<p>Please help me with acids and bases because I'm still not grasping the whole concept. can someone explain the reasoning behind the questions below:
1) Which of the following reagents could not be added together to make a buffer solution?
a) NaOH(aq) and CH3COOH(aq)
b) NaCH3COO and CH3COOH
c) NaOH and NaCH3 (answer)
d) NH4Cl and NH3</p>
<p>2) Which salt does not form an acidic solution in water?
a) MgCl2
b) Na2CO3 (answer)
c) FeCl3
d) NH4NO3</p>
<p>1) Buffers are made with weak acids/bases and their conjugates-- which is not the case in part c.</p>
<p>2) The sodium ion is a spectator, so don't worry about it. Since carbonate is basic, the salt obviously forms a basic solution in water.</p>
<p>The first one.
Buffers are solutions that resist changes in pH.
Notice that besides the answer, all of the others have an acid and a base. When you mixed them together, the pH will level off. When you add something, the pH will level off.
But Choice C gives NaOH (strong base) and NaCH3 (salt which will dissociate)
Na+ + CH3-
Na+ will make NaOH in aqueous solution. Strong base. So that mixture will not level off the pH. Not a good buffer.</p>
<ol>
<li>MgCl2 --> Mg2+ + 2Cl-
Will make MgOH2(Strong base) and HCl(strong acid) in water, so that would result in neutral solution.
FeCl3 --> Fe3+ + 3Cl-
Will make Fe(OH)3(not a strong base) and HCl(strong acid) in water, so that would result in acidic solution.
NH4NO3 --> NH4OH + NO3
Will make NH4OH(not a very strong base) and HNO3(strong acid) in water, so that would result in acidic solution.
Na2CO3 --> NaOH + H2CO3
Will make NaOH(very strong base) and H2CO3(weak acid) in water, so that would result in base solution.</li>
</ol>
<p>Hope this helps..</p>