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3 years ago

The modern-day quantum model of the atom is better than John Dalton’s model because it

Chemistry

2 answers:

arsen [322]3 years ago

8 0

it answers many questions about atoms

Licemer1 [7]3 years ago

7 0

The modern day model of an atom has a lot of questions answered about it answered and is very accurate while John's version was a very early model before technology was advanced enough to get more information on it so it was very basic and not as accurate as today's model. Hope this helps!

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Why is it better to measure the percent change in mass<br> ratherthan just using the change in mass?

never [62]

Answer: The result is presented in proportion which gives a clearer understanding and accurate result.

Explanation: Percentage change in mass is the proportion of the initial mass of a substance changed after sometime. The results is presented as a percentage making it more accurate and can help to give future reference to weight calculations.

Change is Mass is the mass of a substance left after sometime mostly given in grams. It is not as accurate as percentage change in mass. It is generally better to show results in percentage change in mass as it gives a better understanding of what mass of a substance was lost after a given period or after application of energy like Heat or increased temperature.

6 0

3 years ago

Convert 23.92inHg to torr.

White raven [17]

<h3><u>Answer;</u> </h3>

= 607.568 Torr

<h3><u>Explanation; </u></h3>

1 in of mercury is equivalent to 25.4 Torr

Therefore;

23.92 InHg will be equal to;

23.92 × 25.4

<u>= 607.568 Torr</u>

7 0

3 years ago

What is the net ionic equation for the reaction<br> ofFeCl3 and KOH in water?

Levart [38]

Answer:

Fe³⁺(aq) + 3 OH⁻(aq) → Fe(OH)₃(s)

Explanation:

First, we will write the molecular equation because it is the easiest to balance.

FeCl₃(aq) + 3 KOH(aq) → Fe(OH)₃(s) + 3 KCl(aq)

The full ionic equation includes all the ions and the molecular species.

Fe³⁺(aq) + 3 Cl⁻(aq) + 3 K⁺(aq) + 3 OH⁻(aq) → Fe(OH)₃(s) + 3 K⁺(aq) + 3 Cl⁻(aq)

The net ionic equation includes only the ions that participate in the reaction and the molecular species.

Fe³⁺(aq) + 3 OH⁻(aq) → Fe(OH)₃(s)

8 0

3 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

How many protons, neutrons, and electrons does sodiums neutral atom have? Plz help.

rusak2 [61]

Answer:

So for your question, the Periodic Table tells us that sodium has an Atomic Number of 11, so there are 11 protons and 11 electrons. The Periodic Table tells us that sodium has an Atomic Mass of ≈23. So there are 23 - 11 = 12 neutrons.

Explanation:

3 0

3 years ago