E1 Sig Figs

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Joanne Kang 3I
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Joined: Thu Jul 25, 2019 12:17 am

E1 Sig Figs

Postby Joanne Kang 3I » Tue Oct 01, 2019 9:43 pm

The question: The field of nanotechnology offers some intriguing possibilities, such as the creation of fibers one atom wide. Suppose you were able to string together 1.00 mol Ag atoms, each of radius 144 pm, into one of these fibers by encapsulating them in carbon nanotubes (see Chapter 7). How long would the
fiber extend?

So the answer to this problem is 1.73 x 10^14 m. But if we were to keep sig figs consistent, wouldn't the answer be 2 x 10^14m?

Ryan Narisma 4G
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Joined: Fri Aug 30, 2019 12:18 am

Re: E1 Sig Figs

Postby Ryan Narisma 4G » Tue Oct 01, 2019 9:57 pm

Hi Joanne Kang 3I! The quantity given is 1.00 mol Ag atoms. Remember that if there is a decimal point, you must count the significant figures from Left to Right. Once you start counting significant figures you must include any zeros after the decimal point as a significant figure. So for this problem the number of significant figures of the 1.00 mol of Ag atoms is three (3). Another example would be if you had 1.0005 mol of Au (gold) atoms. How many significant figures do you have now? Because there is a decimal point you would start counting from left to right. So, starting with 1, count all the subsequent figures until you reach 5. There are five (5) significant figures, correct? Now let's say you had 0.00104 grams of C (carbon). How many sig figs are there? Since there is a decimal point you would start from left to right and count, however the zeros in front of the number "1" don't count. So, you would start with 1 and then count any following numbers after 1 for a total of 3 significant figures. I hope this helps!

Annie Chantasirivisal_4G
Posts: 114
Joined: Wed Sep 18, 2019 12:21 am

Re: E1 Sig Figs

Postby Annie Chantasirivisal_4G » Tue Oct 01, 2019 9:58 pm

1.00 has 3 sig figs, so it would still be 1.73 x 10^14.

Numbers after a decimal usually still count as part of the significant figures, even if it's the number 0, so if the number was 1.000000000 there would be 10 sigfigs.
320. would be 3 sigfigs.

However, if there was no decimal and the 0 was just a trailing zero, such as 320, there would only be 2 sigfigs.

Megan Ngai- 3B
Posts: 50
Joined: Fri Aug 09, 2019 12:17 am

Re: E1 Sig Figs

Postby Megan Ngai- 3B » Tue Oct 01, 2019 10:54 pm

When trying to figure out sig figs, you should always look at the original question to figure out how many sig figs will be in your answer. In your example, there were the numbers 1.00 mol Ag atoms and the number 144 pm. Both of those numbers have 3 sig figs. The answer would not be 2 x 10^14 because any numbers after the decimal point of 1.00 still count as sig figs (in this case 3). If there was no decimal and was 300000g, it would be 1 sig fig.

LBacker_2E
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Joined: Wed Sep 18, 2019 12:21 am
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Re: E1 Sig Figs

Postby LBacker_2E » Tue Oct 01, 2019 11:12 pm

When there are 0's without a decimal point, such as the number 200, they do not count toward the sig figs- this number has 1 sig fig. But if the 0's are after the decimal point, such as the number 2.00, they do count toward the sig figs- this number has 3 sig figs. Finally if there are 0's before a decimal point, such as the number 200., they do count ward the sig figs- this number has 3 sig figs as well.


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