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3 years ago

Select all that apply. Which of the following measurements have 3 significant figures? 0.0882 m 0.8820 m 8,820 m 882.0 m

Chemistry

2 answers:

mixer [17]3 years ago

4 0

Answer:

0.0882

8,820

Explanation:

0.0882 is one . The significant figures are 882. We ignore the leading zeroes.

0.8820 has 4 significant figures.

8.820 also has 3 significant figures (we do not count the trailing zero).

882.0 has 4 significant figures.

MatroZZZ [7]3 years ago

3 0

8820 and 0.0882 have three sig figs

When a number has zeros in it I struggled a lot to determine if it what a sig fig or not. This is how I remember it:

If a zero is a sandwich between normal numbers it IS a sig fig

Zero's after the decimal ARE sig figs

***IMPORTANT! There is an exception to this one which I'll talk about next :)

Leading zeros (I believe that is what they are called) are NOT sig figs. This would be like the zeros in the following numbers:

0.2

0.03

0.000000000000000000006

If there are zeros after normal numbers and there is NO DECIMAL it is NOT a sig fig. This would be like the zeros in the following numbers:

630

3, 000

536, 329,600,000

Take a look at the other numbers:

0.8820 <<<This has 4 sig. figs.

882.0 <<<This has 4 sig. figs.

***Remember that if there is a pure decimal the zero in front of the decimal is NOT a sig fig and just a place holder. It isn't necessary and can always be taken away

Hope this made sense and helped!!!

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Explanation:

Given that:

The flow rate Q = 0.3 m³/s

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reaction rate K = 5.09 hr⁻¹

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$time (t) = \dfrac{V}{Q}$

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$0.185 = \dfrac{1}{5.09} \Big ( \dfrac{200}{C_e}- 1 \Big)$

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$\dfrac{200}{C_e} = 1.942$

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Thus; the concentration of species in the reactant = 102.98 mg/l

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$t _{PFR} = \dfrac{1}{k} \Big [ In ( \dfrac{C_o}{C_e}) \Big ]$

$\dfrac{V_{PFR}}{Q_{PFR}} = \dfrac{1}{k} \Big [ In ( \dfrac{C_o}{C_e}) \Big ]$

$\dfrac{V_{PFR}}{Q_{PFR}} = \dfrac{1}{5.09} \Big [ In ( \dfrac{200}{102.96}) \Big ]$

$\dfrac{V_{PFR}}{Q_{PFR}} =0.196 \Big [ In ( 1.942) \Big ]$

$\dfrac{V_{PFR}}{Q_{PFR}} =0.196(0.663)$

$\dfrac{V_{PFR}}{0.3 hrs} =0.196(0.663)$

$\dfrac{V_{PFR}}{0.3*3600 sec} =0.196(0.663)$

$V_{PFR} =0.196(0.663)*0.3*3600$

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The volume of the PFR is ≅ 140 m³

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Whitepunk [10]

From the periodic table:
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molar mass of CH2Cl2 = 12 + 2(1) + 2(35.5) = 85 grams

number of moles = mass / molar mass
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One mole of CH2Cl2 contains two moles of Cl and each chlorine mole has Avogadro's number of atoms in it.
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number of atoms = 0.777 * 2 * 6.022 * 10^23 = 9.358 * 10^23 atoms

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