Question

Calculate [OH ^-] and pH for each of the following solutions.



(a) 0.0092 M CsOH

[OH-] =  M

pH =

(b) 0.0335 g of RbOH in 520.0 mL of solution

[OH -] =  M

pH =

(c) 62.6 mL of 0.00552 M Ca(OH)₂ diluted to 900 mL

[OH -] =  M

pH =

(d) A solution formed by mixing 64.0 mL of 0.000150 M Ca(OH)₂ with 89.0 mL of 4.3 x 10^-3 M CsOH

[OH -] =  M

pH =

Answer 1

Solution: AP) lu a given question, Molarity of 65001 sol"E 0.0092.74 CSOH is a strong base ie (oh discount i'u sol 100%. CS OH ist + 011" → Solot = 0.0092m pH + pol 314 --(I) pon = -log[cH = -log [000922 poit = 2.036 From eva cis pH + 2.036 = 14 pH = 14 - 2.036 [ PH = 11-961 1 6) Guiven, mass of RbOH = 0.03359 volume of sci" = 520 mb we know that . molarity of solution no. of moles of selute leer Yolume of solution4(**) no. of moles of Souk (kbor) mass_ moluym4s1 0.0335 102415 = 0.0003269 must

From ci) molarity of Solwicy G. ROOH = no. of moles of Rboh X 1000 Volume of soll (ver) 10003269 xlogo 520 0.00062077 = is strong base lie it desso late 100). in solution ROCH = R67 + OH- so [OH-] = 0.0006287 PH + pol = 14 -13) pOH = -log Conta = -log(0.0006207) pOH = 3.2 the PH = 14- pon = 14-32 1 pH = 10.00 c) Griven Molarity of (2006), sola in 62.6 ML = 0.00552 Before dilution het Molarity of Lalon), 501"= no of us des of ) Vei" by soy many no. of undles of Laoh), in sol" - molarity & volt a col found) 000652 x 626

After ditution no of to Total volume of solº = 900+62:6 So Now Y lors = 962.6 ml Molarity of cpH) soľ - no. of moles Toral vot of solen) .000345 mot 9 62.6 → =0.000 350 m CO(OH), is strong base ie it dissociate 100). in soia wool Ca(OH)2 = ca²tt 1204 so com'] = 2* 0.000359 COH) = 70168.74 X 104 = 0.0007168 pH + pol = 14 - ci). pom = -log( 0.0007160) pOH = 3.145 PH = 14 - pol po = 14- 3.145 PH = 10.06

d) buren First sol, vou of ocool50m (atH) a sol = 64 mL no. of moles of calo H), salu sol = Molarity & vol of sol" looo = 0.00015 X64 1000 VEND = 000 9056 wol Second solut" vol of 0.0043 m (S OM SOL"= 89 mL no.of moles of 18 OH iu sol*= motarily x VOL 8 502 - loco =:0043 x 89 looo both sol ution = 0.0003027 After mixing of both sol, Total volume = 64.709 = 153 WL Total no. of notority of ools. Total no.of moles of soc"= 0.009056 +0.0003827 = 0.010

1000) Molarity of sol" - Total no of mores . Total wo (** of 500m = 0·01 Yloud 153 00655 m le → LalOH) is 0H) Both strong You (30H 0 8V op ons Calon), = Combat 2011 so LOR= 3 *0.0655 - [ok] = 0. 1965 m - pH it port = 14 por = -log[or] - 0.71 pH = 14-0:11 1 PH 13:29