A TECHNICION PLAES 0.50 MOL OF NITROGEN MONOXIDE GAS AND 0.20 MOL IF CHLORINE GAS IN A 1.00L SEALED CONTAINER AT 100 DEGREES CELSUIS. THE FOLLOWING EQUALIBRIUM IS ESTABLISHED AT 4.5 MIN.
2NO(g) + Cl2(g) --->2NOCK(g)
the arrow is supposed to be meant as forward and reverse
THE TECHNICION DETERMIBES THAT AT EQUALIBRIUM THERE ARE 0.30 MOL OF NOCL, 0.20 mol of nitrogen monoxide and 0.050 mol of chlorine gas.
question 1
calculate the percent yeild
question 2
calculate the equalibrium constant
6 years ago
Answered By Leonardo F
In order to calculate the percent yield, we have to know how much of each reactant has reacted by subtracting the equilibrium amount from the initial amount of moles of each one. We can construct the following:
$2NO_{\left(g\right)}+Cl_{2_{\left(g\right)}}\leftrightarrow2NOCl_{\left(g\right)}$2NO(g)+Cl2(g)↔2NOCl(g)
$NO_{\left(g\right)}$NO(g) (initial amount: 0.50 mol; equilibrium amount: 0.20 mol; amount reacted: 0.50 - 0.20 = 0.30 mol)
$Cl_{2_{\left(g\right)}}$Cl2(g) (initial amount: 0.20 mol; equilibrium amount: 0.05 mol; amount reacted: 0.20 - 0.05 = 0.15 mol)
$NOCl_{\left(g\right)}$NOCl(g) (initial amount: 0 mol; equilibrium amount: 0.30 mol; amount formed: 0 + 0.30 = 0.30 mol)
Now, we must find out what is the limiting reagent in the reaction. We know that the molar proportion of nitrogen monoxide to chlorine gas is 2:1 (this means that 2 moles of NO is required for each mole of chlorine). Since we have initially 0.50 mol of NO, according to the proportion, we would need initially 0.25 mol of chlorine gas, but we only have 0.20 mol of it. This means that the chlorine gas is the limiting reagent, while the nitrogen monoxide is in excess.
Since we now know the limiting reagent, the percent yield is the division of the actual yield by the theoretical yield. The actual yield is 0.3 mol, because 0.3 mol of NOCl was actually formed in the reaction process. If we have initially 0.2 mol of chlorine gas and all of it had reacted, we would have formed 0.4 mol of NOCl. This is the theoretical yield. Hence:
$Yield=\frac{0.3mol}{0.4mol}=0.75=75\%$Yield=0.3mol0.4mol =0.75=75%
The equilibrium constant (Kc) is obtained by dividing the concentrations of the products by the concentrations of the reactants (each powered by its own stoichiometric coefficient). For this particular case, we know that the total volume is 1.00 L. So, if we divide the amount of moles in the equilibrium by 1 L, we get the concentration of the chemical compounds in the reaction in mol/L:
$Kc=\frac{\left[NOCl\right]^2}{\left[NO\right]^2\left[Cl_2\right]}=\frac{\left(0.30\right)^2}{\left(0.20\right)^2\left(0.05\right)}=45$Kc=[NOCl]2[NO]2[Cl2] =(0.30)2(0.20)2(0.05) =45
The value of the equilibrium constant is 45.