Question

Determine the number of moles present in each compound. a. 22.6 \(\mathrm{g} \mathrm{AgNO}_{3}\) b. 6.50 \(\mathrm{g} \mathrm{ZnSO}_{4}\) c. 35.0 \(\mathrm{g} \mathrm{HCl}\)

Short answer

The number of moles present in each compound are as follows: a. 0.133 mol of AgNO3 b. 0.040 mol of ZnSO4 c. 0.960 mol of HCl

Step-by-step solution

Determine the molar mass of AgNO3

To determine the molar mass of AgNO3, we need to add the molar masses of its constituent elements: silver (Ag), nitrogen (N), and oxygen (O). Molar mass of AgNO3 = (Molar mass of Ag) + (Molar mass of N) + (3 * Molar mass of O) Using the periodic table, we find the molar masses: Ag = 107.87 g/mol N = 14.01 g/mol O = 16.00 g/mol Molar mass of AgNO3 = 107.87 + 14.01 + (3 * 16.00) = 169.88 g/mol

Divide mass of AgNO3 by molar mass

Now, we'll divide the given mass of 22.6 g of AgNO3 by its molar mass of 169.88 g/mol: Number of moles of AgNO3 = (22.6 g) / (169.88 g/mol)

Calculate the number of moles

Finally, we calculate the number of moles: Number of moles of AgNO3 = 0.133 mol b. 6.50 g ZnSO4

Determine the molar mass of ZnSO4

To determine the molar mass of ZnSO4, we need to add the molar masses of its constituent elements: zinc (Zn), sulfur (S), and oxygen (O). Molar mass of ZnSO4 = (Molar mass of Zn) + (Molar mass of S) + (4 * Molar mass of O) Using the periodic table, we find the molar masses: Zn = 65.38 g/mol S = 32.07 g/mol O = 16.00 g/mol Molar mass of ZnSO4 = 65.38 + 32.07 + (4 * 16.00) = 161.45 g/mol

Divide mass of ZnSO4 by molar mass

Now, we'll divide the given mass of 6.50 g of ZnSO4 by its molar mass of 161.45 g/mol: Number of moles of ZnSO4 = (6.50 g) / (161.45 g/mol)

Calculate the number of moles

Finally, we calculate the number of moles: Number of moles of ZnSO4 = 0.040 mol c. 35.0 g HCl

Determine the molar mass of HCl

To determine the molar mass of HCl, we need to add the molar masses of its constituent elements: hydrogen (H) and chlorine (Cl). Molar mass of HCl = (Molar mass of H) + (Molar mass of Cl) Using the periodic table, we find the molar masses: H = 1.01 g/mol Cl = 35.45 g/mol Molar mass of HCl = 1.01 + 35.45 = 36.46 g/mol

Divide mass of HCl by molar mass

Now, we'll divide the given mass of 35.0 g of HCl by its molar mass of 36.46 g/mol: Number of moles of HCl = (35.0 g) / (36.46 g/mol)

Calculate the number of moles

Finally, we calculate the number of moles: Number of moles of HCl = 0.960 mol

Key concepts

Molar Mass Calculation

Molar mass is the weight of a substance's elements combined to produce a given compound. When you calculate molar mass, you take the atomic masses of all the atoms present in the compound and add them together. This gives the mass of one mole of that compound in grams. The unit for molar mass is grams per mole (g/mol). For example, to find the molar mass of silver nitrate, AgNO3, you would:

• Find the mass of each element in the compound: silver (Ag) is 107.87 g/mol, nitrogen (N) is 14.01 g/mol, and oxygen (O) is 16.00 g/mol.
• Add these together, considering there are three oxygen atoms: 107.87 + 14.01 + (3 * 16.00) = 169.88 g/mol.

Understand that this calculation steps up the stage for determining the number of moles from a given mass of a compound.

Chemical Formula Interpretation

Interpreting chemical formulas is essential for understanding what elements constitute a compound and how to determine their amounts. A chemical formula like ZnSO4 tells us directly:

• There is one atom of zinc (Zn).
• There is one atom of sulfur (S).
• There are four atoms of oxygen (O).

From this interpretation, it's crucial to realize the chemical formula gives the ratios of the elements in a particular compound. For instance, in the case of ZnSO4, it suggests the compound consists of one zinc atom made stable by sulfate (SO4), which contains a specific blend of sulfur and oxygen atoms. Understanding this helps you calculate the molar mass and perform a variety of chemical calculations effectively.

Periodic Table Usage

The periodic table is an essential tool in chemistry for obtaining information about various elements. Each element’s position tells us about its atomic number, group, period, and atomic mass, which is vital for calculating molar masses.

• Atomic Mass: Located beneath the element symbol, atomic mass is crucial for determining how much one mole of an element weighs. For example, hydrogen (H) has an atomic mass of 1.01 g/mol.
• Groups and Periods: Elements are organized into columns called groups and rows called periods, which help in predicting element properties and their chemical behavior.

By effectively using the periodic table, you can easily find the molar mass of the elements in compounds like HCl. The key is to utilize the atomic masses provided to sum up the mass of all constituent atoms within the compound, thus enabling accurate molar mass calculations.