AP Chem significant digits

<p>How many significant digits do you use for exponents,
for example if you are given 0.0015, and you have to raise e to the power of that, how many significant digits are in the final answer.</p>

<p>For pH, it’s like the digits in the decimal of the log</p>

<p>i don’t get it</p>

<p>for 0.0015 it’d be 1.5 x 10^whatever or 1.5e because 15 are the significant figures. The only time 0 is a sig fig is if it is in the middle of a number or it is the last digit of a decimated number.</p>

<p>no but what about exponentiation
say you are given 0.0015 M is the concentration of H+. You want to find pH so that’s -log[0.0015] = 2.8239087…
Where do you round it?</p>

<p>You round it to two places after the decimal point for pH values (2.82).</p>

<p>No, wouldn’t it be 2.8…because 1 and 5 are the only significant digits?</p>

<p>Sig figs for pH are counted AFTER the decimal. For example:</p>

<p>1.0E-2 </p>

<p>Take the negative log to find pH</p>

<p>pH = 2.00 </p>

<p>The “2” is considered the “exponent,” so sig figs are counted AFTER the decimal.</p>

<p>thank you.</p>