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3 years ago

Calculate the mass percent of phosphorus in a strand of DNA that consists of equal amounts of each of the four N-bases.

Chemistry

1 answer:

Murljashka [212]3 years ago

7 0

Answer:

8.62%

Explanation:

The DNA is composed of the grouping of the nucleotides, which are composed of one phosphate group (PO₄⁻²), one molecule of sugar ( deoxyribose), and one N-base, which can be adenine, guanine, cytosine, and thymine.

Let's assume as a calculus basis, 1 mol of the compound, and, because it has the same amount of each N-base, 1 molecule of each N-base nucleotide.

The molar mass of phosphate is 95 g/mol, the molar of the deoxyribose is 134 g/mol, the molar mass of adenine is 135 g/mol, of guanine, is 151 g/mol, of cytosine is 111 g/mol, and of thymine is 126 g/mol.

So, the molar masses of the nucleotide of each N-base are:

Adenine: 95 + 134 + 135 = 364 g/mol

Guanine: 95 + 134 + 151 = 380 g/mol

Cytosine: 95 + 134 + 111 = 340 g/mol

Thymine: 95+ 134 + 126 = 355 g/mol

Thus, the mol with one of each of these N-bases has mass 1439 g (364 + 380 + 340 + 355). The molar mass of phosphorus is 31 g/mol, so 1 mol has 31 g. Each nucleotide has one phosphorus, so the total mass of phosphorus is 124 g (4*31).

The percent of phosphorus is then:

(124/1439)*100% = 8.62%

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How much heat is required to change 56.0 g of ice (H2O) at 263 K to vapor (steam) at 400 K?

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Heat required = 173 kJ

<h3>Further explanation</h3>

Given

56.0 g of ice

Temperatur at 263 K(-10 C) to 400 K(127 C)

Required

Heat needed

Solution

1. raise the temperature(-10 C to 0 C)⇒c ice=2.09 J/g C

$\tt Q=56\times 2.09\times (0-(-10)=1170.4~J$

2. phase change (ice to water)⇒Heat of fusion water=334 J/g

$\tt Q=56\times 334=18704~J$

3. raise the temperature(0 C to 100 C)⇒c water= 4.18 J/g C

$\tt Q=56\times 4.18\times (100-0)=23408~J$

4. phase change(water to vapor)⇒heat of vaporization water=2260 J/g

$\tt Q=56\times 2260=126560~J$

5. raise the temperature(100 C to 127 C)⇒c vapor=2.09 J/g C

$\tt Q=56\times 2.09\times (127-100)=3160.08~J$

Total heat :

1170.4+18704+23408+126560+3160.08=173,002.48 J=173 kJ

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What is the boiling point of an aqueous solution that has a vapor pressure of 23.0 torr at 25 ∘C? (P∘H2O=23.78 torr; Kb= 0.512 ∘

UNO [17]

Answer:

Boiling point of the solution is 100.964°C

Explanation:

In this problem, first, you must use Raoult's law to calculate molality of the solution. When you find the molality you can obtain the boiling point elevation because of the effect of the solute in the solution (Colligative properties).

Using Raoult's law:

Psol = Xwater × P°water.

As vapour pressure of the solution is 23.0torr and for the pure water is 23.78torr:

23.0torr= Xwater × 23.78torr.

0.9672 = Xwater.

The mole fraction of water is:

$0.9672 = \frac{X_{H_2O}}{X_{H_2O}+X_{solute}}$

Also,

$1 = X_{H_2O}+X_{solute}$

You can assume moles of water are 0.9672 and moles of solute are 1- 0.9672 = 0.0328 moles

Molality is defined as the ratio between moles of solute (0.0328moles) and kg of solvent. kg of solvent are:

$09672mol *\frac{18.01g}{1mol}* \frac{1kg}{1000g} = 0.01742kg$

Molality of the solution is:

0.0328mol Solute / 0.01742kg = 1.883m

Boiling point elevation formula is:

ΔT = Kb×m×i

<em>Where ΔT is how many °C increase the boiling point regard to pure solvent, Kb is a constant (0.512°C/m for water), m molality (1.883m) and i is Van't Hoff factor (Assuming a i=1).</em>

Replacing:

ΔT = 0.512°C/m×1.882m×1

ΔT = 0.964°C

As the boiling point of water is 100°C,

<h3>Boiling point of the solution is 100.964°C</h3>

<em />

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D. Sometimes it is necessary to put forth new theories to explain experimental results,

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Creativity is important to science because sometimes, it is necessary to put forth new theories to explain experimental results.

Theories are explanation of scientific observations.

Most scientists are critical and creative thinkers.
They must be able to come up with a wide range of possible explanation to explain their findings.
The explanations must be scientific in nature and not fall out of the basic tenets of this way of thinking.
Therefore, scientists draw from their wealth of deductive reasoning to give explanations into an observed phenomenon.

learn more:

Purpose of conducting experiments brainly.com/question/5096428

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