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Katyanochek1 [597]
3 years ago
5

What is the mole fraction of solute and the molal concentration for an aqueous solution that is 20.0% NaOH by mass?

Chemistry
1 answer:
never [62]3 years ago
8 0
Let's assume we have 100 grams of this solution, and therefore 20.0 grams of NaOH, and 80.0 grams of water.

NaOH has a molar mass of 40.00 grams/mole, so we can convert NaOH to moles: (20.0 grams of NaOH) * (1 mole NaOH/40.00 grams NaOH) = 0.500 moles NaOH.

Next, we have a molar mass of water of 18.02 g/mol, so we can convert water to moles:

80.0 grams H2O * (1 mole H2O/18.02 grams) = 4.44 moles H2O
The mole fraction of NaOH is the moles of NaOH over the total moles of all parts of the solution. Therefore:

(0.500 moles NaOH)/(0.500 moles + 4.44 moles) = 0.101
0.101 = mole fraction of solute

The molal concentration is defined as the number of moles of solute over the number of kilograms of solvent (water).
We have 0.500 moles of NaOH, and 0.0800 kg of water, so it becomes:
(0.500 moles NaOH)/(0.0800 kg H2O solvent) = 6.25 molal solution
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Goryan [66]

Answer:

C. Trp D. Phe E. Tyr

Explanation:

The concentration of a protein has a direct relation with absorbance of the protein in a UV spectrophotometer. The formula which relates concentration with absorbance is described as under:

                A = ∈ x c x l

where, A = Absorbance

            ∈ = Molar extinction co-efficient

            c  = Concentration of absorbing species i.e. protein

             l  = Path length of light

       

Tryptophan (Trp), phenylalanine (Phe ) and tyrosine (Tyr) are three aromatic amino acids which are used to measure protein concentration by UV. It is mainly because of tryptophan (Trp), protein absorbs at 280 nm which gives us an idea of protein concentration during UV spectroscopy.

The table depicting the wavelength at which these amino acids absorb and their respective molar extinction coefficient is as under:

Amino acid                Wavelength            Molar extinction co-efficient (∈)

Tryptophan                     282 nm                        5690

Tyrosine                          274 nm                        1280

Phenylalanine                 257 nm                        570

In view of table above, we can easily see that Molar extinction co-efficient (∈) of Tryptophan is highest amongst all these 3 amino acids that is why it dominates while measuring concentration.

7 0
3 years ago
How are the particles of butterfat made smaller so that the mixture is homogenized?
nalin [4]

Explanation:

A heterogeneous mixture has particles that are not uniformly distributed, but a homogeneous mixture has particles that are uniformly distributed.

4 0
3 years ago
Approximately how many formula units of NaCl are in 116.88g of table salt (NaCl), knowing that the molar mass of NaCl is 58.44g/
elena-14-01-66 [18.8K]

Answer:

116.88g of table salt (NaCl) contains two formula units

Explanation:

Now,

We know that 1 formula unit of sodium chloride has a molar mass of 58.44g/mol

Hence;

Mass of 1 formula unit = 58.44g

Mass of x formula units = 116.88g

x = 116.88g * 1 formula unit/58.44g

x = 2 formula units

Therefore;

116.88g of table salt (NaCl) contains two formula units

5 0
3 years ago
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The element copper has 29 protons. What is the atomic number of copper?
stiks02 [169]
The atomic number of copper is 29.

Hope this helps and if it does, don't be afraid to rate my answer as well as maybe give it a "Thanks"? (Or even better a "Brainliest"). And if it’s not correct, I am sorry for wasting your time, and good luck finding the correct answer :)


8 0
2 years ago
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Pls help 2-3 tyvm ‏‏‎ ‎ ‏‏‎ ‎ ‏‏‎ ‎ ‏‏‎ ‎ ‏‏‎ ‎ ‏‏‎ ‎ ‏‏‎ ‎ ‏‏‎ ‎ ‏‏‎ ‎ ‏‏‎ ‎ ‏‏‎ ‎ ‏‏‎ ‎
Triss [41]

Answer:

I could I guess?

But like only 1 lol

Explanation:

6 0
3 years ago
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