for the reaction: 4NH3+5O2=4NO+6H2O; 15.0g of NH3 and 27.5g of O2 were reacted.

a). which is the limiting reactant?
b).how many moles of NO are formed from the limiting reactant in the above reaction.
what would be the first step in this problem?

How much of this do you know how to do? Be specific. I can help you through it but I'm not inclined to work it in detail if you already know how to do some of it.

i know how to do the moles but i couldn't figure out which one is the limiting reactant. to do the moles first i figured out the molecular weight for NO(30.01). but i don't understand what the mass in grams will be.

The first step in solving this problem is to determine the moles of each reactant involved in the reaction.

a) To find out which reactant is the limiting reactant, we need to compare the moles of NH3 and O2.

1. Calculate the number of moles of NH3:
Moles of NH3 = (mass of NH3) / (molar mass of NH3)

Given: mass of NH3 = 15.0g
The molar mass of NH3 can be found by summing the atomic masses of nitrogen (N) and hydrogen (H) in NH3:
Molar mass of NH3 = (atomic mass of N) + 3 × (atomic mass of H)

2. Calculate the number of moles of O2:
Moles of O2 = (mass of O2) / (molar mass of O2)

Given: mass of O2 = 27.5g
The molar mass of O2 can be found by multiplying the atomic mass of oxygen (O) by 2:
Molar mass of O2 = 2 × (atomic mass of O)

After calculating the moles of NH3 and O2, compare the ratios between the coefficients of both reactants in the balanced equation. The reactant with the smaller ratio is the limiting reactant.

b) Once you determine the limiting reactant, you can use its mole ratio with the product, NO, to calculate the moles of NO produced. According to the balanced equation, the mole ratio between NH3 and NO is 4:4, meaning 4 moles of NH3 produce 4 moles of NO. Similarly, the mole ratio between O2 and NO is 5:4.

To calculate the moles of NO formed from the limiting reactant in the above reaction, multiply the moles of the limiting reactant by the mole ratio between the limiting reactant and NO.

I hope this helps! Let me know if you have any further questions.