Hey there!
Cu(CN)₂
Find the molar mass.
Cu: 1 x 63.546 = 63.546
C: 2 x 12.01 = 24.02
N: 2 x 14.07 = 28.14
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115.706 grams
The mass of one mole of Cu(CN)₂ is 115.706 grams.
We have 4 moles.
115.706 x 4 = 463
4.00 moles of Cu(CN)₂ has a mass of 463 grams.
Hope this helps!
Molarity=(initial molarityxinitial volume)/final volume
M=(3.5x25.4)/166.7=0.533 M
The balanced equation for the acid base reaction is as follows
NaOH + HCl ---> NaCl + H₂O
stoichiometry of NaOH to HCl is 1:1
the number of NaOH moles reacted - 0.200 mol/L x 0.0250 L = 0.005 mol
according to molar ratio
number of NaOH moles reacted = number of HCl moles reacted
therefore number of HCl moles - 0.005 mol
volume of 30.0 mL contains 0.005 mol
therefore 1000 mL contains - 0.005 mol / 0.030 L = 0.167 M
concentration of HCl is 0.167 M
Solution:
At the equivalence point, moles NaOH = moles benzoic acid
HA + NaOH ==> NaA + H2O where HA is benzoic acid
At the equivalence point, all the benzoic acid ==> sodium benzoate
A^- + H2O ==> HA + OH- (again, A^- is the benzoate anion and HA is the weak acid benzoic acid)
Kb for benzoate = 1x10^-14/4.5x10^-4 = 2.22x10^-11
Kb = 2.22x10^-11 = [HA][OH-][A^-] = (x)(x)/0.150
x^2 = 3.33x10^-12
x = 1.8x10^-6 = [OH-]
pOH = -log [OH-] = 5.74
pH = 14 - pOH = 8.26
