Question

Nitrogen combines with oxygen to form nitrogen monoxide (no) and nitrogen dioxide (no2). a sample of no consists of 1.14 g of oxygen and 1 g of nitrogen. how many grams of oxygen combine with 1 g of nitrogen to form no2if the ratio of the masses of oxygen in these two compounds is exactly 1:2?

Answer 1

2N2 + 3O2 ---> 2NO + 2NO2  
You should do it based on moles and not grams. 
1.14 g O = 0.071 moles O 
1 g N = 0.071 moles N  
So in NO2 you need 2 moles O for each mole of N 
1 g N = 0.071 moles, so you need 0.071 x 2 moles of O = 0.0.142 moles O 
0.142 moles O x 16 g/mol = 2.27 grams of O. So, you are actually correct because your answer is 2.28 grams. I just prefer to work it out in moles so it makes perfect chemical sense.

Answer 2

Answer: The mass of oxygen that combines with nitrogen will be 2.272g.

Explanation:

To calculate the number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$   .....(1)

For Oxygen atom:

Given mass of oxygen atom = 1.14 g

Molar mass of oxygen atom = 16 g/mol

Putting values in above equation, we get:

$\text{Moles of oxygen atom}=\frac{1.14g}{16g/mol}=0.071mol$

For Nitrogen atom:

Given mass of nitrogen atom = 1 g

Molar mass of nitrogen atom = 14 g/mol

Putting values in above equation, we get:

$\text{Moles of nitrogen atom}=\frac{1g}{14g/mol}=0.071mol$

For the given chemical reaction:

$2N_2+3O_2\rightarrow 2NO+2NO_2$

In 1 mole of nitrogen dioxide molecule, 1 mole of nitrogen atom combines with 2 moles of oxygen atom.

So, 0.071 moles of nitrogen will combine with = $\frac{2}{1}\times 0.071=0.142moles$ of oxygen atom.

Now, to calculate the mass of oxygen atom, we use equation 1:

$0.142mol=\frac{\text{Mass of oxygen atom}}{16g/mol}\\\\\text{Mass of oxygen atom}=2.272g$

Hence, the mass of oxygen that combines with nitrogen will be 2.272g.