chem mole helpp!!20pt

145. C

(COOH)2 + 2NaOH → (COONa)2 + 2H2O
Volume of NaOH used in the runs (cm³): 22.0 (rejected), 20.0, 19.9, 20.1
Reasonable average volume of NaOH = (20.0 + 19.9 + 20.1)/3 = 20 cm³
moles of NaOH = 0.1 x 0.02 = 0.002 mol
moles of diluted acid = 0.002 x (1/2) = 0.001 mol
moles of original acid = 0.001 x 10 = 0.01 mol
Molarity of original acid = 0.01/0.025 = 0.40 M


146. B

H2SO4 + 2NaOH → Na2SO4+ 2H2O
moles of H2SO4 = (9.8/98) x 0.03 = 0.003 mol
moles of NaOH = 0.003 x 2 = 0.006 mol
Molarity of NaOH = 0.006/0.025 = 0.24 M


147. C

2NaOH + H2SO4 → Na2SO4+ 2H2O
moles of NaOH = 0.9 x 0.2 = 0.18 mol
moles of H2SO4 = 0.9 x 0.1 = 0.09 mol
Both NaOH and H2SO4 are completely reacted.
No. of moles of Na2SO4 formed = 0.09 mol
Conc. of Na2SO4 = 0.09/(0.1+0.2) = 0.3 M


150. A

NaOH + HCl → NaCl + H2O
moles of HCl = 0.550 x (28.0/1000) = 0.0154 mol
moles of NaOH = 0.0154 mol
moles of hydroxide ions in filtrate = 0.0154 mol


151. C

2NaOH + NiSO4 → Ni(OH)2↓ + Na2SO4
moles of NaOH reacted = 1 x 0.025 - 0.0154 = 0.0096 mol
moles of NiSO4 = 0.0096 x (1/2) = 0.0048 mol
Molarity of NiSO4 = 0.0048/0.025 = 0.192 M


152. A

A. complete
CH3COOH + NaOH → CH3COONa + H2O
Actual mole ratio CH3COOH : NaOH = 0.1 x (20/1000) : 0.1 x (20/1000)= 1 : 1
The mole ratio is equal to that shown in the equation.

B. NOT
H2SO4 + Na2CO3 → Na2SO4 + H2O + CO2
Actual mole ratio H2SO4 : Na2CO3 =0.1 x (25/1000) : 0.2 x (25/1000) = 1 : 2
But mole ratio in equation = 1 : 1

C. NOT
2HCl + Na2CO3 → 2NaCl + H2O +CO2
Actual mole ratio HCl : Na2CO3 = 0.1 x (20/1000) : 0.1 x(20/1000) = 1 : 1
But mole ratio in equation = 2 : 1

D. NOT
HCl + NH3 → NH4Cl
Actual mole ratio HCl : NH3 = 0.1 x (25/1000) : 0.2 x (25/1000) = 1: 2
Nut mole ratio in equation = 1 : 1


154. A

Na2CO3 + 2HCl → 2NaCl + H2O +CO2
moles of HCl = 1 x (50/1000) = 0.05 mol
moles of Na2CO3•nH2O = 0.05 x(1/2) = 0.025

Molar mass of Na2CO3•nH2O :
23x2 + 12 + 16x3 + n(1x2 + 16) = 3.1/0.025
106 + 18n = 124
n = 1