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2 years ago

How many molecules of F2 are there in 4.2 mol F2?

Chemistry

1 answer:

zhannawk [14.2K]2 years ago

7 0

Hey there!

1 mol has 6.022 x 10²³ molecules.

If we have 4.2 mol F₂, multiply the number of molecules in 1 mol by 4.2.

4.2 x 6.022 x 10²³

2 sig figs

25 x 10²³

Put this properly into scientific notation.

2.5 x 10²⁴ molecules of F₂

Hope this helps!

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If A is slowly added to a solution containing 0.0500 M of B and 0.0500 M of C, which solid will precipitate first? The solubilit

OleMash [197]

Answer:

AC₄ will precipitate out first.

Explanation:

A solid will precipitate out if the ionic product of the solution exceeds the solubility product.

Let us check the ionic product

a) A₂B₃

Ionic product = [A]²[B]³

[A] = say "s"

[B] = 0.05 , [B]³ = (0.05)³ = 0.000125

2.3 X 10⁻⁸ = [A]²(0.000125)

[A] = 0.0136

b) AC₄

Ionic product = [A] [C]⁴

[A] = "s"

[A][0.05]⁴ = 4.10 X 10⁻⁸

[A]=0.00656 M

So for ionic product to exceed solubility product, we need less concentration of A in case of AC₄.

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2 years ago

Calculate the Lattice Energy of KCl(s) given the following data using the Born-Haber cycle: ΔHsublimation K = 79.2 kJ/mol IE1 K

DanielleElmas [232]

Answer:

Explanation:

The following equation relates to Born-Haber cycle

$\triangle H_f = S + \frac{1}{2} B + IE_M - EA_X+ U_L$

Where

$\triangle H_f$ is enthalpy of formation

S is enthalpy of sublimation

B is bond enthalpy

$IE_M$ is ionisation enthalpy of metal

$EA_X$ is electron affinity of non metal atom

$U_L$ is lattice energy

Substituting the given values we have

-435.7 = 79.2 + 1/2 x 242.8 + 418.7 - 348 +U_L

$U_L$ = - 707 KJ / mol

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2 years ago

Arsenic produces a blue flame when heated. Calcium produces an orange-red flame. Which of these best explains why this differenc

MrMuchimi

Flame colors are produced from the movement of the electrons in the metal ions present in the compounds. When you heat it, the electrons gain energy and can jump into any of the empty orbitals at higher levels Each of these jumps involves a specific amount of energy being released as light energy, and each corresponds to a particular color. As a result of all these jumps, a spectrum of colored lines will be produced. The color you see will be a combination of all these individual colors.

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2 years ago

Calculate the amount, in moles, of PO43- present at equilibrium when excess Sr3(PO4)2 is added to 750. mL 1.2 M Sr(NO3)2(aq). As

Crank

Answer:

1.8 × 10⁻¹⁶ mol

Explanation:

(a) Calculate the solubility of the Sr₃(PO₄)₂

Let s = the solubility of Sr₃(PO₄)₂.

The equation for the equilibrium is

Sr₃(PO₄)₂(s) ⇌ 3Sr²⁺(aq) + 2PO₄³⁻(aq); Ksp = 1.0 × 10⁻³¹

1.2 + 3s 2s

$K_{sp} =\text{[Sr$^{2+}$]$^{3}$[PO$_{4}^{3-}$]$^{2}$} = (1.2 + 3s)^{3}\times (2s)^{2} = 1.0 \times 10^{-31}\\\text{Assume } 3s \ll 1.2\\1.2^{3} \times 4s^{2} = 1.0 \times 10^{-31}\\6.91s^{2} = 1.0 \times 10^{-31}\\s^{2} = \dfrac{1.0 \times 10^{-31}}{6.91} = 1.45 \times 10^{-32}\\\\s = \sqrt{ 1.45 \times 10^{-32}} = 1.20 \times 10^{-16} \text{ mol/L}\\$

(b) Concentration of PO₄³⁻

[PO₄³⁻] = 2s = 2 × 1.20× 10⁻¹⁶ mol·L⁻¹ = 2.41× 10⁻¹⁶ mol·L⁻¹

(c) Moles of PO₄³⁻

Moles = 0.750 L × 2.41 × 10⁻¹⁶ mol·L⁻¹ = 1.8 × 10⁻¹⁶ mol

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2 years ago

What happens to the total mass of a substance undergoing a physical change

yKpoI14uk [10]

That depends. What kind of change are you talking about? But

Mass through chemical change stays the same as well. Example: burning paper, the ash left behind is not all of the mass of the reactants, Carbon dioxide, and other substances also makeupmass but just is not seen

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2 years ago

Read 2 more answers