How much heat is released when 6.00 g of methane is combusted using the reaction below? ch4 + 2o2 ? co2 + 2h2o ? hrxn = -890. kj

-333.75 KJ

Explanation:

From the reaction CH₄ + 2O₂ ⇒ CO₂ + 2H₂O    ΔHrxn = -890 KJ.

From the reaction, 1 mole of CH₄ combusts to give -890 KJ.

We now calculate the number of moles, n of CH₄ in 6.00g

n = mass of CH₄/molar mass of CH₄

molar mass of CH₄ = 12 g/mol + 4 × 1 g/mol = (12 + 4) g/mol = 16 g/mol

mass of CH₄ = 6.00 g

n = 6.00 g /16 g/mol = 0.375 mol

So we have 0.375 mol of CH₄ in 6.00g

From the reaction, 1 mole of CH₄ produces -890 KJ

then 0.375 mol produces 0.375 mol × -890 KJ/1 mol = -333.75 KJ

"record the time to complete a chemical reaction" would most likely be part of a lab procedure.