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Feliz [49]
2 years ago
7

Calculate the number of atoms in 2.5 moles of Si.

Chemistry
1 answer:
Ede4ka [16]2 years ago
7 0

Answer:

\boxed {\boxed {\sf About \ 1.5 * 10^{24} \ atoms \ Si}}

Explanation:

When converting from moles to atoms, we must use Avogadro's number. This number tells us there are 6.022 * 10²³ atoms in 1 mole. We can multiply this number by the number of moles.

First, we must set up Avogadro's number as a ratio.

\frac {6.022 \ * 10^{23} \ atoms \ Si }{1 \ mol \ Si}}

Next, multiply the number of moles by the ratio.

2.5 \ mol \ Si *\frac {6.022 \ * 10^{23} \ atoms \ Si }{1 \ mol \ Si}}

When we multiply, the moles of silicon will cancel.

2.5 * \frac {6.022 \ * 10^{23} \ atoms \ Si }{1}}

Since the denominator of the fraction is 1, we can cancel it out too.

2.5 *  {6.022 \ * 10^{23} \ atoms \ Si }

1.5055 * 10^{24} \ atoms \ Si

The original measurement (2.5 moles) has 2 significant figures (2 and 5). Therefore we must round to 2 sig figs. For this question, 2 sig figs is the tenth place.

The 0 in the hundredth place tells us to leave the 5 in the tenth place.

1.5 * 10^{24} \ atoms \ Si

There are about <u>1.5 * 10²⁴ atoms of silicon.</u>

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