Sure! Let's go through each question step by step. --- ## 3. How many oxygen atoms are present in 6. moles of sodium sulfate? **Step 1: Find the chemical formula for sodium sulfate.** Sodium sulfate = **Na₂SO₄** **Step 2: Count the number of oxygen atoms per molecule.** Each molecule of Na₂SO₄ has **4 oxygen atoms**. **Step 3: Find the total number of molecules in 6. moles.** 1 mole = \(6.022 \times 10^{23}\) molecules (Avogadro's number) So, 6. moles = \(6. \times 6.022 \times 10^{23}\) molecules = \(3.613 \times 10^{24}\) molecules **Step 4: Find the total number of oxygen atoms:** Each molecule has 4 oxygen atoms, so: \(3.613 \times 10^{24} \text{ molecules} \times 4 = 1.445 \times 10^{25} \text{ oxygen atoms}\) --- ## 4. A 72.-gram sample of ethanol contains how many molecules? **Step 1: Find the chemical formula and molar mass of ethanol.** Ethanol = **C₂H₅OH** Molar mass = \(2 \times 12.01 + 6 \times 1.01 + 1 \times 16.00 = 46.08 \text{ g/mol}\) **Step 2: Convert grams to moles:** \[ \text{Moles} = \frac{72. \text{ g}}{46.08 \text{ g/mol}} = 1.563 \text{ moles} \] **Step 3: Convert moles to molecules:** \[ 1.563 \text{ moles} \times 6.022 \times 10^{23} = 9.41 \times 10^{23} \text{ molecules} \] --- ## 5. How many atoms of sodium are present in 3.5 grams of sodium sulfate? **Step 1: Find the molar mass of sodium sulfate (Na₂SO₄):** \[ 2 \times 22.99 + 32.07 + 4 \times 16.00 = 142.05 \text{ g/mol} \] **Step 2: Convert grams to moles:** \[ \text{Moles} = \frac{3.5 \text{ g}}{142.05 \text{ g/mol}} = .0246 \text{ moles} \] **Step 3: Find moles of sodium atoms:** Each formula unit has 2 sodium atoms. So, moles of sodium atoms = \(.0246 \times 2 = .0492\) moles **Step 4: Convert moles of sodium atoms to atoms:** \[ .0492 \text{ moles} \times 6.022 \times 10^{23} = 2.96 \times 10^{22} \text{ sodium atoms} \] --- ### **Summary Table** | Question | Calculation | Answer | |----------|-------------|--------| | 3 | \(6.\) moles × \(6.022 \times 10^{23}\) × 4 | \(1.45 \times 10^{25}\) oxygen atoms | | 4 | \(72.\) g ÷ \(46.08\) g/mol × \(6.022 \times 10^{23}\) | \(9.41 \times 10^{23}\) molecules | | 5 | \(3.5\) g ÷ \(142.05\) g/mol × 2 × \(6.022 \times 10^{23}\) | \(2.96 \times 10^{22}\) sodium atoms | If you need more details or have questions about the steps, let me know!

Certainly! Let's break down each section of the image you provided, focusing on the key concepts in chemistry. --- ## 1. Understanding Moles **Definition of a Mole** A mole is a unit of measurement in chemistry that represents \(6.022 \times 10^{23}\) particles (atoms, molecules, etc.). This number is known as Avogadro's number. --- ## 2. Chemical Formulas ### Example: Sodium Sulfate (Na₂SO₄) - **Composition**: - 2 Sodium (Na) atoms - 1 Sulfur (S) atom - 4 Oxygen (O) atoms - **Total**: Each molecule of sodium sulfate has 7 atoms in total. --- ## 3. Calculating Atoms in a Compound ### Example: Oxygen Atoms in Sodium Sulfate - **Step 1: Identify the number of oxygen atoms** in one molecule of sodium sulfate: **4**. - **Step 2: Determine the number of molecules** in a given number of moles using Avogadro's number. ### Calculation For \(n\) moles of Na₂SO₄: \[ \text{Total oxygen atoms} = n \times 6.022 \times 10^{23} \times 4 \] --- ## 4. Molar Mass Calculations ### Example: Ethanol (C₂H₅OH) - **Step 1: Calculate the molar mass**: - Carbon (C): \(12.01 \, \text{g/mol} \times 2 = 24.02 \, \text{g/mol}\) - Hydrogen (H): \(1.01 \, \text{g/mol} \times 6 = 6.06 \, \text{g/mol}\) - Oxygen (O): \(16.00 \, \text{g/mol} \times 1 = 16.00 \, \text{g/mol}\) - **Total Molar Mass**: \(46.08 \, \text{g/mol}\) ### Step 2: Converting Grams to Moles Using the formula: \[ \text{Moles} = \frac{\text{mass (g)}}{\text{molar mass (g/mol)}} \] ### Step 3: Converting Moles to Molecules Using Avogadro's number: \[ \text{Molecules} = \text{moles} \times 6.022 \times 10^{23} \] --- ## 5. Summary of Calculations To summarize, always remember: - Use the chemical formula to determine the number of each type of atom. - Convert grams to moles using molar mass. - Use Avogadro's number to convert moles to actual particles. If you have specific parts of the image you would like to clarify further, feel free to ask!