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1 year ago

Fill in the blanks to complete the table

Chemistry

1 answer:

aleksandrvk [35]1 year ago

3 0

The atomic number(Z) is equal to the number of protons to equal to number of electrons.

The number of neutrons is equal to atomic mass minus the atomic number

n=A-Z

For Zn^2+, Z=28, e=28

For iron, Z=25,A=55

The number of neutrons is 55-25=30

The charge is zero

For O^2-, Z=8+2=10, n=p=10

The number of neutrons is 16-10=6

For sulfur, Z=16,A=34

For S2-, Z=16+2=18, A=34

The charge is 2-

The atomic number is the basis of the periodic table.
It is equal to the number of protons.
The number of neutrons is atomic mass minus atomic number.

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An unknown compound, X is thought to have a carboxyl group with a pKa of 2.0 and another ionizable group with a pKa between 5 an

Westkost [7]

Answer:

7.3

Explanation:

By Henderson Hasselbalch equation we can calculate the pH or the pOH of a solution by its pKa. Remember that $pH = -log[H^{+}]$ , and pKa = -logKa. Ka is the equilibrium constant of the acid.

Henderson Hasselbalch equation :

$pH = pKa - log \frac{[HA]}{[A^{-}]}$

Where [HA] is the concentration of the acid, and $[A^{-}]$ is the concentration of the anion which forms the acid.

So, acid X, has two ionic forms, the carboxyl group and the other one. First, we have 0.1 mol/L of the acid, in 100 mL, so the number of moles of X

n1 = (0.1 mol/L)x(0.1 L) = 0.01 mol

When it dissociates, it forms 0.005 mol of the carboxyl group and 0.005 mol of the other group. Assuming same stoichiometry.

Adding NaOH, with 0.1 mol/L and 75 mL, the number of moles of $OH^-$ will be

n2 = (0.1 mol/L)x(0.075 L) = 0.0075 mol

So, the 0.0075 mol of $OH^-$ reacts with 0.005 mol of carboxyl, remaining 0.0025 mol of $OH^-$ , which will react with the 0.005 mol of the other group. So, it will remain 0.0025 mol of the other group.

The final volume of the solution will be 175 mL, but both concentrations (the acid form and ionic form) have the same volume, so we can use the number of mol in the equation.

Note that, the number of moles of the acid form is still 0.01 mol because it doesn't react!

So,

$6.72 = pKa - log \frac{0.01}{0.0025}$

6.72 = pKa - log 4

pKa - log4 = 6.72

pKa = 6.72 + log4

pKa = 6.72 + 0.6

pKa = 7.3

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3 years ago

The Law of Conservation of Mass states that ____

Vaselesa [24]

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3 years ago

Which contains more atoms, 10. 00 g of aluminum or 10. 00 g of lead? Can you explain without using mathematical conversions?.

Aleks04 [339]

Explanation:

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3 years ago

What do scientists use the term “light-year” to describe?

Tatiana [17]

Answer:

Astronomers measure distance in space or the distance light travels in one Earth year.

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3 years ago

Ammonia (nh3) chemically reacts with oxygen gas to produce nitric oxide and water. What mass of nitric oxide is produced by the

vichka [17]

Ammonia yields nitric oxide and water in the presence of oxygen. The mass of nitric acid that will be produced from 6.40 gm of oxygen is 4.8 grams.

Mass is the product of the moles of the substance and its molar mass. it is given as,

$\rm mass = moles \times molar\; mass$

The balanced chemical reaction is shown as:

$\rm 4NH_{3} + 5O_{2} \rightarrow 4NO + 6H_{2}O$

Moles of oxygen are calculated by mass, 6.40 gm as,

$\begin{aligned} \rm moles &= \rm \dfrac{mass}{molar\; mass}\\\\&= \dfrac{6.40}{32}\\\\&= 0.2\;\rm moles \end{aligned}$

From the reaction, the molar ratio of nitric oxide to oxygen is 4: 5 and is used to calculate the moles of nitric oxide as,

$0.2 \times \dfrac{4}{5} = 0.16$

0.16 moles and molar mass, 30 of nitric oxide is used to calculate the mass as,

$0.16 \times 30 = 4.8 \;\rm gm$

Therefore, 4.8 grams of nitric oxide will be produced.

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2 years ago