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### Empirical Coefficients

Posted: Wed Oct 04, 2017 11:11 pm
Sometimes when I solve for the empirical formula I get moles like 3.1 or 2.9. Looking at the answers, I found out that rounds to 3. After what decimal digit (3.15 or 3.2) should I multiply all the moles by a constant to get better whole numbers?

### Re: Empirical Coefficients

Posted: Wed Oct 04, 2017 11:54 pm
Typically, you will get numbers that are very close to a whole number such as 1.97 or 3.08 which you would round to 2 and 3. In many of the problems I have done so far that I've had to multiply in order to get a whole number, I've gotten numbers like 2.67, 1.33 and 3.75 which can easily be multiplied to get a whole number (2.67 x 3, 1.33 x 3, 3.75 x 4).

### Re: Empirical Coefficients  [ENDORSED]

Posted: Thu Oct 05, 2017 9:04 am
Generally, anything that doesn't seem like it can be easily multiplied into another whole number (ex: 1.5 x 2, 2.67 x 3) can be easily rounded to its nearest integer. This usually just happens due to rounding errors with sig figs so I wouldn't worry too much. They are almost always apparent what they should round to.

### Re: Empirical Coefficients

Posted: Thu Oct 05, 2017 5:02 pm
Yeah that's what I learned in chemistry class, you round down when it's bellow 1.3, and round up when it's 1.8, but when its 1.5 multiply by 2, and when its 1.6 multiply by 3.

### Re: Empirical Coefficients

Posted: Thu Oct 05, 2017 5:40 pm
When the answer you acquire is close to a whole number such as 2.9 it is better to round up to 3 and not having to multiple by another number as it already is a whole number.

### Re: Empirical Coefficients

Posted: Thu Oct 05, 2017 6:19 pm
As far as I know, if the number is within .1 from a whole number than you would just round to that whole number. However if its more than that you would need to multiply it by a number to get it to a whole number. So if it is .25 than you would multiply by 4 or if its .5 you would multiply by 2 and etc.

### Re: Empirical Coefficients

Posted: Thu Oct 05, 2017 6:58 pm
Yeah I agree. You mainly want to round when you get a number ending in like .5, .333, .666. etc. Other then that, if the number is below .5 in the tens place then round down and if above, round up.

### Re: Empirical Coefficients

Posted: Fri Oct 06, 2017 1:05 pm
Generally I would round to the nearest whole number if its +/- 0.1 from a whole number. Often times numbers are off a little due to rounding errors.

### Re: Empirical Coefficients

Posted: Fri Oct 06, 2017 1:18 pm
From what I learned you round up when its bigger than .5 and round down when its smaller than .5

### Re: Empirical Coefficients

Posted: Fri Oct 06, 2017 7:06 pm
If the answer is .1 away from a whole number, round accordingly. If it isn't then multiply all mole ratios so they are close enough to whole numbers. For example, if one ratio is 2.25, multiply all the ratios by 4 to get whole numbers.

### Re: Empirical Coefficients

Posted: Fri Oct 06, 2017 9:42 pm
nanditasundarapandian1D wrote:From what I learned you round up when its bigger than .5 and round down when its smaller than .5

but what if the last digit is exactly 5?

### Re: Empirical Coefficients

Posted: Sun Oct 08, 2017 3:32 pm
yifeiwang wrote:
nanditasundarapandian1D wrote:From what I learned you round up when its bigger than .5 and round down when its smaller than .5

but what if the last digit is exactly 5?

When we discussed rounding in my discussion section, we talked about how if it's exactly .5, you would round to the nearest even number, so if it was 3.25, you would round to 3.2, and if it was 3.35, you would round to 3.4!

### Re: Empirical Coefficients

Posted: Wed Oct 11, 2017 10:17 pm
Thanks guys.