#K_b# for #"acetoaminophen"# is #4.1xx10^-4#. What is #[HO^-]# for a solution of #"acetoaminophen"# at #0.910*mol*L^-1# concentration?

Answer 1

#[HO^-]=0.019*mol*L^-1#

#C_8H_9N_3O_2NH + H_2O rightleftharpoonsC_8H_9N_3O_2NH^(+) + HO^-#

The expression for base association is written in the standard manner:

#K_b=([C_8H_9N_3O_2NH^+][HO^-])/([C_8H_9N_3O_2NH])=4.1xx10^-4#
If, #[HO^-]=x#, then clearly (because of the size of #K_b#), #[C_8H_9N_3O_2NH]" >> "[HO^-]#, i.e. #[C_8H_9N_3O_2NH]" >> "x#. Given that #[HO^-]=x#, #x=[C_8H_9N_3O_2NH^+]#, and #[C_8H_9N_3O_2N]=(0.910-x)#
i.e., so if #K_b=(x^2)/(0.910-x)#
#K_b~=(x^2)/(0.910)#, this is an approximation, which we must justify later.
#x_1=sqrt(K_bxx0.910)=sqrt(4.1xx10^-4xx0.910)=0.019#
Since we got an approximation for #x#, we can recycle this value thru the equilibrium expression, and see if our estimate of #x_2# varies markedly:

#x_2=sqrt(K_bxx (0.910-0.019))=sqrt(4.1xx10^-4xx(0.910-0.019))=0.019molL^-1#

Our approximation was indeed reasonable. And thus #x=[HO^-]=0.019*mol*L^-1#. What is #pH# for this solution?
Sign up to view the whole answer

By signing up, you agree to our Terms of Service and Privacy Policy

Sign up with email
Answer 2

[ [HO^-] = \sqrt{K_b \cdot \text{concentration}} = \sqrt{4.1 \times 10^{-4} \cdot 0.910} ] [ [HO^-] \approx 0.018 , \text{mol/L} ]

Sign up to view the whole answer

By signing up, you agree to our Terms of Service and Privacy Policy

Sign up with email
Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

Not the question you need?

Drag image here or click to upload

Or press Ctrl + V to paste
Answer Background
HIX Tutor
Solve ANY homework problem with a smart AI
  • 98% accuracy study help
  • Covers math, physics, chemistry, biology, and more
  • Step-by-step, in-depth guides
  • Readily available 24/7