I've run into some difficulty with my chemistry homework. We went over this practise question in class today as an example. However, I wasn't able to fully grasp how to work it out.
"How many grams of nitrogen form when 34.6 grams of nitrogen dioxide decomposes according to this
chemical equation:2 NO2 --> N2 + 2 O2?"
Kara,
the conceptual plan would be to go from grams of No2 to grams of N2 by first using the molar mass to convert grams to moles of NO2. Now use the mole ratio of NO2 to N2, then use the Molar mass of N2 to get grams of N2
Work from mole:mole ratios. That is, convert given grams of NO to moles and apply to equation.
Let x = moles of N2 produced and set up a linear ratio;i.e,
From the equation, 2NO => N2 + 2O2 => (2 mole NO/1.153 mole NO) = (1 mole N2/x) Solve for 'x'= (1/2)(1.153 mole N2) = 0.577 mole N2 Theoretical Yield. If you need gram yield, multiply mole Yield of N2 by formula wt of N2 (=28g/mole). That is, gms N2 = (0.577 mole N2)(28g/mole) = 16.14gms N2.
Let y = moles of O2 produced and set up linear ratio as before...
=> (2 mole NO2/ 1.153 mole NO2) = (2 mole O2/y) and solve for y = 1.153 mole O2 Theoretical Yield. For grams O2, multiply Theoretical Yield by 32g/mole. That is, gms O2 = (1.153 mole O2)(32 gms/mole) = 36.896 gms O2. Note, since coefficients in the equation for NO and O2 are the same, you can assume that 1.153 mole of O2 will be obtained from 1.153 mole of NO. N2 is half of equation moles NO.
To solve this problem, you need to use the concept of stoichiometry, which involves balancing chemical equations and determining the relationship between reactants and products.
1. Start by balancing the equation:
2 NO2 --> N2 + 2 O2.
The balanced equation tells us that two moles of nitrogen dioxide (NO2) will produce one mole of nitrogen gas (N2).
2. Convert the given mass of nitrogen dioxide (NO2) into moles. To do this, you need to know the molar mass of nitrogen dioxide, which is 46.01 g/mol.
34.6 g NO2 x (1 mol NO2 / 46.01 g NO2) = 0.752 mol NO2.
3. Now, use the stoichiometric ratio from the balanced equation to determine how many moles of nitrogen (N2) will form. From the balanced equation, we know that for every 2 moles of NO2, we will get one mole of N2.
0.752 mol NO2 x (1 mol N2 / 2 mol NO2) = 0.376 mol N2.
4. Finally, convert moles of nitrogen (N2) to grams by using the molar mass of nitrogen, which is 28.01 g/mol.
0.376 mol N2 x (28.01 g N2 / 1 mol N2) = 10.53 g N2.
Therefore, 34.6 grams of nitrogen dioxide will decompose to form 10.53 grams of nitrogen gas.