For questions regarding the digits of a number used to express it to a particular degree of accuracy.
Questions tagged [significant-figures]
55 questions
8
votes
3 answers
Decimal places vs significant figures
I was given an online assignment problem today. The answer was to be given to 2 decimal places. The answer I gave was $$P_2=0.06$$
This to me seems like 2 decimal places. However the answer was incorrect. I then wrote $$P_2=0.064$$
It was correct. I…
Patrick Moloney
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5
votes
3 answers
What do final zeros to the right of decimal point indicate?
Final zeros to the right of the decimal point are considered significant. What do those zeros indicate and why are they significant? For example, in 2.000 there are four significant figures.
AksaK
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4
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1 answer
How to round significant figures correctly?
Calculate how many grams of p-nitrophenol are required to prepare $\pu{250 mL}$ of a $\pu{11 mM}$ solution. (Answer to 3 significant figures.)
I worked it out as
\begin{align}
\frac{250}{1000}\,\mathrm{L} \times (\pu{11E-3 M}) \times \pu{139.11…
Edward
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4
votes
3 answers
Significant Figures
I recently did my first chemistry lab where we had to find the average mass of our aluminum cylinder. We were required to weigh and record its mass 3 times using an electric balance which gave us a value up to the thousandths place. After recording…
George
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2
votes
1 answer
Use of significant figures in addition and subtraction
My book mentions:
The proper use of significant figures in addition and subtraction involves a comparison of only the absolute uncertainties of numbers. This means that only as many digits are retained to the right of the decimal point in the…
AksaK
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2
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2 answers
Significant figures in conversion factors?
Example: I have $\pu{64 cm^{3}}$ of milk. How much is that in gallons?
When I use the conversion factors $\frac{\pu{1 mL}}{\pu{1 cm^3}}$
$\frac{\pu{1L}}{\pu{1000 mL}}$ $\frac{\pu{1.0567 qt}}{\pu{1 L}}$ $\frac{\pu{1 gal}}{\pu{4 qt}}$.
I know the…
eromod
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vote
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How many significant digits are appropriate when one or more digits are eliminated (during subtraction)?
Say, for example, $50.0-49.6=0.4$. Does this result have $1$ significant figure, or $3$ (as in the data: $50.0$ and $49.6$)?
Had it been $50.0-4.6$, it is understood that the answer is $45.4$, by the rules of significant figures. How do I apply…
digikar
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1
vote
1 answer
When expressing a quantity, do the non-significant figures determine whether you round up the last significant figure?
I had thought that the non significant figures determined whether the least significant figure was to be rounded up. For example, given the number $9.1145$, if the number is to be expressed as three significant figures, then, I had thought that, it…
Hal
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1
vote
2 answers
How determine the number of significant figures of a feet/inch system?
How many significant figures are there in $5~\mathrm{ft}\ 10~\mathrm{in}$.
I know that $5~\mathrm{ft}\ 10~\mathrm{in}= 5.8\bar{3}~\mathrm{ft}=70~\mathrm{in}$, so I am not sure exactly how much significant digits are in this number.
Ahmed S. Attaalla
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vote
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What is a reliable way of writing significant figures in multi-step problems?
I understand the sig fig rules that pertain to addition and multiplication problems, however, in multi-step problems, I have not been able to find a systematic approach to getting the right amount. Everybody who I have asked just said "it's tricky…
Albert Goldman
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vote
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Why should you round to proper significant figures after you complete a calculation rather than while doing the calculation?
In class, my teacher mentioned that you should complete a calculation without considering significant figures and then at the very end, round to the proper number of significant figures. Why couldn't we just round the numbers after each step of the…
user198511
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0
votes
1 answer
Does the multiplication and division significant figures rule apply to unit conversions as well?
My chemistry teacher told our class that answers to calculations that involve multiplication and division should be given to same number of significant figures as the factor, dividend or divisor with the lowest no. of sig.figs.
For example, to…
Tom Brooks
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0
votes
1 answer
Converting units and sig figs (finding molarity)?
This may seem very basic, but I'm a little confused.
"What is the molarity of a solution 500 mL of which contains 0.500 moles of HCl?"
Being that 500 has one significant figure, would it be 500 mL = 0.5 L as opposed to 500 mL = 0.500 L? In which…
Hello
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0
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2 answers
Why do significant figure rules contradict each other?
So I came across a problem in my chemistry textbook that brought up another question. The problem had to do with calculating the mass% composition of chlorine in a certain molecule.
So to go about solving this, you could calculate the mass in grams…
Cotton Headed Ninnymuggins
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0
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A sample must not contain more than 2% contaminants to be pure. Are there instances where 2.12% is ok?
I do not have any background in chemistry, I am asking this on behalf of someone else, twice translated, so I really hope it makes sense.
"A maximum of 2%" seems quite a clear specification, but since practice involves rounding of measurements and…
355durch113
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