I want to make sure my answers are correct to the first and third question. For

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I want to make sure my answers are correct to the first and third question. For the second question, I need help elaborating on my answer. Basically, why would two of the same buffer solutions with different molarities have the same pH? I want to make sure my answers are correct to the first and third question. For the second question, I need help elaborating on my answer. Basically, why would two of the same buffer solutions with different molarities have the same pH? I want to make sure my answers are correct to the first and third question. For the second question, I need help elaborating on my answer. Basically, why would two of the same buffer solutions with different molarities have the same pH? CHEM 1152L Lab Manual Page 49 ost-Lab Questions What is the pH of the 0.1 M hydrochloric acid and 0.1 M acetic acid solutions? Are they the same? Why or why not? NopM hydrochlonic aud has a slightly lowerpH than 0.1 oue tic aud. This is becaus e Hu is a stronger dud 2) Compare the initial pH's of the low concentration and high concentration acetic acid buffer sol'ns. Are they the same? Why or why not? They are relatively the same. Though they are difterenf moles, the chemial elenenrs rwotved dre the 5ome however. the concentr atrions are just different 3) Compare the volumes of base added to the 0.1 M acetic acid -sodium acetate buffer and 0.5 M acetic acid - sodium acetate buffer. Are they the same? Why or why not? Which one is a better buffer? NO, they are different. Beccuse the molanity is higher in the 0.5 M acehc aud-sodium acetate butter. Tne higher the Concentraton of me buttening molecules, The more base ue wed (Naot) Can be absorbed. The 05 M ncehc ocid-sodium acetate butter is a better bufter because it has ar higher capauty

Explanation / Answer

HCl is strong acid while acetic acid is weak acid. Whether an acid is strong or weak depends on Ka value. High Ka values indicate lower pH and lower Ka values indicate high pH.

for example HCl is strong acid and ionizes completely. HCl+ H2O --------->H3O++Cl-

[H3O+]=0.1, pH= -log [H3O+]= 1

acetic acid has Ka value of 1.8*10-5, ionization of acetic acid is CH3COOH+ H2O ------->CH3COO- + H3O+

Ka= [CH3COO-] [H3O+]/[CH3COOH]= 1.8*10-5, let x= drop in concentration of 0.1M acetic acid to reach equilibrium

at equilibrium, [CH3COO-]= [H3O+]=x

hence x2/(0.1-x)=1.8*10-5, when solved using excel, x= 1.35*10-3, [H3O+]= 1.35*10-3, pH= 2.87

hence pH of 0.1M HCl and pH of 0.1M acetic acid is not same.

2. concentration of 0.5M acetic acid and sodlum acetate bufffer is higher than that of 0.1M acetic acid and sodium acetate buffer. since higher concentration of buffer requires higher concentration of NaOH according to the reaction

CH3COOH+ NaOH-------->CH3COONa.

the buffering capacity of 0.5 buffer is more than that of 0.1M since the capacity of 0.5M buffer is more than that of 0.1M

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