Acid-Base

which of the following formulas could be used to find the  $\left[OH^-\right]\$ at equilibrium for weak base problems? knowing that weak base ionizes by less than 5%. 

•  $-\log\sqrt{K_b.\left[weak\ base\right]_0}$  

•  $\sqrt{K_a.\ \left[weak\ base\right]_0}$  

•  $-\log\sqrt{K_a.\ \left[weak\ acid\right]_0}$  

•  $\sqrt{K_b.\left[weak\ base\right]_0}$  

which of the following formulas could be used to find the [H⁺] at equilibrium for WEAK ACID problems? assuming that this weak acid will ionize by less than 5%.

• $-\log\sqrt{K_a.\left[weak\ acid\right]_0}$

• $\sqrt{K_a.\left[weak\ acid\right]_0}$

• $\sqrt{K_b.\left[weak\ base\right]_0}$

• $\sqrt{K_a.\left[weak\ base\right]_0}$

What does 5% Rule mean?

• when you carry out a calculation that does not drop the 'minus x' from the denominator while finding pH of weak acid or base.

• when you use the approximation method that drops the 'minus x' from the denominator while finding pH of weak acid or base assuming that the weak acid or base dissociates by MORE than 5%.

• when you use the approximation method that drops the 'minus x' from the denominator while finding pH of weak acid or base assuming that the weak acid or base dissociates by LESS than 5%.

• When you have a strong acid that dissociates by more than 5%.

If the concentration of strong monoprotic acid is given (HA) how could you find the  $\left[H^+\right]$ in the solution.

•  $\left[H^+\right]\ =\ \left[HA\right]_0$  
  

•  $\left[H^+\right]\ =2\ .\left[HA\right]_0$  

•  $\left[H^+\right]\ =\ \left[HA\right]_0-X$  

•  $\left[H^+\right]\ =\ \frac{\left[HA\right]_0}{2}$  

If the concentration of  $Sr\left(OH\right)_2$ is given, how could you find the  $\left[OH^-\right]$ in the solution? 

•  $\left[OH^-\right]=\left[Sr\left(OH\right)_2\right]_0$  

•  $\left[OH^-\right]=\frac{\left[Sr\left(OH\right)_2\right]_0}{2}$  

•  $\left[OH^-\right]=\left[Sr\left(OH\right)_2\right]_0\ +2$  

•  $\left[OH^-\right]=2.\ \left[Sr\left(OH\right)_2\right]_0$  

Which formula is related to the percent ionization of weak acids?

• $\frac{\left[weak\ acid\right]_0\ }{\left[H^+\right]_{at\ equilibrium\ }}x100$

• $\frac{\left[weak\ acid\right]_0}{100\ x\ \left[H^+\right]}$

• $\frac{\left[H^+\right]_{at\ equilibrium\ }}{\left[weak\ acid\right]_0\ }x100$

• $\sqrt{\left[H^+\right]_{at\ equilibrium\ }\ x\ 100}$

which of the following statement  is NOT correct?

• As  $K_a$  value increases  $pK_a$  value decreases the stronger the acid is. 

• As  $K_a$  value decreases  $pK_a$  value decreases the weaker the acid is. 

• As  $pK_a$  value increases  $K_a$  value decreases the weaker the acid is.

• The higher the  $K_a$  the lower the  $K_b$  

The relation between pH and pOH is

• pH x pOH = 14

• pH + pOH = 14

• pH x pOH = $10^{-14}$

• pH + pOH = $10^{-14}$

Which of the following formula shows the relation between Hydronium and Hydroxide ions in any acidic or basic solution?

• $\left[H^+\right]+\left[OH^-\right]=10^{-14}$

• $\left[H^+\right]\ .\ \left[OH^-\right]=10^{-14}$

• $\frac{\left[H^+\right]}{\left[OH^-\right]}=10^{-14}$

• $-\log\left[H^+\right]\ .\ -\log\left[OH^-\right]=10^{-14}$

What is $K_{w\ }$ ?

• Is the dissociation constant of weak acid reaction.

• Is the dissociation constant of weak base reaction. 

• Is the dissociation constant of the Auto Ionization of water. 

• Is the dissociation constant of any equilibrium reaction.