They have gaven me the answer incorrect twoce they are jsut waisting my quwsrions olease help MISSED THIS? Watch

KCV: Finding. $pH$ and $pH$ Changes in Buffer Solutions.

IWE: Calculating the pH Change in a Buffer Solution after the Addition of a Small Amount of Strong Acid or Base

; Read Section $17\mathrm{.}2.$ You can click on the Review link to access the section in your e Text.

A $120\mathrm{.}0mL$ buffer solution is $0\mathrm{.}110M$ in $N{H}_3$ and $0\mathrm{.}130M$ in $N{H}_{4}Br.$

Part A

What mass of $HCl$ can this buffer neutralize before the $pH$ falls below $9\mathrm{.}00?$

Express the mass in grams to three significant figures.

View Available Hint$($s$)$

$$

Previous Answers Request Answer

Incorrect; Try Again

To solve for the mass of $HCl$ required to bring the $pH$ to $9\mathrm{.}00,$ set up a Henderson$-$Hasselbalch equation base$]/[$acid$]).$ Adding acid will increase the value of the denominator and decrease the value of the numerator in the log fraction.

The value of $K_b$ is given, so you will need to convert the value either to $p{K}_b$ then $p{K}_a$ or to $K_a$ then $p{K}_a.$

You may want to review Hint $1.$ How to approach the problem.

Part B

If the same volume of the buffer were $0\mathrm{.}260M$ in $N{H}_3$ and $0\mathrm{.}390M$ in $N{H}_{4}Br,$ what mass of $HCl$ could be handled before the $pH$ falls below $9\mathrm{.}00?$

Express the mass in grams to three significant figures.

View Available Hint$($s$)$

Previous Answers $$ Previous Answer

$x$ Incorrect; Try Again

Set up the Henderson$-$Hasselbalch equation $($ base