Question

Calculate the mass in grams of each of the following samples. a. 0.994 mole of benzene, \(\mathrm{C}_{6} \mathrm{H}_{6}\) b. 4.21 moles of calcium hydride c. \(1.79 \times 10^{-4}\) moles of hydrogen peroxide, \(\mathrm{H}_{2} \mathrm{O}_{2}\) d. 1.22 mmol of glucose, \(\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}\) ( \(1 \mathrm{mmol}=1 / 1000\) mole \()\) e. 10.6 moles of tin f. 0.000301 mole of strontium fluoride

Short answer

a. \(78.11 \: \text{g}\) b. \(168.63 \: \text{g}\) c. \(0.0061 \: \text{g}\) d. \(0.2204 \: \text{g}\) e. \(2247.1 \: \text{g}\) f. \(0.0436 \: \text{g}\)

Step-by-step solution

Find the atomic mass of each element

Use the periodic table to find the atomic mass of each element in the provided compounds. For this exercise you can refer to [Periodic table](https://www.tableau-periodique.fr/)

Find the molar mass of each compound

Multiply the atomic mass of each element by the number of atoms of that element in the compound and add these results together. a. Benzene, \(\mathrm{C}_{6}\mathrm{H}_{6}\): Molar mass \(= 6\:\mathrm{C} + 6\:\mathrm{H}\) b. Calcium hydride: Molar mass \(= 1\:\mathrm{Ca} + 2\:\mathrm{H}\) c. Hydrogen peroxide, \(\mathrm{H}_{2}\mathrm{O}_{2}\): Molar mass \(= 2\:\mathrm{H} + 2\:\mathrm{O}\) d. Glucose, \(\mathrm{C}_{6}\mathrm{H}_{12}\mathrm{O}_{6}\): Molar mass \(= 6\:\mathrm{C} + 12\:\mathrm{H} + 6\:\mathrm{O}\) e. Tin: Molar mass \(= 1\:\mathrm{Sn}\) f. Strontium fluoride: Molar mass \(= 1\:\mathrm{Sr} + 2\:\mathrm{F}\)

Calculate the mass in grams of each sample

Multiply the molar mass of each compound by the number of moles given. a. \(0.994\: \text{moles} \times M (\mathrm{C}_{6}\mathrm{H}_{6})\) b. \(4.21\: \text{moles} \times M (\text{calcium hydride})\) c. \(1.79 \times 10^{-4}\: \text{moles} \times M (\mathrm{H}_{2}\mathrm{O}_{2})\) d. \(1.22\: \text{mmol} \times M (\mathrm{C}_{6}\mathrm{H}_{12}\mathrm{O}_{6}) \times \frac{1}{1000}\) e. \(10.6\: \text{moles} \times M (\mathrm{Sn})\) f. \(0.000301\: \text{moles} \times M (\text{strontium fluoride})\) Calculate the mass in grams for each compound and provide the final results.

Key concepts

Atomic Mass

The atomic mass, often seen on the periodic table, is the mass of an atom expressed in atomic mass units (amu). Each element's atomic mass is essentially a weighted average of all the isotopes of that element. This time-saving number represents how heavy an atom is compared to carbon-12, which is set at 12 amu.
Understanding atomic mass is crucial in chemistry because it helps us calculate other important values, such as molar mass and the mass of substances in chemical reactions.

• Atomic mass is specific to each element.
• It is found on the periodic table.
• Helps in determining molar mass of compounds.

For instance, carbon (C) has an atomic mass of about 12 amu, and hydrogen (H) is about 1 amu. These values are used to calculate molar mass when dealing with compounds like benzene (C₆H₆), as illustrated in the exercise.

Molar Mass

Molar mass is the mass of one mole of a given substance and is expressed in grams per mole (g/mol). It combines the atomic masses of all the atoms in a molecule to give a total mass for one mole of that molecule. This is essential for converting between grams and moles in chemical calculations.

Here's how you can calculate molar mass: Take the atomic mass of each element from the periodic table, multiply it by the number of atoms of that element in the chemical formula, and sum these values.

For example, the calculation for benzene (C₆H₆) involves the following steps:

• Find the atomic mass for carbon (C) and hydrogen (H) from the periodic table.
• Multiply the atomic mass of C by 6, since there are six carbon atoms.
• Multiply the atomic mass of H by 6, for the six hydrogen atoms.
• Add both results together to find the molar mass of benzene.

This method is applicable to all chemical compounds, making molar mass a fundamental concept in chemistry calculations.

Periodic Table

The periodic table is a comprehensive chart that organizes all known chemical elements in an informative grid. This tool is indispensable in chemistry as it provides essential information about each element, including atomic mass, atomic number, and sometimes electron configuration.

Elements are arranged in order of increasing atomic number — this number indicates the number of protons in an atom. This organization helps chemists understand elemental properties, identify trends, and easily access atomic masses required for calculations.

Some features of the periodic table:

• Groups (vertical columns) indicate elements with similar chemical behaviors.
• Periods (horizontal rows) demonstrate changes in properties as you move across the table.
• Atomic mass found under each element's symbol assists in determining molar masses.

Using the periodic table effectively helps with tasks like the one in the exercise, as it allows for quick retrieval of atomic masses needed for mole to mass conversions.