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3 years ago

Which statement about Bohr’s model of the atom is false?

Chemistry

2 answers:

AfilCa [17]3 years ago

3 0

Answer:

Bohr o saka mi ad ha piebald webs ldb

Explanation:

mihalych1998 [28]3 years ago

3 0

B because an electron doesn’t follow a certain path.

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A certain liquid has a normal boiling point of and a boiling point elevation constant . A solution is prepared by dissolving som

jek_recluse [69]

The question is incomplete, the complete question is:

A certain substance X has a normal freezing point of $-6.4^oC$ and a molal freezing point depression constant $K_f=3.96^oC.kg/mol$ . A solution is prepared by dissolving some glycine in 950. g of X. This solution freezes at $-13.6^oC$ . Calculate the mass of urea that was dissolved. Round your answer to 2 significant digits.

Answer: The mass of glycine that can be dissolved is $1.3\times 10^2g$

Explanation:

Depression in the freezing point is defined as the difference between the freezing point of the pure solvent and the freezing point of the solution.

The expression for the calculation of depression in freezing point is:

$\text{Freezing point of pure solvent}-\text{freezing point of solution}=i\times K_f\times m$

$\text{Freezing point of pure solvent}=\text{Freezing point of solution}=i\times K_f\times \frac{m_{solute}\times 1000}{M_{solute}\times w_{solvent}\text{(in g)}}$ ......(1)

where,

Freezing point of pure solvent = $-6.4^oC$

Freezing point of solution = $-13.6^oC$

i = Vant Hoff factor = 1 (for non-electrolytes)

$K_f$ = freezing point depression constant = $3.96^oC/m$

$m_{solute}$ = Given mass of solute (glycine) = ?

$M_{solute}$ = Molar mass of solute (glycine) = 75.07 g/mol

$w_{solvent}$ = Mass of solvent = 950. g

Putting values in equation 1, we get:

$-6.4-(-13.6)=1\times 3.96\times \frac{m_{solute}\times 1000}{75.07\times 950}\\\\m_{solute}=\frac{7.2\times 75.07\times 950}{1\times 3.96\times 1000}\\\\m_{solute}=129.66g=1.3\times 10^2g$

Hence, the mass of glycine that can be dissolved is $1.3\times 10^2g$

5 0

3 years ago

100 mL of a buffer that consists of 0.20 M NH3 and 0.20 M NH4Cl is titrated with 25 mL of 0.20 M HCl. Calculate the pH of the re

Marrrta [24]

Answer:

pH = 9.03

Explanation:

The equilibrium of the NH₄Cl / NH₃ buffer in water is:

NH₃ + H₂O ⇄ NH₄⁺ + OH⁻

Initial moles of both NH₃ and NH₄⁺ are:

0.100L ₓ (0.20 mol / L) = 0.0200 moles

The NH₃ reacts with HCl producing NH₄⁺, thus:

NH₃ + HCl → NH₄⁺ + Cl⁻

That means, moles of HCl added to the solution are the same moles are consumed of NH₃ and produced of NH₄⁺

Moles added of HCl were:

0.025L ₓ (0.20mol / L) = 0.0050 moles of HCl. Thus, final moles of NH₃ and NH₄⁺ are:

NH₃: 0.0200 moles - 0.0050 moles = 0.0150 moles

NH₄⁺: 0.0200 moles + 0.0050 moles = 0.0250 moles.

Using H-H equation for bases:

pOH = pKb + log [NH₄⁺] / [NH₃]

Where pKb is -log Kb = 4.745.

Replacing:

pOH = 4.745 + log 0.0250mol / 0.0150mol

pOH = 4.967

As pH = 14- pOH

pH = 9.03

6 0

3 years ago

Which of the following solids would possess the lowest melting point?

saul85 [17]

The melting points of the compounds from the choices are listed below:

a. C25H52 -> +47 to +56 degrees celsius

b. Hg -> -38.83 degrees celsius

c. CaCl2 -> +772 degrees celsius

d. CuO -> +1326 degrees celsius

It is evident from the listed melting points above that mercury (Hg) has the lowest melting point. This is why mercury is liquid at room temperature.

4 0

3 years ago

Read 2 more answers

What is the median of the following set: 2, 4, 6, 8, and 10?

labwork [276]

Answer:9

Explanation:

(3+8+10+15)/4 = 36/4 = 9

6 0

3 years ago

Tiana is a chemist who is making a chemical to add to swimming pools in order to make the water safer. she mixed two solid subst

babymother [125]

Explanation:

chemical to add to swimming pools in order

to make the water safer. She mixed two solid

substances together in a sealed container.

The diagram above shows the repeating

groups of atoms that make up the two

starting substances.

After mixing, Tiana found two liquid

substances in the sealed container.

(Nothing had escaped.) Which of the

diagrams to the left shows the repeating

groups of atoms that make up the ending

substances?

8 0

3 years ago

Read 2 more answers