When to double moles

[VGonzalez]

When do you know to double moles or multiply an answer to get the next whole number. In the lecture we had to multiply 1.33 by 3 but if a number is like 1.1 or 1.9 do we still have to or can we round it? Are there any general rules?

[Josephine Chan 1B]

I think in one of the lectures he said that if the number is less than 0.05 from the closest whole number, then its close enough to round it. If not then you probably just have to keep multiplying until you get close enough to the next whole number

[Daniela Alvarado 3B]

Yeah I believe if it’s off and multiplying it will make only make it off by less than .05 then that’s when you multiply it, but all 3 numbers have to be super close to a whole #

[Dong Hyun Lee 4E]

When trying to balance equations, you might run into numbers that are decimals. To turn these into whole numbers, you will want to multiply something that will result in all the coefficients becoming whole. As an example in class when left with a coefficient like 1.33, multiplying by 3 will land you with 3.99 or approximately 4. Another example would be 2.5 which you could multiply 2 to get rid of the decimal or 1.1 in another case could simply be multiplied by 9 which would take it to 9.9 or just close enough to ten for you to proceed with the problem.

[Andrew Bennecke]

Usually if the amount of moles is a decimal, which doesn't appear to multiply easily with the ithers in the compound, you may still have to divide each of the mole values by the smallest mole value.

[Lynsea_Southwick_2K]

If the value was 1.37 and it has to be multiplied to get closer to a whole number, what would you multiple it by? x 3 would equal to 4.11, but x 2 would be 2.74.

[Niveda_B_3I]

It's never going to be completely accurate. You just have to round to the nearest whole number.

[Christopher Wendland 4F]

If it is less than .1 away from a whole number we are able to round it.

[Erin Nash - 4G]

You would like to get within .1 (or closer) to a whole number before you round so that the empirical formula is all integers. Many times we get answers such as 1.33 so it's easier for us to find the empirical formula (multiplying by 3).

[taywebb]

Just double checking that if I had 1.1 of something rounding to 1 would be ok, even though it is more than 0.05?

[Daisylookinland]

Yes I believe so because if you were to multiply 1.1 by 9 to get closer to a whole number you would still be .1 away from the nearest whole number.

[Ronald Thompson 1F]

Divide by the smallest value, then usually the decimals are close enough to whole numbers that it is best to just round. There are special cases however

[Anmol_cheema_2F]

If the number is within about .1, then round to the nearest whole number.

[davidryan3f]

You can round up or down if it is within .1 of the nearest whole number.