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2 years ago

If an atom has 10 protons and electrons how many of the electrons will be valence electrons?

Chemistry

2 answers:

Snezhnost [94]2 years ago

7 0

Answer:

8 of the electrons will be valence electrons

Explanation:

insens350 [35]2 years ago

4 0

Answer:

8 valence electrons

Explanation:

We are given the atom has 10 electrons.

The first electron shell holds 2 electrons (maximum)

The second electron shell holds 8 electrons (maximum)

2+8=10

Therefore we would have 2 electrons in the first shell and 8 in the second.

Valence electrons are the outermost electron, and since the second shell is the outermost for the atom, it has 8 valence electrons.

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"How much NH4Cl, when present in 2.00 liters of 0.200 M ammonia, will give a solution with pH = 8.20? For NH3, Kb = 1.8 x 10-5"

Andru [333]

Answer:

245.66g of NH₄Cl is the mass we need to add to obtain the desire pH

Explanation:

The mixture of NH3/NH4Cl produce a buffer. We can find the pH of a buffer using H-H equation:

pH = pKa + log [A⁻] / [HA]

Where [A⁻] is the molar concentration of the base, NH₃, and [HA] molar concentration of the acid, NH₄⁺. This molar concentration can be taken as the moles of each chemical

First, we need to find pKa of NH₃ using Kb. Then, the moles of NH₃ and finally replace these values in H-H equation to solve moles of NH₄Cl we need to obtain the desire pH.

pKa NH₃/NH₄⁺

pKb = - log Kb

pKb = -log 1.8x10⁻⁵ = 4.74

pKa = 14 - pKb

pKa = 14 - 4.74

pKa = 9.26

Moles NH₃

2.00L ₓ (0.200mol NH₃ / L) = 0.400 moles NH₃

H-H equation:

pH = pKa + log [NH₃] / [NH₄Cl]

8.20 = 9.26 + log [0.400 moles] / [NH₄Cl]

-1.06 = log [0.400 moles] / [NH₄Cl]

0.0087 = [0.400 moles] / [NH₄Cl]

[NH₄Cl] = 0.400 moles / 0.0087

[NH₄Cl] = 4.59 moles of NH₄Cl we need to add to original solution to obtain a pH of 8.20. In grams (Using molar mass NH₄Cl=53.491g/mol):

4.59 moles NH₄Cl ₓ (53.491g / mol) =

<h3>245.66g of NH₄Cl is the mass we need to add to obtain the desire pH</h3>

3 0

4 years ago

Use the balanced equation to solve the problem.

harkovskaia [24]

Answer:

4.20 moles NF₃

Explanation:

To convert between moles of N₂ and NF₃, you need to use the mole-to-mole ratio from the balanced equation. This ratio consists of the coefficients of both molecules from the balanced equation. The molecule you are converting from (N₂) should be in the denominator of the ratio because this allows for the cancellation of units. The final answer should have 3 sig figs because the given value (2.10 moles) has 3 sig figs.

1 N₂ + 3 F₂ ---> 2 NF₃

2.10 moles N₂ 2 moles NF₃
--------------------- x --------------------- = 4.20 moles NF₃
1 mole N₂

7 0

2 years ago

Which missing item would complete this beta decay reaction?

Karo-lina-s [1.5K]

The question is incomplete. Complete question is attached below:
.................................................................................................................

Correct Answer is : 54 131Xe

Reason:
Emission of beta particle from radioactive material increases atomic number by one, but atomic mass number donot change.

In present case, the reactant is 53 131 I. When, iodine emits beta particle i.e. electron, it atomic number increases by one. Hence, it gets converted into Xe. Atomic number of Xenon is 54.

7 0

3 years ago

Read 2 more answers

Predict which of the two orders is preferred. Choose one: HOCl is the preferred arrangement. HClO is the preferred arrangement.

Artyom0805 [142]

Answer:

HOCl is the preferred arrangement.

Explanation:

Hypochlorous acid (HOCl or HClO) is a weak acid that contains Hydrogen, Chlorine and oxygen. Generally both are accurate molecular formulars as hey show the exact number of atoms of elements present in the compound.

However the preferred formular is HOCl. The reason for this is because HOCl implies the molecular structure (that is, how the atoms are bonded to each other). The H is bonded to the O and the O in turn is being bonded to the Cl. HClO on the other hand says nothing about the molecular structure.

4 0

3 years ago

What is the mole ratio of PbO2 to water? PbO, H,0 = 1:0

ipn [44]

Answer:

The mole ratio of PbO2 to H2O is 1 : 2.

Explanation:

The balanced reaction equation is:

Pb + PbO2 + 2H2SO4 → 2PbSO4 + 2H2O

On the reactant side, we have 1 mole of Pb, 1 mole of PbO2, 2 moles of H2SO4.

On the product side, we have 2 moles of PbSO4 and 2 moles of H2O.

This means that for ever 1 mole of PbO2 consumed, 2 moles of water is formed as product.

Hence, the mole ratio of PbO2 to H2O is 1 : 2.

5 0

3 years ago