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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: bamcanfly on September 07, 2009, 01:49:28 AM

Title: Need help with significant figures
Post by: bamcanfly on September 07, 2009, 01:49:28 AM: I am a Junior taking chemistry and so far i understand all the basics of chemistry except for significant figures. Whenever i solve a problem my teacher says I got it right except i forgot about significant figures. I would really appreciate it if someone explained this to me.
Title: Re: Need help with significant figures
Post by: Fridushka on September 07, 2009, 03:21:42 AM: The principle is that you have to round so that it contains only sig. fig.
Sig. fig. : the certain values and the 1st uncertain value
In case you are measuing a solution in a buret, as i know the buret has an error of +/- 0.02, here there is 2 certain digits and 1 uncertain (3 sig. fig.)!
the uncertain 1 is the last digit and the certain are the 1st 2
if you have 400 and there are 3 sig. fig., which are the certain digists and uncertain values?
if you have 450...2 diffrent cases, in the first is +/-10 and in the 2nd case +/-2..same question!

Do this, Good luck:)!
Title: Re: Need help with significant figures
Post by: Fridushka on September 07, 2009, 03:31:08 AM: Well i would like to add something else..
about the scientific notation...
if you number is 400 and you have 3 sig. fig.
you can write in different ways, such as 40.0 x 10¹ or 4.00 x 10²
if you number is 400 and you have 2 sig. fig.
you can write in the following ways 4.0 x 10² or 40 x 10¹
so what if you have 1 sig fig of the same number?

I would like to add inform you something else
0.1003 ..here there is 4 sig fig and the 1st 0 decide the position of the sig fig!
what if you have 0.034?
Title: Re: Need help with significant figures
Post by: bamcanfly on September 07, 2009, 08:42:49 PM: 3 sig. fig.?
Title: Re: Need help with significant figures
Post by: Fridushka on September 08, 2009, 02:30:13 AM: what do you mean by your question!!?!
Title: Re: Need help with significant figures
Post by: Fridushka on September 08, 2009, 02:30:54 AM: Did you understand anything or ?!? :-\
Title: Re: Need help with significant figures
Post by: bamcanfly on September 08, 2009, 09:28:00 AM: i thought you were asking me how many sig. fig. are in 0.034 but I was unsure so i added a question to my answer of 3
Title: Re: Need help with significant figures
Post by: kor on September 08, 2009, 09:41:29 AM: For x significant figures
you need to write X number of digit
if the first digit is 0 don't count it
Title: Re: Need help with significant figures
Post by: Fridushka on September 08, 2009, 09:42:32 AM: I asked you other questions too..plz read the 2 posts, the 2nd and the 3rd
Well there are only 2, the 3 and 4 are the sig fig..while the zeros, before the decimal and after the decimal when it's writen at first the decide the position of the sig fig..
well plz try the others too so let me see your resluts and correct it together...
Good Luck :)