Chemistry Problems Help

Test Preparation SAT Subject Test Preparation
1

<p>Na2CrO4, a soluble yellow solid
PbCrO4, an soluble yellow solid
NaNO3, a soluble white solid
Pb(NO3)2, a soluble white solid</p>

<p>(A) Yellow solid and colorless solution
(B) Yellow solid and yellow solution
(C) White solid and colorless solution
(D) No solid and yellow solution
(E) No solid and colorless solution</p>

<ol>
<li><p>Observed when 1 mol of Na2CrO4 and 2 mol of Pb(NO3)2 are mixed with 1 L of water</p></li>
<li><p>Observed when 3 mol of Na2CrO4 and 1 mol of Pb(NO3)2 are mixed with 1 L of water</p></li>
</ol>

<p>This is from the SAT subject test collegeboard book. I put B for 4 and A for 5 but the answer key says 4 is A and 5 is B. Can someone please explain why those are the correct answers? And when will a solution have a color, in this case yellow?</p>

2

<p>Did you copy these right? If they are ALL soluble and you are only getting soluble answers then your answer would either be D or E to both. I’m also pretty sure PbCrO4 is NOT soluble.</p>

<p>Assuming PbCrO4 is NOT soluble: The chromate ion is yellow itself in solution.
With 4 you DON’T have excess chromate, meaning the solution will be colorless but you will get a yellow solid (PbCrO4), this leads me to pick answer A. </p>

<p>With 5 you DO have excess chromate, meaning the solution will be yellow AND you’ll get a yellow solid (PbCrO4), this leads me to pick answer B.</p>