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3 years ago

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Which balanced redox reaction is occurring in the voltaic cell represented by the notation of A l ( s ) | A l 3 ( a q ) | | P b

2 ( a q ) | P b ( s )

1 answer:

telo118 [61]3 years ago

7 0

Answer:

i dont know

Explanation:

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PLEASE ANSWER Which is/are true?

Alona [7]

You have to check each statement, so this is equivalent to 5 different questions.

<u>Answers:</u>

The true statements are:

b. Si has valence electrons in the n = 3 energy level.

d. Xe has valence electrons in the n = 5 energy level.

<u>Explanations:</u>

<u>a. Li has valence electrons in the n = 1 energy level.</u>

<u>Answer: False.</u>

<em>Valence electrons</em> are the electrons in the outermost main energy level (shell of electrons).

To determine where the valence electrons are, you build the electron configuration, using Aufbau rules to predict the orbital filling: in increasing order of energy.

The atomic number of lithium (Li) is 3. Hence, you have to distribute 3 electrons, and so its electron confiuration is:

1s² 2s¹

The only valence electron is in the 2s orbital, i.e. in the n = 2 energy level.

<u>b. Si has valence electrons in the n = 3 energy level.</u>

<u>Answer: True</u>

Silicon (Si) has atomic number 14, so you have to distribute 14 electrons in increasing order of energy:

1s² 2s² 2p⁶ 3s² 3p²

Thus, Si has five valence electrons, and they are in the n = 3 energy level.

<u>c. Ga has valence electrons in the n = 3 energy level.</u>

<u>Answer: False</u>

Gallium has atomic number 31, so you have to distribute 31 electrons, filling the orbitals in increasing order of enery.

1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p¹

The highest energy level is 4. This is where the valence electrons are. So, Ga has the valence electrons in the n = 4 level (not n = 3 as the statement describes).

<u>d. Xe has valence electrons in the n = 5 energy level.</u>

<u>Answer: True</u>

The atomic number of Xe is 54.

Using the short notation (noble gas notation), and filling the orbitals in increasing order of energy, you get the configuration:

[Kr] 5s² 4d¹⁰ 5p⁶.

Hence, the valence electrons are in the n ) 5 level, such as the statement describes.

<u>e. P has valence electrons in the n = 2 energy level.</u>

<u>Answer: False</u>

Phosphorus (P) has atomic number 15, hence there are 15 electrons.

The electron configuration following the increasing order of energy, which you can remember using Aufbau rules, is:

1s² 2s² 3s² 3p³

Then, the valence electrons are in the n = 3 energy level; not in the n = 2 energy level.

3 0

3 years ago

Choose specific acid-base conjugate pairs to make the following buffers: (a) pH ≈ 3.5;

leva [86]

$Our \ goal \ here\ is \ to \ find \ an \ acid-base \ conjugate \ pair \ that \ have \a \\\$pK_a-p H$. This is because we assume that the acid-base conjugate pair have an equal concentration to be considered an effective buffer.$

$p H-p K_a+\log \frac{\left[A^{-}\right]}{[H A]}$

$Where $\left[A^{-}\right]-[H A]$, so $\log \frac{\left[A^{-}\right]}{[H A]}-\log 1-0_{\text {so ... }}$$

pH-pKa

$Solve for $K_a$.$

$\begin{aligned}p H-p K_a &--\log K_a \\K_a &-10^{-p H} \\&-10^{-3.5} \\K_a &-3.2 \times 10^{-4}\end{aligned}$

$$$The nearest pairs are $\mathrm{HCOCOOH} / \mathrm{HCOCOO}^{-}$with a $\mathrm{K}_{\mathrm{a}}-3.5 \times 10^{-4}$,$

$$\mathrm{HOCH}_2 \mathrm{CH}(\mathrm{OH}) \mathrm{COOH} / \mathrm{HOCH}_2 \mathrm{CH}(\mathrm{OH}) \mathrm{COO}^{-}$with a $\mathrm{K}_{\mathrm{a}}-2.9 \times 10^{-4}$, and$

$$\mathrm{CH}_3 \mathrm{COOC}_6 \mathrm{H}_4 \mathrm{COOH} / \mathrm{CH}_3 \mathrm{COOC}_6 \mathrm{H}_4 \mathrm{COO}^{-}$with a $\mathrm{K}_a-3.6 \times 10^{-4}$. We can also check for the $\mathrm{K}_b$. First, solve for $p K_b$ then the $K_b$ -$

$\begin{aligned}p K_w &-p K_b+p K_a \\p K_b &-p K_w-p K_a \\&-14-3.5 \\p K_b &-10.5 \\p K_b &--\log K_b \\K_b &-10^{-p K_b} \\&-10^{-10.5} \\K_b &-3.2 \times 10^{-11}\end{aligned}$

$There \ are\ no \ pairs \ near \ this \ $K_b$ value.$

<h3>What is a conjugate acid and base pair?</h3>

An acid-base pair that differs by one proton is referred to as a conjugate pair. A conjugate acid-base pair is a pair of substances that can both absorb and donate hydrogen ions to one another. A proton is added to the compound to create the conjugate acid, and a proton is taken out to create the conjugate base. When a proton is supplied to a base, a conjugate acid is created, and vice versa when a proton is taken away from an acid, a conjugate base is created.

To learn more about conjugate acid and base pair, visit;

brainly.com/question/10468518

#SPJ4

4 0

2 years ago

If the mass of a sample of Mg is 0.500 g and is placed in 100.0 g of HCl, the heat gained is 546.5 J. What is the change in temp

ale4655 [162]

Answer:

1.36 K

Explanation:

We have the following data:

The heat gained by HCl is calculated as:

heat = m x Sh x ΔT

where m is the mass of HCl (100.0 g), Sh is the specific heat of HCl (4.017 J/K.g) and ΔT is the change in temperature. We introduce the data in the mathematical expression to calculate ΔT as follows:

ΔT = heat/(m x Sh) = 546.5 J/(100.0 g x 4.017 J/K.g) = 1.36 K

Therefore, the change in temperature is 1.36 K.

3 0

3 years ago

The core of an atom contains protons and __________.. .

alexira [117]

The core of an atom contains protons and neutrons.

4 0

3 years ago

Read 2 more answers

If I add 475mL of water to 75.0mL of a 0.315M NaOH solution, what will the molarity of the diluted solution be?

pantera1 [17]

Answer is: <span>the molarity of the diluted solution 0,043 M.
</span>V(NaOH) = 75 mL ÷ 1000 mL/L = 0,075 L.
c(NaOH) = 0,315 M = 0,315 mol/L.
n(NaOH) = c(NaOH) · V(NaOH).
n(NaOH) = 0,075 L · 0,315 mol/L.
n(NaOH) = 0,023625 mol.
V(solution) = 0,475 L + 0,75 L.
c(solution) = 0,023625 mol ÷ 0,550 L.
c(solution) = 0,043 mol/L.

5 0

4 years ago