<p>Hey guys, Im preparing for my test tomorrow, and im stuck on this problem. Any help would be appreciated.</p>
<p>Citric Acid, which can be obtained from lemon juice, has the molecular formula C6H8O7. A 0.250-g sample of citric acid dissolved in 25.0 mL of water requires 37.2 mL of 0.105 M NaOH for complete neutralization. How many acidic hydrogens per molecule does citric acid have?</p>
<p>Zumdahls 5e, Pg. 185 #95</p>
<p>This is so funny, because I remember this exact problem from last year..</p>
<p>(Sorry.. this post was absolutely useless to you.. :o)</p>
<p>Lol, wanna look up those notes?? </p>
<p>..jk</p>
<p>Any idea on how to set up the problem?</p>
<p>My guess (and I haven't taken AP Chem in two years) would be to calculate the number of OH- ions in the NaOH that was added. This will equal the total number of acidic hydrogens in the total volume of citric acid. Divide by the number of molecules (moles * Avagadro's number) to get # of acidic hydrogens per molecule. I don't know that you need to use the volume of water the citric acid is dissolved in since I don't see how the molarity of the citric acid solutions is necessary if you know the mass.</p>
<p>Thanks, let me try that. FYI, the answer is 3 acidic hydrogens per molecule of citric acid.</p>
<p>If you guys were wondering the answer ( You probly werent) here it is (I finally got it):</p>
<p>Question:
Citric Acid, which can be obtained from lemon juice, has the molecular formula C6H8O7. A 0.250-g sample of citric acid dissolved in 25.0 mL of water requires 37.2 mL of 0.105 M NaOH for complete neutralization. How many acidic hydrogens per molecule does citric acid have?</p>
<p>Answer:</p>
<p>.0372L * .105M NaOH = .003906 mols NaOH</p>
<p>(.250g C6H8O7) / .003906 mols NaOH = 64.0g/mol </p>
<p>(192.124 g C6H8O7) / 64.0g/mol</p>
<p>Answer= 3 acidic hydrogen molecules per molecule of citric acid.</p>