What is the concentration of formate ion in a solution that is 0.10 M formic aci

Question

What is the concentration of formate ion in a solution that is 0.10 M formic acid and 0.20 M HCl?

A soluton of the salt, ammonium formate. (CVH.CHO, s A solution of the salt, ammonium formate, (NH4)CHO2 is: very acidic very basic slightly acidic slightly basic E the pH of this salt solution cannot be determined with the information What is the concentration of formate ion, CHO2, in a solution that is 0.10 M HCHO2 (formic acid) and 0.20 M HCl? Given formic acid Ka 1.7 x 104 (Hint: treat as a common ion effect) 8.5x105 1.7x104 2.0x102 5.9x10-11 What is the pH of a solution of 0.10 M acetic acid, (HC2H,O2), and 0.20 M sodium acetate, (Na C2H,02)? (acetic acid Ka 1.7x10) A 8.93 4.76 5.07

Explanation / Answer

Solution
Given data
0.1M HCHO2
0.20 M HCl
Ka = 1.7*10^-4
HCl is the strong acid therefore it dissociate completely to form the 0.20 M H3O+
Lets use this concentration in the ICE table and calculate the equilibrium concentration of the HCO2-
     HCHO2 + H2O ----- >    H3O^+    +   HCO2^-
I     0.10                              0.20 M          0
C    -x                                    +x             +x
E    0.1-x                            0.20+x          x
Lets write the Ka equation
Ka =[H3O+][HCO2-]/[HCHO2]
Lets put the values in the above formula
1.7*10^-4 = [0.20+x][x]/[0.10-x]
1.7*10^-4 * 0.10-x = [0.20+x][x]
By solving this equation using the quadratic equation we get
X= 8.5*10^-5
X=[HCO2-] = 8.5*10^-5
Therefore the concentration of the formation ion at equilibrium = 8.5*10^-5
Hence option ‘A’ is the correct answer

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