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3 years ago

What is the molality of a solution of Fe(ClO3), in water that freezes at -2.72°C?

Chemistry

1 answer:

Anon25 [30]3 years ago

3 0

Answer:

0.366m = Molality of the solution

Explanation:

To solve this question we must know the addition of a solute produce decreasing in freezing point regard to the pure solvent. The equation is:

ΔT = m*Kf*i

<em>Where ΔT is change in freezing point </em>

(As freezing point of water is 0°C, the ΔT is 2.72°C)

<em>Kf is freezing point depression constant = 1.86°C/m for water</em>

<em>i is Van't Hoff factor. The number of ions produced when 1 mole of the salt is dissolved = 4 ions for Fe(ClO₃)₃, Fe³⁺ and 3 ClO₃⁻ ions</em>

<em>m is molality of the solution.</em>

<em />

Replacing:

2.72°C = m*1.86°C/m*4

<h3>0.366m = Molality of the solution</h3>

<em />

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If an atom has 35 protons in the nucleus, how many will it have orbiting nucleus

yan [13]

It will have 35 ''electrons'' . Basically the number of protons in the nucleus of an atom is always equal to the number of electrons but its just that protons are positively charged and electrons are negatively charged. <span />

8 0

3 years ago

What is the density of a substance that has a mass of 20 g and a volume of<br> 10 mL?

Paha777 [63]

Answer:

That unknown substance is water

Explanation:

3 0

3 years ago

Having done the experiment, explain briefly how the mass of zinc not equal the mass of lead gained (hint: the periodic table)

masya89 [10]

Answer:

Due to the difference in the relative atomic masses and therefore, the molecular masses of Zn and Pb, one mole of Zn is about 3.2 times lighter than one mole of Pb

Explanation:

From the periodic table, we have;

The atomic number of zinc, Zn = 30

The atomic mass of zinc, Zn = 65.38 amu

The molar mass of zinc, Zn = 65.38 g/mol

The atomic number of lead, Pb = 82

The atomic mass of lead, Pb = 207.2 amu

The molar mass of lead, Pb = 207.2 g/mol

Therefore, whereby equal number of moles of Zn is lost and Pb is gained, we have;

Mass of 1 mole of Zn = 65.38 grams

Therefore, 1 gram of Zn = 1/65.38 moles = 0.0153 moles

0.12 grams of Zn = 0.12×0.0153 = 0.00184 moles of Zn

Given that equal number of moles of Zn and Pb are involved in the reaction, the number of moles of Pb gained = 0.00184 moles

The mass of Pb gained = Number of moles of Pb gained × Molar mass of Pb

The mass of Pb gained = 0.00184 × 207.2 = 0.38 g ≈ 0.4 g.

Amount of Pb gained = 0.43 g ≈ 0.4 g

4 0

3 years ago

A chemist has 3.55x1022 molecules of nitrogen monoxide. How

Alina [70]

Answer:

<h2>0.059 moles</h2>

Explanation:

To find the number of moles in a substance given it's number of entities we use the formula

$n = \frac{N}{L} \\$

where n is the number of moles

N is the number of entities

L is the Avogadro's constant which is

6.02 × 10²³ entities

From the question we have

$n = \frac{3.55 \times {10}^{22} }{6.02 \times {10}^{23} } \\ = 0.05897...$

We have the final answer as

<h3>0.059 moles</h3>

Hope this helps you

6 0

3 years ago

X-rays had a frequency of about 3x10^18 determine it's wavelength (in nm) and energy per photon

Serggg [28]

Answer:

E = 19.89×10⁻¹⁶ J

λ = 1×10⁻¹ nm

Explanation:

Given data:

Frequency of xray = 3×10¹⁸ Hz

Wavelength of xray = ?

Energy of xray = ?

Solution:

speed of wave = wavelength × frequency

speed = 3×10⁸ m/s

3×10⁸ m/s = λ ×3×10¹⁸ s⁻¹

λ = 3×10⁸ m/s / 3×10¹⁸ s⁻¹

λ = 1×10⁻¹⁰m

m to nm:

λ = 1×10⁻¹⁰m×10⁹

λ = 1×10⁻¹ nm

Energy of x-ray:

E = h.f

h = plancks constant = 6.63×10⁻³⁴ Js

by putting values,

E = 6.63×10⁻³⁴ Js ×3×10¹⁸ s⁻ ¹

E = 19.89×10⁻¹⁶ J

7 0

2 years ago