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Questions tagged [significant-figures]

For questions regarding the digits of a number used to express it to a particular degree of accuracy.

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How to get a precise answer to a textbook precipitation problem?

This question concerns a textbook problem* on precipitation. Briefly, there are $2\cdot10^{-4}$ of Mn$^{2+}$ and Cu$^{2+}$ ions in a liter of solution with $0.003$ M HClO$_4$. This solution is then ...
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1answer
20 views

Significant Figures Calculations and Precise Instruments [closed]

I understand the rules for significant figures and how to read instruments, except for one thing. I was told that our digital scale is particularly precise to the 1,000ths decimal place. So in ...
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1answer
314 views

Significant figures in percent error calculation?

Consider a percent error calculation where the measured value has 1 significant figure (XmL), and the actual/true value has 3 significant figures (0.XXXmL). Typically I would think that the percent ...
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1answer
42 views

How do significant figures work on this computation?

This isn't a homework question although it may seem like one. We've never really discussed significant figures and it was just introduced to us when we were learning how to solve word problems ...
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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 ...
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3answers
147 views

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 ...
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1answer
40 views

Significant figures conflict [duplicate]

So I am asked to solve this question from Silberberg: Use Appendix C to calculate $[\mathrm{H_2S}]$, $[\mathrm{HS}^-]$, $[\mathrm{S^{2-}}]$, $[\mathrm{H_30}^+]$, $\mathrm{pH}$, $[\mathrm{OH}^-]$, $\...
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1answer
105 views

AP Chemistry: Sig Figs Question

This is the official answer of a problem on the AP Chemistry 2009B Exam: The answer has two sig figs, but I think it should have 4 sig figs. I was taught that your end answer should have as many sig ...
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2answers
423 views

How would I use significant figures to find the answer of these dimensional analysis questions? [closed]

In chemistry class, I have been given a set of dimensional analysis questions to answer. I'm not sure if the units factor into whether or not significant figures will need to be applied. I know that ...
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1answer
169 views

Am I Using the Correct Number of Significant Figures (Heat Problem)?

The question is: A patient arrives in the emergency room with a burn caused by steam. Calculate the heat, in kilocalories, that is released when $\pu{18.0 g}$ of steam at $\pu{100 °C}$ hits the ...
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0answers
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Is significant figure important for atomic radius calculations? [closed]

Is significant figure important for atomic radius calculations? Calculate the radius of a vanadium atom, given that V has BCC crystal structure, a density of $\pu{5.96 g/cm^3}$, and an atomic ...
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2answers
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Chemistry 101 - significant figures [closed]

So i had my first chemistry 101 exam and got 21/25 , but iam not sure about one question, it's about significant digits , can u guys check if my answer is true or false as shown in picture. Thanks
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955 views

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 ...
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1answer
178 views

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 ...
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1answer
838 views

Uncertainty of Atomic Mass [closed]

How should the uncertainty of the atomic masses of elements be quoted? E.g., Mg has an atomic mass of 24.31, what is that value's uncertainty?
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1answer
683 views

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 = ...
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1answer
81 views

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 ...
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3answers
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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.
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1answer
377 views

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 ...
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2answers
317 views

Ka relating to Dissociation of Weak acid and Water

I am studying $K_a$ currently and there is a passage in the book that doesn't appear to make sense. It states that from the equation $$\ce{HA <=> H+ + A-}$$ that $$K_a = \frac{[H^+][A^-]}{[...
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2answers
6k views

Percent error and significant figures?

For an elementary chemistry class percent error is calculated as: [actual-experimental]/actual x 100% edit:bracket represents absolute value So my question is if the experimental is close enough to ...
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2answers
40 views

How to solve a math expression with proper significant digits?

I've talked with my friend from chemistry about this question, and looked all over the internet for like hours now, and couldn't find anything that would help in my situation. The problem is this: $$...
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2answers
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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}}...
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2answers
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Significant Figures Calculations

I am confused regarding significant figures. Consider "Calculate the volume of 2.8 kg of liquid with density of 1.11 g/cm^3" Then, Volume = 2.8 kg * (cm^3 / 1.11 g) = 2522.522 (where 522 is recurring)...
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1answer
79 views

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 ...
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1answer
868 views

Rounding significant figures

Calculate how many grams of p-nitrophenol are required to prepare $250~\mathrm{mL}$ of a $11~\mathrm{mM}$ solution. (Answer to 3 significant figures.) I worked it out as $$\begin{align} \frac{250}{...
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2answers
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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 ...
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1answer
221 views

How to recognise the significant figures in given input values for the calculated output value?

If the transfer of $1~\mathrm{kJ}$ of energy to a quantity of water causes its temperature to rise $10~^\circ\mathrm{C}$, what is the mass of the water? I know how to do the math and everything but I'...
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1answer
22k views

How do I round a calculation involving both addition/subtraction and multiplication/division to the correct number of significant figures?

I'm just learning about significant figures (sig figs) in my chemistry class, and I'm confused about the rules. An example to my problem: if I had the following expression: $$\left ( \frac{2.378 - 1.2}...
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1answer
196 views

How to use signicant figures?

I am confused about significant figures. In a teaching video, the teacher showed this math: $$ 22.2 + 22.2 + 30.10 + 30.10 = 104.6$$ This is, of course, the actual answer, but in using significant ...
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1answer
19k views

Why x in equilibrium calculations can be “ignored”

You don't need to work out anything for me. I am just giving an example so you can explain something to me. For example: $$\ce{ClF3(g) <=> ClF(g) + F2(g)}\\ \ \ K_c=8.77\times10^{-14} \ \ @\ ...
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2answers
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Significant Figures Interpretation

Please correct me if I’m wrong, but I’ve read that the reason why we use significant figures is to avoid making the result of a calculation more accurate than the starting values prior to the ...