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3 years ago

What mass of mgf2 is contained in 80.85 g of a 22.4% by mass solution of mgf2 in water?

2 answers:

4 0

Formula: % by mass = (mass of solute / mass of solution] *100

Data:

mass of solution = 80.85 g

% by mass = 22.4%

Unknown = mass of solute

Solution

% by mass = (mass of solute / mass of solution] *100 = >

mass of solute = % by mass * mass of solution / 100

mass of solute = 22.4 * 80.85 / 100 = 18.11 g

Answer: 18.11 g

atroni [7]3 years ago

4 0

Answer : The mass of $MgF_2$ contained is, 18.1104 grams

Solution : Given,

Given mass of solution = 80.85 g

22.4% by mass solution of $MgF_2$ means that 22.4 grams of $MgF_2$ present in 100 gram of solution.

As, 100 grams of solution contains 22.4 grams of $MgF_2$

So, 80.85 grams of solution contains $\frac{22.4}{100}\times 80.85=18.1104$ grams of $MgF_2$

Therefore, the mass of $MgF_2$ contained is, 18.1104 grams

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Which statement describes a change that occurs during a chemical reaction? A. Atoms in the original substances are changed into

trapecia [35]

Answer:

B. Atoms in the original substances are arranged in a different way to make new substances.

Explanation:

The best statement that describes a change that occurs in a chemical reaction is that atoms in the original substances are arranged in a different way to make new substances.

Chemical reactions obey the law of conservation of matter.
The law postulates that "matter is neither created nor destroyed in a chemical reaction but they are simply rearranged".
Therefore, atoms of compounds forms new bonds by rearranging to give a new product.

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2 years ago

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A mysterious white powder could be powdered sugar (C12H22O11), cocaine (C17H21NO4), codeine (C18H21NO3), norfenefrine (C8H11NO2)

rodikova [14]

Norfenefrine (C₈H₁₁NO₂).

<h3>Further explanation</h3>

We will solve a case related to one of the colligative properties, namely freezing point depression.

The freezing point of the solution is the temperature at which the solution begins to freeze. The difference between the freezing point of the solvent and the freezing point of the solution is called freezing point depression.

$\boxed{ \ \Delta T_f = T_f(solvent) - T_f(solution) \ } \rightarrow \boxed{ \ \Delta T_f = K_f \times molality \ }$

<u>Given:</u>

A mysterious white powder could be,

powdered sugar (C₁₂H₂₂O₁₁) with a molar mass of 342.30 g/moles,
cocaine (C₁₇H₂₁NO₄) with a molar mass of 303.35 g/moles,
codeine (C₁₈H₂₁NO₃) with a molar mass of 299.36 g/moles,
norfenefrine (C₈H₁₁NO₂) with a molar mass of 153.18 g/moles, or
fructose (C₆H₁₂O₆) with a molar mass of 180.16 g/moles.

When 82 mg of the powder is dissolved in 1.50 mL of ethanol (density = 0.789 g/cm³, normal freezing point −114.6°C, Kf = 1.99°C/m), the freezing point is lowered to −115.5°C.

<u>Question: </u>What is the identity of the white powder?

<u>The Process:</u>

Let us identify the solute, the solvent, initial, and final temperatures.

The solute = the powder
The solvent = ethanol
The freezing point of the solvent = −114.6°C
The freezing point of the solution = −115.5°C

Prepare masses of solutes and solvents.

Mass of solute = 82 mg = 0.082 g
Mass of solvent = density x volume, i.e., $\boxed{ \ 0.789 \ \frac{g}{cm^3} \times 1.50 \ cm^3 = 1.1835 \ g = 0.00118 \ kg \ }$

We must prepare the solvent mass unit in kg because the unit of molality is the mole of the solute divided by the mass of the solvent in kg.

The molality formula is as follows:

$\boxed{ \ m = \frac{moles \ of \ solute}{kg \ of \ solvent} \ } \rightarrow \boxed{ \ m = \frac{mass \ of \ solute \ (g)}{molar \ mass \ of \ solute \times kg \ of \ solvent} \ }$

Now we combine it with the formula of freezing point depression.

$\boxed{ \ \Delta T_f = K_f \times \frac{mass \ of \ solute \ (g)}{molar \ mass \ of \ solute \times kg \ of \ solvent} \ }$

It is clear that we will determine the molar mass of the solute (denoted by Mr).

We enter all data into the formula.

$\boxed{ \ -114.6^0C - (-115.5^0C) = 1.99 \frac{^0C}{m} \times \frac{0.082 \ g}{Mr \times 0.00118 \ kg} \ }$

$\boxed{ \ 0.9 = \frac{1.99 \times 0.082}{Mr \times 0.00118} \ }$

$\boxed{ \ Mr = \frac{0.16318}{0.9 \times 0.00118} \ }$

We get $\boxed{ \ Mr = 153.65 \ }$

These results are very close to the molar mass of norfenefrine which is 153.18 g/mol. Thus the white powder is norfenefrine.

<h3>Learn more</h3>

The molality and mole fraction of water brainly.com/question/10861444
About the mass and density of ethylene glycol as an antifreeze brainly.com/question/4053884
About the solution as a homogeneous mixture brainly.com/question/637791

Keywords: a mysterious white powder, sugar, cocaine, codeine, norfenefrine, fructose, the solute, the solvent, dissolved, ethanol, normal freezing point, the freezing point depression, the identity

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3 years ago

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A fat is composed of long chains of carbon and hydrogen atoms. In a reaction with a strong base, a fat forms a soap and glycerol

Nonamiya [84]

Answer:

Empirical formula is C₉H₁₅O

Molecular formula = C₈₁H₁₃₅O ₉

Explanation:

Percentage of carbon = 77.60%

Percentage of oxygen = 11.45%

Percentage of hydrogen = 10.95%

Molecular weight = 1253 g/mol

Molecular formula = ?

Empirical formula = ?

Solution:

Number of gram atoms of C = 77.60 g /12g/mol =6.5

Number of gram atoms of O = 11.45 g / 16 g/mol = 0.72

Number of gram atoms of H = 10.95 g / 1.008 g/mol= 10.9

Atomic ratio:

C : H : O

6.5/0.72 : 10.9/0.72 : 0.72/0.72

9 : 15 : 1

C : H : O = 9 : 15 : 1

Empirical formula is C₉H₁₅O

Molecular formula:

Molecular formula = n (empirical formula)

n = molar mass of compound / empirical formula mass

n = 1253 / 139

n = 9

Molecular formula = n (empirical formula)

Molecular formula = 9 (C₉H₁₅O )

Molecular formula = C₈₁H₁₃₅O ₉

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3 years ago

An endothermic process is one in which heat is ________ from the surroundings.1) gained 2.) increased 3.) lost 4.) repelled

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The answer is 1) gained

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How many nitrogen atoms are in NH3?

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Three
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