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### Topic: WebAssign homework DUE MONDAY. NEEP HELP PLEASE  (Read 3013 times)

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#### JQKingsley

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##### WebAssign homework DUE MONDAY. NEEP HELP PLEASE
« on: June 08, 2012, 12:50:11 AM »
So, I just started taking a basic chem class but the problem is I haven't taken one since Junior year of high school. Soooo, I need help with a few problems that I'm pretty sure I'm just confused about the directions or how to start them.

First section,
Use appropriate prefixes to write the following measurements without the use of exponents.
(a). 1.1 x 10^-10 L
answer needs to be _______nL
So do I just take the 1.1 Liters and convert to nanoliters? Or do I convert the 1.1x10^-10L to decimal form and then go from there to nanoliters? And if I do, how do I do it?
Very simple, but I just don't understand.

Second section,
Carry out the following operations, and express the answer with the appropriate number of significant figures.
(a). 320.69 - (3104.9/3.3)
I got 620.2 but apparently that is incorrect.
I know that with adding and subtracting you have the sig figs of the number with the smallest sig figs. With multiplying and dividing, I know you take the amount of sig figs with the least as well. So in this case, would I have 2 sig figs? Or sig figs and 1 decimal place?
Thank you!

#### discodermolide

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##### Re: WebAssign homework DUE MONDAY. NEEP HELP PLEASE
« Reply #1 on: June 08, 2012, 12:55:49 AM »
So, I just started taking a basic chem class but the problem is I haven't taken one since Junior year of high school. Soooo, I need help with a few problems that I'm pretty sure I'm just confused about the directions or how to start them.

First section,
Use appropriate prefixes to write the following measurements without the use of exponents.
(a). 1.1 x 10^-10 L
answer needs to be _______nL
So do I just take the 1.1 Liters and convert to nanoliters? Or do I convert the 1.1x10^-10L to decimal form and then go from there to nanoliters? And if I do, how do I do it?
Very simple, but I just don't understand.

Second section,
Carry out the following operations, and express the answer with the appropriate number of significant figures.
(a). 320.69 - (3104.9/3.3)
I got 620.2 but apparently that is incorrect.
I know that with adding and subtracting you have the sig figs of the number with the smallest sig figs. With multiplying and dividing, I know you take the amount of sig figs with the least as well. So in this case, would I have 2 sig figs? Or sig figs and 1 decimal place?
Thank you!

1nL is 1x10-9 liters. So take it from there!
Work out the bit in brackets first.
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#### JQKingsley

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##### Re: WebAssign homework DUE MONDAY. NEEP HELP PLEASE
« Reply #2 on: June 08, 2012, 01:00:54 AM »
No, I know that. But I literally don't understand how to work it out from there . I'm just confused on the whole question

#### discodermolide

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##### Re: WebAssign homework DUE MONDAY. NEEP HELP PLEASE
« Reply #3 on: June 08, 2012, 02:28:40 AM »
No, I know that. But I literally don't understand how to work it out from there . I'm just confused on the whole question

1x10-10L = 11x10-9 L, if 1nL =1x10-9L then you have 11nL!

The bit in brackets works out to 940.88
thus 320.69 - 940.88 = -620.19
Development Chemists do it on Scale, Research Chemists just do it!
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#### Shirro

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##### Re: WebAssign homework DUE MONDAY. NEEP HELP PLEASE
« Reply #4 on: June 08, 2012, 05:01:15 AM »
No, I know that. But I literally don't understand how to work it out from there . I'm just confused on the whole question

1x10-10L = 11x10-9 L, if 1nL =1x10-9L then you have 11nL!

The bit in brackets works out to 940.88
thus 320.69 - 940.88 = -620.19

1x10^-10 L is not 11x10^-9 L. It's other way around:
1x10^-10 L = 0.1x10^-9
and
1x10^-10 L = 0.1 nL