Chapter 11

# Chapter 11 - 11.4(a)The reaction is HCN(aq H 2 O(l H 3 O(aq...

This preview shows pages 1–4. Sign up to view the full content.

11.4 (a) The reaction is 2 3 HCN(aq) H O(l) H O (aq) CN (aq). + - + + Concentration 1 (mol L ) - HCN(aq) + H 2 O(l) H 3 O + (aq) + CN (aq) - initial 0.075 0 0.060 change - x + x + x equilibrium 0.075 - x x 0.060 + x K a = ] [ ] ][ [ 3 HCN CN O H - + = ) 075 . 0 ( ) 060 . 0 )( ( x x x - + = 4.9 x 10 -10 x = [[H 3 O + ] 6.1 x 10 -10 mol . L -1 (b) 0.30 M NaCl will have no effect: Concentration 1 (mol L ) - NH 2 NH 2 (aq) + H 2 O(l) a NH 2 NH 3 + (aq) + OH (aq) - initial 0.20 0 0 change - x + x + x equilibrium 0.20 - x x x 2 3 b 2 2 2 6 7 4 1 [NH NH ][OH ] [NH NH ] [OH ] 1.7 10 0.20 [OH ] 3.4 10 5.8 10 mol L + - - - - - - - = × = = × = × K 14 11 1 w 3 4 1.00 10 [H O ] 1.7 10 mol L [OH ] 5.8 10 - + - - - - × = = = × × K (c) Setup is similar to part (a). 10 3 a 10 3 10 1 3 [H O ][CN ] ( )(0.030 ) 4.9 10 [HCN] (0.015 ) [H O ][0.030] 4.9 10 (0.015) [H O ] 2.5 10 mol L + - - + - + - - + = × = = - × = × x x K x

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
(d) When the concentrations of a weak base and its conjugate acid are equal, the pOH equals the p K b . Therefore, the pOH of hydrazine = p K b = 5.77, and 8.23 9 1 3 pH 14.00 pOH 14.00 5.77 8.23 [H O ] 10 5.9 10 mol L + - - - = - = - = = = × 11.12 HA = acetylsalicylic acid A - = conjugate base of acetylsalicylic acid 2 3 HA(aq) H O(l) H O (aq) A (aq) + - + + 4 a 3.2 10 - = × K We will use the following formula to evaluate the ratio of [A ] - to [HA] at equilibrium: a [A ] pH p log [HA] - = + K The formula is derived in this way: 3 a a 3 [H O ][A ] [HA] [HA] [H O ] [A ] + - + - = = K K a a a [HA] pH p [A ] [HA] p log [A ] [A ] p log [HA] - - - = = - = + K K K Given that pH = 4.13 and K a = 3.2 x 10 -4 (pKa = 3.49) 4.13 = 3.49 + log ] [ ] [ HA A - ] [ ] [ HA A - = 4.37
11.36 (a) It is a weak base because the stoichiometric point pH 5.0 < 7.0 (b) pH = 10; pOH = 4; [OH

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### Page1 / 8

Chapter 11 - 11.4(a)The reaction is HCN(aq H 2 O(l H 3 O(aq...

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online