistry that deals with the quantitative relationships, or ratios, between reactants and products in a chemical reaction. This involves calculations based on balanced chemical equations, which use the principles of the conservation of mass.
Understanding how to calculate the molar masses of chemical compounds allows you to apply stoichiometry effectively. Once the molar mass of each substance is known, you can convert between moles and grams, facilitating the prediction of the amounts needed or produced in a reaction.

• Stoichiometry enables chemists to design processes that maximize yields and minimize costs.
• It is invaluable in laboratories and industry for preparing solutions, scaling reactions, and analyzing experimental data.

By mastering stoichiometry, one gains the ability to approach real-world problems with a systematic method, ensuring efficient and precise results in chemical processes.