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3 years ago

Atoms- 1 2 3 4

Chemistry

1 answer:

liq [111]3 years ago

7 0

Answer:

The ones with 8 protons

Explanation:

Since there are two of them with 8 protons, we can assume they are the same element. The first 8 proton element has 10 neutrons while the second has 11. This makes them isotopes of one another

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A nickle is about 2 millimeters thick, or 2/1000 of a meter.how many nanometers is this?

Softa [21]

You know that you can just google it right? It has this converter.

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4 years ago

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

7 0

3 years ago

Read 2 more answers

The Spirit of America Goodyear blimp has a volume of 2.027×105 ft3.When the blimp is in operation, it is filled with helium gas.

Andru [333]

Answer: 1.027 x 10^6 g= 1027kg
In this question, you are given the volume of the blimp (2.027×10^5 ft^3) and the density of the gas(0.179g/L). To answer this question, you need to convert the volume unit into liter. The calculation would be: 2.027×10^5 ft^3 x 28.3168L/ft3= 57.398 x 10^5L= 5.74x10^6L

Then to find the mass, multiply the volume with the density. The calculation would be: 5.74x10^6L x 0.179g/L= 1.027 x 10^6 g= 1027kg

4 0

3 years ago

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If you have ever peeled the label off a glass jar, you may have noticed that the glue does not easily wash off with water. Howev

shepuryov [24]

Answer:

It can be removed by acidic chemicals

Explanation:

8 0

3 years ago

To what volume should you dilute 134 mL of an 8.00 M CuCl2 solution so that 48.0 mL of the diluted solution contains 5.89 g CuCl

Tom [10]

Answer:

Explanation:

Number of moles of CuCl2 initially present = volume * molar concentration

= 0.134 * 8

= 1.072 mol.

Molar mass of CuCl2 = 63.5 + (2*35.5)

= 134.5 g/mol

Mass of CuCl2 = molar mass * number of moles

= 134.5 * 1.072

= 144.184 g

Mass of CuCl2 in 48 ml = 5.89 g in 48 ml

Volume = 5.89 * (48/144.184)

= 1.96 ml.

4 0

3 years ago