Final answer:
To determine the number of molecules of methane gas at STP, we can use the volume and molar volume at STP. By dividing the given volume by the molar volume and then multiplying the result by Avogadro's number, we can find the number of molecules. Therefore we get 1.490 x 1029 molecules.
Step-by-step explanation:
To determine the number of molecules in 5.56 x 106 L of methane at STP, we can use Avogadro's number, which is approximately 6.022 x 1023 molecules/mol. First, we need to calculate the number of moles of methane. We can use the volume and the molar volume at STP, which is 22.4 L/mol. Divide the given volume by the molar volume:
5.56 x 106 L / 22.4 L/mol = 2.475 x 105 mol
Next, multiply the number of moles by Avogadro's number to find the number of molecules:
2.475 x 105 mol x 6.022 x 1023 molecules/mol = 1.490 x 1029 molecules