<p>OH- + <em>(1)</em> → CrO4 (2-) + H+</p>
<pre><code> (2)
</code></pre>
<p>CrO4 (2-) + H+ → BaCrO4 (s)</p>
<pre><code> (3) forward
</code></pre>
<p>BaCrO4(s) ↔ Ba (2+) + Cr2O7(2-) + H2O
(4) reverse</p>
<p>Ba (2+) + Cr2O7 + H2O → BaSO4(s) + <em>(5)</em> + H2O </p>
<p>Choices for all question numbers 1, 2, 3, 4, and 5 were:
A) Cr2O7 (2-)
B) H+
C) OH-
D) Cr (3+)
E) Ba (2+)</p>
<p>The answers were: 1-A, 2-E, 3-B, 4-C, 5-D
Only number 2 seems obvious to me, but I don't understand the other answers. I don't think it's a redox reaction though. These are questions 5-9 in the REAL SAT II Chemistry test. They were the most missed questions. Can someone please help!!! (I'm taking SAT II on Saturday and I'm desperate)</p>