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3 years ago

What do atomic-scale models show you that your observations of properties cannot?

1 answer:

4 0

The atomic number is the number of protons in the nucleus of an atom. The number of protons define the identity of an element.

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Calcular la cantidad de NaOH necesaria para preparar medio litro de disolución 2,5 N. (Dato: peso molecular del NaOH = 40 g/mol)

kolbaska11 [484]

Answer:

The amount of NaOH required to prepare a solution of 2.5N NaOH.

The molecular mass of NaOH is 40.0g/mol.

Explanation:

Since,

NaOH has only one replaceable -OH group.

So, its acidity is one.

Hence,

The molecular mass of NaOH =its equivalent mass

Normality formula can be written as: $Normality=\frac{mass of solute NaOH}{its equivalent mass} * \frac{1}{volume of solution in L} \\$

Substitute the given values in this formula to get the mass of NaOH required.

$2.5N=\frac{mass of NaOH}{40g/mol} *\frac{1}{1L} \\mass of NaOH=2.5N*40gmol\\ = 100.0g$

Hence, the mass of NaOH required to prepare 2.5N and 1L. solution is 100g

8 0

3 years ago

How is shielding effect related to atomic radius?

jolli1 [7]

Shielding effect being attendency of the inner electrons to repel the outermost electrons, an increase in shielding effect increases atomic radius and decrease reduces the atomic radius

7 0

3 years ago

Convert 6.35 grams of aluminum sulfate to moles

vampirchik [111]

Answer:

There are 0.0186 moles of formula units in 6.35 grams of aluminum sulfate $\rm Al_2(SO_4)_3$ .

Explanation:

What's the empirical formula of aluminum sulfate?

Sulfate is an anion with a charge of -2 per ion. When sulfate ions are bonded to metals, the compound is likely ionic.

Aluminum is a group III metal. Its ions tend to carry a charge of +3 per ion.

The empirical formula of an ionic compound shall balance the charge on ions with as few ions as possible.

The least common multiple of 2 and 3 is 6. That is:

Three sulfate ions $\rm {SO_4}^{2-}$ will give a charge of -6.
Two aluminum ions $\rm Al^{3+}$ will give a charge of +6.

Pairing three $\rm {SO_4}^{2-}$ ions with two $\rm Al^{3+}$ will balance the charge. Hence the empirical formula: $\rm Al_2(SO_4)_3$ .

What's the mass of one mole of aluminum sulfate? In other words, what's the formula mass of $\rm Al_2(SO_4)_3$ ?

Refer to a modern periodic table for relative atomic mass data:

Al: 26.982;
S: 32.06;
O: 15.999.

There are

two Al,
three S, and
twelve O

in one formula unit of $\rm Al_2(SO_4)_3$ .

Hence the formula mass of $\rm Al_2(SO_4)_3$ :

$\underbrace{2\times 26.982}_{\rm Al} + \underbrace{3\times 32.06}_{\rm S} + \underbrace{12\times 15.999}_{\rm O} = \rm 342.132\;g\cdot mol^{-1}$ .

How many moles of formula units in 6.35 grams of $\rm Al_2(SO_4)_3$ ?

$\displaystyle n = \frac{m}{M} = \rm \frac{6.35\;g}{342.132\;g\cdot mol^{-1}} = 0.0186\;mol$ .

8 0

3 years ago

Moved mostly by wind and sometimes water, these constructive land features can be found on the coast and also in the desert. The

lidiya [134]

The answer would be B) Dunes. I hope you have a wonderful day :)

8 0

4 years ago

Why do we use models to study atoms

yaroslaw [1]

The real thing is reaallly tiny, you won't be able to view it with a microscope. that's why models are used to study atoms.

6 0

4 years ago

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