Which of the following questions does the provided solution answer: How many grams of Na are present in 30 g of NaOH? How many liters of H₂ can be produced by the decomposition of 3 moles of NH₃ at ST

• Step 1: Calculate the molar mass of NaOH. Molar mass of Na = $22.99 \text{ g/mol}$ Molar mass of O = $16.00 \text{ g/mol}$ Molar mass of H = $1.01 \text{ g/mol}$ Molar mass of NaOH = $22.99 + 16.00 + 1.01 = 40.00 \text{ g/mol}$
• Step 2: Determine the mass fraction of Na in NaOH. Mass fraction of Na = $\frac{\text{Molar mass of Na}}{\text{Molar mass of NaOH}} = \frac{22.99 \text{ g/mol}}{40.00 \text{ g/mol}} = 0.57475$
• Step 3: Calculate the mass of Na in 30 g of NaOH. Mass of Na = $30 \text{ g NaOH} \times 0.57475 = 17.2425 \text{ g}$ Rounding to the nearest gram, this is $17 \text{ g}$.

The correct answer is C. 17 g.

• Step 1: Write the balanced chemical equation for the decomposition of NH₃. $$2NH_3(g) \rightarrow N_2(g) + 3H_2(g)$$
• Step 2: Use stoichiometry to find the moles of H₂ produced from 3 moles of NH₃. From the equation, 2 moles of $NH_3$ produce 3 moles of $H_2$. Moles of $H_2 = 3 \text{ mol NH}_3 \times \frac{3 \text{ mol H}_2}{2 \text{ mol NH}_3} = 4.5 \text{ mol H}_2$
• Step 3: Convert moles of H₂ to liters at STP. At Standard Temperature and Pressure (STP), 1 mole of any ideal gas occupies $22.4 \text{ L}$. Volume of $H_2 = 4.5 \text{ mol} \times 22.4 \text{ L/mol} = 100.8 \text{ L}$ Rounding to the nearest liter, this is $101 \text{ L}$.

The correct answer is D. 101 L.

• Step 1: Identify the given values. Number of moles ($n$) = $3.50 \text{ mol}$ Volume ($V$) = $10.00 \text{ L}$ Temperature ($T$) = $300 \text{ K}$ Ideal gas constant ($R$) = $0.0821 \text{ L atm mol}^{-1} \text{ K}^{-1}$
• Step 2: Use the Ideal Gas Law ($PV = nRT$) to solve for pressure ($P$). $$P = \frac{nRT}{V}$$
• Step 3: Substitute the values and calculate $P$. $$P = \frac{(3.50 \text{ mol})(0.0821 \text{ L atm mol}^{-1} \text{ K}^{-1})(300 \text{ K})}{10.00 \text{ L}}$$ $$P = \frac{86.205}{10.00} \text{ atm}$$ $$P = 8.6205 \text{ atm}$$ Rounding to three significant figures, $P = 8.62 \text{ atm}$.

The correct answer is C. 8.62 atm.

Molarity is a measure of the concentration of a solute in a solution. It is defined as the number of moles of solute dissolved per liter of solution.

The correct answer is C. moles of solute per liter of solution.

• Step 1: Calculate the moles of the gas at STP. At STP, 1 mole of any ideal gas occupies $22.4 \text{ L}$. Moles of gas = $\frac{\text{Volume}}{\text{Molar volume at STP}} = \frac{11.2 \text{ L}}{22.4 \text{ L/mol}} = 0.5 \text{ mol}$
• **Step 2: Calculate the molar