What are two functions of dermal tissue in plants?

The voltage for the following cell is +0.731 V. Find Kb for the organic base RNH2. Use EscE 0.241V.

tino4ka555 [31]

Complete Question

The complete question is shown on the first uploaded image

Answer:

The value is $K_b = 1.89 *10^{-6}$

Explanation:

From the question we are told that

The voltage of the cell is $V = 0.731 \ V$

Generally $K_b$ is mathematically represented as

$K_b = \frac{K_w }{ K_a }$

Where $K_w$ is the equilibrium constant for this auto-ionization of water with a value $K_w = 1.0 *10^{-14}$

Generally the $E_{cell}$ is mathematically represented as

$E_{cell} = V - E_{SCE}$

=> $E_{cell} = 0.731 - 0.241$

=> $E_{cell} = 0.49 V$

This $E_{cell}$ is mathematically represented as

$E_{cell} = \frac{0.0592}{n} * log K_a$

Where n is the number of moles which in this question is n = 1

So

$0.490 = \frac{0.0592}{1} * log K_a$

=> $K_a = 5.30*10^{-9}$

So

$K_b = \frac{ K_w}{ K_a}$

=> $K_b = \frac{1.0 *10^{-14}}{ 5.30*10^{-9}}$

=> $K_b = 1.89 *10^{-6}$

5 0

3 years ago

Which ion will most likely form a precipitate when reacted with SO42 ?

Charra [1.4K]

<h2>Answer:Ba $^2+$ </h2>

Explanation:

option A:

$SO_{4}^{2-}$ is an anion and $Cl^{1-}$ is also an anion.So,there is no reaction.

option B:

$K^{+}$ reacts with $SO_{4}^{2-}$ to form $K_{2}SO_{4}$ .

Since $K$ is a first group element,all its salts are soluble in water.

Hence no precipitate is formed.

option C:

$Na^{+}$ reacts with $SO_{4}^{2-}$ to form $Na_{2}SO_{4}$ .

Since $Na$ is a first group element,all its salts are soluble in water.

Hence no precipitate is formed.

option D:

$Ba^{2+}$ reacts with $SO_{4}^{2-}$ to form $BaSO_{4}$ .

Solubility of sulphates of second group elements decrease down the group.

So, $BaSO_{4}$ is a precipitate.

6 0

3 years ago

In dry climates, rates of evaporation exceed what?

Dennis_Churaev [7]

<h2>Answer:</h2>

<u>In dry climates, rates of evaporation exceed precipitation</u>

<h2>Explanation:</h2>

Evaporation is an important process in the global water cycle. Sunrays hits the surface of water or land and causes water to change state from a liquid to a gas. This is what we call evaporation. When evaporation occurs, at the same time precipitation occurs in the atmosphere which is the water falling from the clouds as rain, freezing rain, sleet, snow, or hail. As the rate of evaporation increases, the rate of precipitations increases too because both are connected to each other.

3 0

3 years ago

How much does calcite coast

Nikitich [7]

Answer:

It depends on what kind and how much. Some are about $100, and others are $1,000.

5 0

4 years ago

A student measures out exactly 0.105 g of salicylic acid and runs the experiment as dictated in the lab manual. They obtain 0.11

scoray [572]

<u>Answer:</u> The percent yield of the reaction is 8.10 %.

<u>Explanation:</u>

To calculate the number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$ .....(1)

Given mass of salicylic acid = 0.105g

Molar mass of salicylic acid = 138.12 g/mol

Putting values in equation 1, we get:

$\text{Moles of salicylic acid}=\frac{0.105g}{138.12g/mol}=0.0079mol$

The chemical equation for the formation of aspirin from salicylic acid follows:

$\text{Salicylic acid + Acetic anhydride}\rightarrow \text{Aspirin + Acetic acid}$

By Stoichiometry of the reaction:

1 mole of salicylic acid produces 1 mole of aspirin

So, 0.0076 moles of salicylic acid will produce = $\frac{1}{1}\times 0.0076=0.0076mol$ of aspirin

Now, calculating the mass of aspirin from equation 1, we get:

Molar mass of aspirin = 180.16 g/mol

Moles of aspirin = 0.0076 moles

Putting values in equation 1, we get:

$0.0076mol=\frac{\text{Mass of aspirin}}{180.16g/mol}\\\\\text{Mass of aspirin}=(0.0076mol\times 180.16g/mol)=1.37g$

To calculate the percentage yield of aspirin, we use the equation:

$\%\text{ yield}=\frac{\text{Experimental yield}}{\text{Theoretical yield}}\times 100$

Experimental yield of aspirin = 0.111 g

Theoretical yield of aspirin = 1.37 g

Putting values in above equation, we get:

$\%\text{ yield of aspirin}=\frac{0.111g}{1.37g}\times 100\\\\\% \text{yield of aspirin}=8.10\%$

Hence, the percent yield of the reaction is 8.10 %.

6 0

3 years ago