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Topic: new at this..simple operations  (Read 4009 times)

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anlb4

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new at this..simple operations
« on: September 01, 2004, 08:35:57 AM »
 ???This is my first chemistry course and I am taking algerbra at the same time...how do you figure out the answer for the following

11.01/0.088     I must express the result with the correct number if significant figures  
the answer is 1.3 x 10 to the 2   but i do not know how to get that  please help this is one i am stuck on

Offline jdurg

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Re:new at this..simple operations
« Reply #1 on: September 01, 2004, 10:18:40 AM »
Okay.  Knowing significant figures is a HUGE part of chemistry.  Significant figures define just how much precision the data can be reported in.  I'm not going to get really far into the Sig. Fig. explanation since I'm sure you have a textbook which can describe it in a less confusing manner than I can.  hehe.

So the first thing you need to do is determine how many significant figures each of the values you are using have.  For the first value, 11.01, you would have four significant figures since any digit that is not a 0 is significant, and any 0s surrounded by other digits is significant.  (Since the zero is surrounded by 1s, it is considered significant).  

For the second value, you only have two digits which aren't zeros, and the zeros which are present are simply placeholders.  (The zero after the decimal point is really not doing anything but holding a place in the number).  So your second value has two significant figures.  As a result, your answer can only have two significant figures in it since your "least precise" measurement has only two.  Your answer cannot have more significant figures than your least precise value.  (This should make sense because the answer can only be as precise as your least precise measurement).

So now you just need to do the simple division.  11.01/.088 = 125.1136363636...  You now need to round your answer so that it only has two significant figures.  This will give you 130 as an answer.  Now in chemistry, and most all sciences, the preferred method of reporting data is in scientific notation.  For this answer, the proper scientific notation is 1.3x102.  Scientific notation pretty much just means "take the value given, and move the decimal point however many spaces to the left or right denoted by the superscript."  In this case, the superscript is a +2, so you'd move the decimal point two places to the right on the initial number.  1.3 -> 130.  130 is the answer you came up with so the scientific notation you used was correct.  

Do you kind of understand it now?  Hopefully I didn't confuse you too much.   ;D
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anlb4

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Re:new at this..simple operations
« Reply #2 on: September 01, 2004, 03:11:51 PM »
Thank you..made it much clearer to understander, my professor seems to assume we know this already..I am sure I will be posting again!! :)

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