you start with 150.0g of pentane and 500.0L of O2. how many grams of H2O will you make?

To determine the number of grams of H2O produced, we need to first calculate the balanced chemical equation for the reaction between pentane (C5H12) and oxygen (O2) to form water (H2O) and carbon dioxide (CO2).

The balanced equation is as follows:

C5H12 + 8O2 → 5CO2 + 6H2O

We can see from the equation that for every 1 mole of pentane, we produce 6 moles of water. Therefore, we need to convert the given mass of pentane to moles and then use the molar ratio to calculate the moles of water produced. Finally, we can convert the moles of water back to grams.

First, let's calculate the moles of pentane:

Molar mass of pentane (C5H12) = 5 * atomic mass of carbon (C) + 12 * atomic mass of hydrogen (H)
= 5 * 12.01 g/mol + 12 * 1.01 g/mol
= 72.14 g/mol

moles of pentane = mass of pentane / molar mass of pentane
= 150.0 g / 72.14 g/mol
≈ 2.079 mol

Now, using the molar ratio from the balanced equation, we can calculate the moles of water produced:

moles of water = 6 * moles of pentane
= 6 * 2.079 mol
≈ 12.474 mol

Finally, we can convert the moles of water to grams:

mass of water = moles of water * molar mass of water
= 12.474 mol * (2 * atomic mass of hydrogen + atomic mass of oxygen)
= 12.474 mol * (2 * 1.01 g/mol + 16.00 g/mol)
≈ 324.3 g

Therefore, approximately 324.3 grams of water will be produced when starting with 150.0 grams of pentane and 500.0 liters of oxygen.

This is a limiting reagent problem. I know that because amounts for BOTH reactants are given.

C5H12 + 8O2 ==> 5CO2 + 6H2O
mols C5H12 = grams/molar mass
mols O2 = L O2/22.4 = ?

Convert mols C5H12 to mols H2O using the coefficients in the balanced equation..
Convert mols O2 to mols H2O.
It is likely these two numbers will not be the same which means one of them is wrong. The correct value in limiting reagent problems is ALWAYS the smaller value and the reagent producing that value is the limiting regent.
Now convert the smaller value mols H2O to grams. g = mols x molar mass.