someone help meon these two AP chem problems

Test Preparation AP Test Preparation
1

<p>I don't get this problem...simple acid/base?
A solution prepared by mixing 10ml of 1M HCl and 10ml of 1.2M NaOH has a pH of?</p>

<p>The answer is 13, but I don't know how.</p>

<p>Which of the following salts form a basic solution when dissolved in water?</p>

<p>a)NaCl
b) (NH4)2SO4
c) CuSO4
d) K2CO3
e) NH4NO3</p>

<p>I don't get it, don't all of them dissociate 100%?</p>

2

<p>Question 2:</p>

<p>The answer is K2CO3.</p>

<p>K2CO3 is formed from H2CO3 and KOH. This is a strong base and a weak acid - this produces a basic salt.</p>

3

<p>Question 1:</p>

<p>You have .010 mol HCL and .012 mol NaOH.
.012 - .010 = .02 mol NaOH excess = .02 mol OH-</p>

<p>[OH-] = .02/20 = .10 M
pOH = -log(.10) = 1
pH - 14 - 1 = 13</p>

4

<p>If you don’t know where the above equations came from, here’s some help:</p>

<p>Q1:</p>

<p>M1V1 = M2V2 // mol1 = mol2 at equilibrium

  • Solve for mol HCL and mol NaOH
  • Because they are strong acids/strong bases, they react completely to form H20, and you are left with .02 mol NaOH (which disassociates into Na+ and OH- in equal molar ratios)</p>

<ul>
<li>Convert mol OH- to <a href=“keeping%20in%20mind%20that%20volume%20changed”>OH-</a></li>
<li>pOH = -log[OH-] = 1</li>
<li>pH = 14-pOH = 13</li>
</ul>