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denis-greek [22]
3 years ago
14

Aluminum oxide (Al2O3) occurs in nature as a mineral called corundum, which is noted for its hardness and resis- tance to attack

by acids. Its density is 3.97 g cm23. Calculate the number of atoms of aluminum in 15.0 cm3 corundum.
Chemistry
1 answer:
Neko [114]3 years ago
5 0

Answer:

7.03×10²³ atoms of Al

Explanation:

Corundum density = 3.97g/cm³

Corundum = Al₂O₃. Then, you have 2 moles of Al and 3 moles of O in 1 mol of the compound.

Let's determine the mass of corundum, by density

Corundum density = Corundum mass / Corundum volume

3.97 g/cm³ = Corundum mass / 15cm³

3.97 g/cm³ . 15cm³ = Corundum mass →59.55 g

Now, let's find out how many moles are in that mass of corundum

1 mol of Al₂O₃ weighs 101.96 g/mol

Then, 101.96 grams of oxide have 2 moles of Al

59.55 g of oxide, will have (59.55  .2)/101.96 = 1.17 moles

Now, we can know the quantity of atoms, by this rule of three

1 mol has NA atoms (6.02×10²³)

1.17 moles will have (1.17  . NA) = 7.03×10²³ atoms of Al

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Answer:

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Explanation:

\lambda =\frac{0.693}{t_{\frac{1}{2}}}

A=A_o\times e^{-\lambda t}

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3 years ago
A chemist has 3.55x1022 molecules of nitrogen monoxide. How
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Answer:

<h2>0.059 moles</h2>

Explanation:

To find the number of moles in a substance given it's number of entities we use the formula

n =  \frac{N}{L} \\

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From the question we have

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<h3>0.059 moles</h3>

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