Molar Calculations with Reactions Quiz + Explanations

Step 1: Write the unbalanced equation:

\(\text{CH}_4 + \text{O}_2 \rightarrow \text{CO}_2 + \text{H}_2\text{O}\)

Step 2: Balance the hydrogens first:

\(\text{CH}_4 + \text{O}_2 \rightarrow \text{CO}_2 + 2\text{H}_2\text{O}\)

Step 3: Balance the oxygens:

\(\text{CH}_4 + 2\text{O}_2 \rightarrow \text{CO}_2 + 2\text{H}_2\text{O}\)

Step 4: The molar ratio of methane to oxygen is 1:2.

Step 1: Write the unbalanced equation:

\(\text{Na} + \text{P}_4 \rightarrow \text{Na}_3\text{P}\)

Step 2: Balance the sodium atoms:

\(12\text{Na} + \text{P}_4 \rightarrow 4\text{Na}_3\text{P}\)

Step 3: The molar ratio of sodium to phosphorus is 12:1.

Step 1: Write the balanced chemical equation:

\(\text{Ca(OH)}_2 + \text{CO}_2 \rightarrow \text{CaCO}_3 + \text{H}_2\text{O}\)

Step 2: Observe the coefficients in the balanced equation:

The molar ratio of calcium hydroxide to calcium carbonate is 1:1.

Step 1: Write the balanced equation:

\(2\text{Na} + 2\text{H}_2\text{O} \rightarrow 2\text{NaOH} + \text{H}_2\)

Step 2: Determine the molar ratio of sodium to hydrogen gas:

The ratio is 2:1.

Step 3: Calculate moles of sodium required:

\(\text{Moles of Na} = 0.54 \times 2 = 1.08\,\text{mol}\)

Step 4: Convert moles of sodium to grams:

\(\text{Mass of Na} = 1.08 \times 23 = 24.84\,\text{g}\)

Step 1: Write the unbalanced equation:

\(\text{S} + \text{O}_2 \rightarrow \text{SO}_2\)

Step 2: Balance the sulfur and oxygen atoms:

The equation is already balanced as written:

\(\text{S} + \text{O}_2 \rightarrow \text{SO}_2\)

Step 1: Write the balanced equation:

\(\text{S} + \text{BaO} \rightarrow \text{BaS} + \text{O}_2\)

Step 2: Observe the coefficients in the balanced equation:

The molar ratio of sulfur to barium sulfide is 1:1.

Step 1: Write the balanced equation:

\(\text{CH}_4 + 2\text{O}_2 \rightarrow \text{CO}_2 + 2\text{H}_2\text{O}\)

Step 2: Identify the molar ratio of methane to water:

\(1:2\)

Step 3: Use the ratio to calculate moles of water:

\(\text{Moles of water} = \text{Moles of methane} \times 2 = 2 \times 2 = 4\)

Final Answer: 4 moles of water are produced.

Step 1: Write the balanced equation:

\(12\text{Na} + \text{P}_4 \rightarrow 4\text{Na}_3\text{P}\)

Step 2: Determine the molar ratio of sodium to sodium phosphide:

\(12:4 = 3:1\)

Step 3: Use the ratio to calculate moles of sodium phosphide:

\(\text{Moles of Na}_3\text{P} = \frac{0.5}{3} = 0.167\,\text{mol}\)

Final Answer: 0.167 moles of sodium phosphide are produced.

Step 1: Write the balanced equation:

\(\text{Ca(OH)}_2 + \text{CO}_2 \rightarrow \text{CaCO}_3 + \text{H}_2\text{O}\)

Step 2: Determine the molar ratio:

\(1:1\)

Step 3: Calculate the mass of calcium carbonate:

\(\text{Mass} = \text{Moles} \times \text{Molar Mass} = 0.500 \times 100.1 = 50.05\,\text{g}\)

Final Answer: 50.05 g of calcium carbonate are produced.

Step 1: Write the balanced equation:

\(2\text{Na} + 2\text{H}_2\text{O} \rightarrow 2\text{NaOH} + \text{H}_2\)

Step 2: Identify the products:

Sodium hydroxide (\(\text{NaOH}\)) and hydrogen gas (\(\text{H}_2\)).

Step 1: Write the balanced equation:

\(\text{S} + \text{O}_2 \rightarrow \text{SO}_2\)

Step 2: Determine the molar ratio:

\(1:1\)

Step 3: Calculate the mass of sulfur:

\(\text{Mass} = \text{Moles} \times \text{Molar Mass} = 0.250 \times 32.07 = 8.02\,\text{g}\)

Final Answer: 8.02 g of sulfur are required.

Step 1: Write the balanced equation:

\(\text{BaO} + \text{S} \rightarrow \text{BaS}\)

Step 2: Determine the molar ratio:

\(1:1\)

Step 3: Use the ratio to calculate moles of barium sulfide:

\(\text{Moles of BaS} = \text{Moles of BaO} = 2.00\)

Final Answer: 2.00 moles of barium sulfide are produced.