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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?
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).
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.
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.
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.
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!
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