For the reaction:

CH4(g) + 2O2(g)-->CO2(g)+2H2O (l)
ÄH = -50.38 kJ/mol,

How many moles of methane (CH4) must be burned to produce 137 kJ of heat?

For each mole of CH4 reacted there is 50.38 kj released.

137 kj * (1 mol/50.38 kj) = 2.719 moles of CH4. 4 sig figs

additional info: 50.38 is positive because it's asking how much heat is produced (released) and if you say -50.38 kj is released it's like a double negative.

i need help

To find the number of moles of methane (CH4) that must be burned to produce 137 kJ of heat, we need to use the concept of heat of reaction (ΔH).

The given reaction is:
CH4(g) + 2O2(g) --> CO2(g) + 2H2O(l)

The heat of reaction (ΔH) for this reaction is given as -50.38 kJ/mol, which means that for every 1 mole of methane burned, -50.38 kJ of heat is released.

To determine the number of moles, we can use the following equation:

ΔH = (q / n)

where:
ΔH = heat of reaction (-50.38 kJ/mol)
q = amount of heat released (137 kJ)
n = number of moles of CH4

Rearranging the equation to solve for n, we get:

n = (q / ΔH)

Plugging in the values, we have:

n = (137 kJ / -50.38 kJ/mol)

Calculating this, we find:

n ≈ -2.72 mol

Since the number of moles cannot be negative, we can discard the negative sign and conclude that approximately 2.72 moles of methane must be burned to produce 137 kJ of heat.