What is the mass of water produced when 5 moles of hydrogen burn in the presence of excess oxygen?

2H2 + O2 ==> 2H2O

2 mols H2 will produce 2 mols H2O; therefore, 5 mols H2 will produce 5 mols H2O.
g H2O = mols H2O x molar mass H2O.

To determine the mass of water produced when hydrogen burns in the presence of excess oxygen, we need to know the balanced chemical equation for the reaction. The balanced equation for the combustion of hydrogen is:

2H₂ + O₂ → 2H₂O

From the balanced equation, we can see that 2 moles of hydrogen react with 1 mole of oxygen to produce 2 moles of water.

Given that 5 moles of hydrogen are burning, we need to determine how many moles of water will be produced. We can set up a conversion using the ratio of moles from the balanced equation:

5 moles H₂ * (2 moles H₂O / 2 moles H₂) = 5 moles H₂O

Therefore, 5 moles of hydrogen will produce 5 moles of water.

To calculate the mass of the water produced, we need to know the molar mass of water (H₂O). The molar mass of water is the sum of the molar masses of its constituent elements:

H = 1 gram/mole
O = 16 grams/mole

Molar mass of H₂O = 2(1 gram/mole) + 16 grams/mole = 18 grams/mole

To find the mass of water produced, we multiply the number of moles by the molar mass:

5 moles H₂O * 18 grams/mole = 90 grams of water

Therefore, when 5 moles of hydrogen burn in the presence of excess oxygen, it will produce 90 grams of water.