Significant Figures of 225.0 & Molar Volume at STP

In summary, the conversation discusses the number of significant figures in 225.0 and whether the trailing zeros should be considered. The solution suggests that the answer is 3 significant figures, while the person believes it should be 4. It is suggested to discuss with the instructor for clarification. Additionally, the conversation mentions the molar volume at STP and how it can be calculated with infinite accuracy due to all the numbers in the equation having an infinite number of significant digits.
  • #1
i_love_science
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What are the number of significant figures of 225.0? I think it is 4, but the solution says it's 3.

Also, is the significant figures of molar volume at STP (22.7 L/mol) considered? Thanks.
 
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  • #2
A super-duper quick Google (which doesn't count here) agrees with my understanding:
  • Trailing zeros to the right of the decimal ARE significant. ...
  • Trailing zeros in a whole number with the decimal shown ARE significant.
That suggests you are right. I'd take it up with your instructor.
 
  • #3
225.0 has four significant figures. Why did you include the zero in your answer? Did you round it from something like, 225.0173946289?
It sounds like it was part of a calculation and unless we see that calculation, we can’t tell you what is correct!
 
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  • #4
Molar volume of gas at STP can be calculated from the ideal gas equation. As of today all numbers in that equation - including R, ideal gas constant - are defined, that is, they have infinite number of significant digits (you can put as many zeros at the end as you need). That means it is possible to calculate molar volume with infinite accuracy.

It wasn't always this way, R used to be a measured quantity, with known experimental error.
 

1. What are significant figures and why are they important?

Significant figures are the digits in a numerical value that are considered to be reliable and accurate. They are important because they convey the precision and reliability of a measurement or calculation. In scientific calculations, it is important to use the correct number of significant figures to ensure accuracy and avoid misleading results.

2. How do you determine the number of significant figures in a measurement?

The rules for determining significant figures are as follows:

  • All non-zero digits are significant.
  • Any zeros between non-zero digits are significant.
  • Trailing zeros to the right of a decimal point are significant.
  • Leading zeros to the left of a decimal point are not significant.
  • Trailing zeros in a whole number with no decimal point may or may not be significant, depending on the context.

For example, in the measurement 225.0, there are four significant figures because all digits are non-zero and there is a decimal point present. In the measurement 0.0054, there are two significant figures because the zeros are trailing and there is a decimal point present.

3. What is the significance of using the correct number of significant figures in scientific calculations?

Using the correct number of significant figures in scientific calculations is important because it ensures the accuracy and precision of the results. If too few significant figures are used, the result may be rounded off and appear more precise than it actually is. On the other hand, if too many significant figures are used, it may give the false impression of accuracy and can lead to errors in subsequent calculations.

4. What is the molar volume at STP and how is it calculated?

The molar volume at STP (standard temperature and pressure) is the volume occupied by one mole of a gas at a temperature of 0°C (273.15 K) and a pressure of 1 atmosphere (101.325 kPa). It is calculated using the ideal gas law, which states that the volume of a gas is directly proportional to the number of moles present, and inversely proportional to the temperature and pressure. The equation for calculating molar volume at STP is V = (22.4 L/mol) x (T/273.15 K) x (P/1 atm), where T is the temperature in Kelvin and P is the pressure in atmospheres.

5. How do significant figures affect the calculation of molar volume at STP?

Significant figures play an important role in the calculation of molar volume at STP. The final answer should have the same number of significant figures as the value with the fewest significant figures used in the calculation. For example, if the temperature is given as 273.0 K with four significant figures, the final answer for molar volume should also have four significant figures. This ensures that the final result is not more precise than the given values and maintains the accuracy of the calculation.

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