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icang [17]
3 years ago
8

A 5.21 mass % aqueous solution of urea (CO(NH2)2) has a density of 1.15 g/mL. Calculate the molarity of the solution. Give your

answer to 2 decimal places.
Chemistry
2 answers:
Alex777 [14]3 years ago
4 0

Answer:

Molarity is 0.99 M

Explanation:

5.21% by mass, is a sort of concentration which shows the mass of solute in 100 g of solution.

Molarity is a sort of concentration that indicates the moles of solute in 1 L of solution (mol/L)

Let's find out the volume of solution by density.

Solution density = Solution mass / Solution volume

1.15 g/mL = 100 g / Solution volume

Solution volume = 100 g / 1.15 g/mL → 86.9 mL

We must have the volume of solution in L, so let's convert it.

86.9 mL / 1000 = 0.0869 L

Now, we have to determine the moles of solute (urea)

5.21 g . 1 mol / 60 g = 0.0868 moles

Mol/L = Molarity → 0.0868 moles / 0.0869L  = 0.99 M

aleksley [76]3 years ago
3 0

Answer:

\large \boxed{\text{1.00 mol/L}}

Explanation:

Molar concentration = moles/litres

So, we need both the number of moles and the volume.

1. Volume

Assume a volume of 1 L.

That takes care of that.

2. Moles of urea

(a) Mass of solution

\text{ Mass of solution} = \text{1000 mL} \times \dfrac{\text{1.15 g solution}}{\text{1 mL}} = \text{1150 g solution}

(b) Mass of urea

\text{Mass of urea} = \text{1150 g solution}\times \dfrac{\text{5.21 g urea}}{\text{100 g solution}} = \text{59.92 g urea}

(c) Moles of urea

\text{Moles of urea} = \text{59.92 g urea} \times \dfrac{\text{1 mol urea}}{\text{60.06 g urea}} = \text{1.00 mol urea}

3. Molar concentration

\text{Molar concentration} = \ \dfrac{\text{1.00 mol}}{\text{1 L}} = \textbf{1.00 mol/L}\\\text{The molar concentration of the urea is $\large \boxed{\textbf{1.00 mol/L}}$}

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All solutions<br>are mixtures; but<br>all mixtures are<br>not solutions.<br>why?​
aleksklad [387]

All solutions are mixtures of two or more substances, but unless the mixture has a homogeneous distribution of solutes in the solvent, then the mixture is not a solution. Therefore, all mixtures are not solutions.

5 0
2 years ago
Convert the composition of the following alloy from atom percent to weight percent (a) 44.9 at% of silver, (b) 46.3 at% of gold,
vesna_86 [32]

Answer:

Mass percentage of gold : 33.35%

Mass percentage of silver: 62.80%

Mass percentage of copper : 3.85%

Explanation:

N=n\times N_A

Where : N = Number of atoms

n = moles

N_A=6.022\times 10^{23} = Avogadro number

Let the total atoms present in the alloy be 100.

Atom percentage of silver = 44.9%

Atoms of of silver = 44.9% of 100 atoms = 44.9

Atomic weight of silver = 107.87 g/mol

Mass of 44.9 silver atoms = 107.87 g/mol ×  44.9 = 4,843.363 g/mol

Atom percentage of gold= 46.3%

Atoms of of gold = 46.3% of 100 atoms = 46.3

Atomic weight of gold = 196.97 g/mol

Mass of 44.9 gold atoms = 196.97 g/mol × 46.3 = 9,119.711 g/mol

Atom percentage of copper = 8.8 %

Atoms of of copper = 8.8% of 100 atoms = 8.8

Atomic weight of copper = 63.55 g/mol

Mass of 44.9 copper atoms = 63.55 g/mol ×  8.8 = 559.24 g/mol

Total mass of an alloy :4,843.363 g/mol + 9,119.711 g/mol +  559.24 g/mol

Mass percentage of gold :

\frac{4,843.363 g/mol}{4,843.363 g/mol + 9,119.711 g/mol +  559.24 g/mol}\times 100=33.35 \%

Mass percentage of silver:

\frac{9,119.711 g/mol}{4,843.363 g/mol + 9,119.711 g/mol +  559.24 g/mol}\times 100=62.80\%

Mass percentage of copper :

\frac{559.24 g/mol}{4,843.363 g/mol + 9,119.711 g/mol +  559.24 g/mol}\times 100=3.85\%

7 0
3 years ago
What’s the distance from the nucleus of an atom to its theoretical outer edge of electron orbits
ollegr [7]

Answer:

The range of atoms = (30-300 pm) depending upon the element

Explanation:

The Atomic radii of the atom is the distance from the center of the circle to the outermost orbital.

The center of the circle is the nucleus and the radii is the outermost boundary.

The actual size of the atom is decided on the basis of the Zeff . Also known as <em>effective nuclear charge.</em>

<em>Zeff: It is the net positive charge felt by the outermost electron by the nucleus.</em>

<em>The value of Zeff depends upon the shielding constant. More the shielding less will be the Zeff . Hence the size of the atom increases.</em>

Due to shielding the outermost electrons feel less pull of nucleus.

<em>The greater the Zeff , the smaller the radius of the atom.</em>

The formula used to calculate the atomic mass is :

r_{n}=\frac{52.9n^{2}}{Z}pm

Here "pm"= picometers

1 pm = 10^{-12}m

<u>The size of the smallest atom H-atom = 120 pm</u>

<u>The range of atoms = (30-300 pm)</u>

4 0
3 years ago
4. Are all prokaryotes bad?<br> Provide an example to support<br> your answer.
Rina8888 [55]

Answer:

Although they receive a bad rap from the media and pharmaceuticals, the majority of prokaryotes are either harmless or actually help eukaryotes, such as animals and plants, to survive and only a small number of species are responsible for serious illnesses.

Explanation:

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2 years ago
How many valence electrons does Carbonic Acid contain?
geniusboy [140]
4 carbon electrons. Hope this helps have a nice day
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