I need help putting my answers in significant figures thanks

2 C8H18(g) + 25 O2(g)  16 CO2(g) + 18 H2O­(g) at STP

How many moles of O2 are needed to react with 60.0g of C8H18 (octane)?

mole of 02 = 60/114 = 53 mols

2 moles of octane =25 mols of 02

0.53/2 x 25= 6.625 mols

How many litres of CO2 are produced?

16 x 0.53mol/2mol = 4.24 moles

4.24mol x 22.4 L = 94.976 L of co2

One of the best 10 minute videos on significant figures I've seen is on YouTube. Go to => h t t p s : / / w w w . h t t p s : / / w w w . youtube.com/watch?v=GVRKRsegiCE

Also, remember the use of significant figures as well as other number adjusting concepts (averages, standard deviations, confidence intervals, etc.) are used primarily for expressing laboratory results in more realistic d imensions relative to the measuring instruments being used. Typically, the final answers are rounded - using the appropriate rules - to values relating to the instrument having the LEAST DEGREE OF ACCURACY in the experimental process. Please review the above video. It is only ~10 minutes long and will make a big difference in your understanding of sig. figs. If you need further assists afterwards, post again. Good Luck, Doc

thank you!

Also, on sig figs, for problems, rounding is should be related to 'DATA' given. That is, do not use conversion factors or universal constants. DATA reflects the instrumental & experimental measurements used in the data collection process.

For your problem posted, (a) ? moles O2 needed for 60-gms C8H18.

2C₈H₁₈ + 25O₂ => 16CO₂ + 18H₂O
60-g =>? moles O₂
(60-g/114-g∙molˉ¹) = 0.5263 mol C₈H₁₈ =>? moles O₂
*****************************
Using equation rxn ratios…
2-mole C₈H₁₈/0.5263-mole C₈H₁₈ = 25-mol O₂/X
X = (25/2) (0.5263-mol O₂) = 6.578947368-mol O₂ (calculator answer)

Since the data given (= 60-g C₈H₁₈) => 1 sig. fig. (counts right to left with no decimal in number, 1st non-zero digit starts count on sig. figs. => 1 sig. fig.)

Appropriate answer => moles of O₂ needed for 60-g C₈H₁₈ = 7-moles O₂.
See vid. :-)

To properly express your answers in significant figures, follow these steps:

1. Determine the number of significant figures in the given measurement or value.

- "60.0g" has three significant figures.

2. Perform the calculations as usual without considering significant figures.

- In the equation, 1 mole of C8H18 requires 25 moles of O2.

- Thus, \( \frac{60.0g \ C8H18}{114 \frac{g}{mol}} = 0.526 \ mol \ C8H18 \)

- Then, \( 0.526 \ mol \ C8H18 \times \frac{25 \ mol \ O2}{2 \ mol \ C8H18} = 6.575 \ mol \ O2 \)

- And, \( 16 \ mol \ CO2 \times \frac{0.526 \ mol \ O2}{2 \ mol \ C8H18} = 4.24 \ mol \ CO2 \)

3. Determine the final answer's significant figures based on the least number of significant figures in the given measurements or values used in the calculation.

- In this case, the least number of significant figures is 3 (from "60.0g").

4. Round the final answer to the least number of significant figures.

- Rounding the number 4.24 to three significant figures gives us 4.24 L of CO2.