In a college biology experiment, 50 mg of methane and 60 mg of sulfate are mixed in a closed container. What is the limiting reagent, and how much excess reagent remains when that species has been exhausted

CH₄ is the excess reagent and SO₄²⁻ is the limiting reagent.

0.040 g

Explanation:

Step 1: Write the balanced reaction for the methane anaerobic oxidation

CH₄ + SO₄²⁻ ⇒ S²⁻ + CO₂ + 2 H₂O

Step 2: Establish the theoretical mass ratio between the reactants

According to the balanced equation, the theoretical mass ratio of CH₄ to SO₄²⁻ is 16.04:96.06 = 0.1670:1

Step 3: Establish the experimental mass ratio between the reactants

50 mg (0.050 g) of CH₄ react with 60 mg (0.060 g) of SO₄²⁻. The experimental mass ratio of CH₄ to SO₄²⁻ is 0.050:0.060 = 0.83:1

Comparing both mass ratios, we can deduce that CH₄ is the excess reagent and SO₄²⁻ is the limiting reagent.

Step 4: Calculate the mass excess of CH₄

The mass of CH₄ that reacts with 0.060 g of SO₄²⁻ is:

0.060 g SO₄²⁻ 16.04 g CH₄/96.06 g SO₄²⁻ = 0.010 g CH₄

The mass excess of CH₄ is:

0.050 g - 0.010 g = 0.040 g

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