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3 years ago

How many moles of CaO will be produced from 23.9 g of Ca?2Ca(s) + O2(g) – 20:0(3)mol

Chemistry

1 answer:

inessss [21]3 years ago

4 0

Answer:

0.6 moles of CaO will produced.

Explanation:

Given data:

Mass of calcium = 23.9 g

Moles of CaO produced = ?

Solution:

Chemical equation:

2Ca + O₂ → 2CaO

Number of moles of calcium:

Number of moles = mass/ molar mass

Number of moles = 23.9 g / 40 g/mol

Number of moles = 0.6 mol

Now we will compare the moles of calcium and CaO.

Ca : CaO

2 : 2

0.6 : 0.6

0.6 moles of CaO will produced.

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A 100.0 mL solution containing 0.864 g of maleic acid (MW=116.072 g/mol) is titrated with 0.276 M KOH. Calculate the pH of the s

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Answer:

pH = 1.32

Explanation:

H₂M + KOH ------------------------ HM⁻ + H₂O + K⁺

This problem involves a weak diprotic acid which we can solve by realizing they amount to buffer solutions. In the first deprotonation if all the acid is not consumed we will have an equilibrium of a wak acid and its weak conjugate base. Lets see:

So first calculate the moles reacted and produced:

n H₂M = 0.864 g/mol x 1 mol/ 116.072 g = 0.074 mol H₂M

54 mL x 1L / 1000 mL x 0. 0.276 moles/L = 0.015 mol KOH

it is clear that the maleic acid will not be completely consumed, hence treat it as an equilibrium problem of a buffer solution.

moles H₂M left = 0.074 - 0.015 = 0.059

moles HM⁻ produced = 0.015

Using the Henderson - Hasselbach equation to solve for pH:

ph = pKₐ + log ( HM⁻/ HA) = 1.92 + log ( 0.015 / 0.059) = 1.325

Notes: In the HH equation we used the moles of the species since the volume is the same and they will cancel out in the quotient.

For polyprotic acids the second or third deprotonation contribution to the pH when there is still unreacted acid ( Maleic in this case) unreacted.

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3 years ago

Which statement below about contrasting Hb and Mb is FALSE?

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C. Hb binds O2 more tightly than Mb.

Explanation:

Hb and Mb are both oxygen carrier protiens which contain the heme group. Hb has 4 heme units in 1 moleucle which work via coperative effect. On the other hand, Mb has only one heme unit.

From above theory, statement A and B are correct.

Although the heme group of the Mb is identical to those of Hb, Mb has a higher affinity for carrying oxygen than hemoglobin.

Hence, Statement C is wrong.

Thats why the function of hemoglobin is to transport oxygen and that of myoglobin is to store oxygen.

When a curve is plotted between oxygen accepted and the pressure of the oxygen, Hb shows sigmoidal, whereas Mb shows hyperbolic oxygen saturation curves. The statement D is correct.

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3 years ago

Which of the following isoelectronic series is correctly ranked from largest ionic radius to smallest ionic radius? 1. N 3−, O 2

love history [14]

Answer:

Option 1: N⁻³ > O⁻² > F⁻ > Na⁺ > Mg⁺²

Explanation:

Ionic radius is the radius of an atom´s ion in ionic crystal structure. In an ion that lose an electron, to form a cation, the radius of the ion gets smaller, because the repulsion between electrons decrease because fewer electrons are present. Conversely, adding on electron to a neutral atom, to form an anion, causes electron - electron repulsions to increase, so the size of the radius of the ion gets bigger.

Isoelectronic species are ions or elements that have the same number of electrons in their electronic shells but have different overall charges, because of their different atomic numbers.

In a isolelectronic series (same number of electrons), the increase of the positive charge (given by the number of protons in the nucleus), will cause a decrease in radius beacuse the greater electrostatic attraction between the electrons and the nucleus. Consequently, the ion with the greatest nuclear charge will have the smallest ionic radius and the ion with the smallest nulear charge will have the largest ionic radius.

We will use this principle to solve our problem.

In our case, the given ions are:

N⁻³ : Z = 7, e⁻ = 10
O⁻²: Z= 8, e⁻ =10
F⁻: Z = 9, e⁻ = 10
Na⁺: Z= 11, e⁻ = 10
Mg⁺²: Z=12, e⁻ =10

where Z= number of protons, and e⁻ = number of electrons.

Hence the decreasing order of ionic radius is:

N⁻³ > O⁻² > F⁻ > Na⁺ > Mg⁺²

Have a nice day!

4 0

2 years ago

How many moles of CaO will be produced from 23.9 g of Ca?2Ca(s) + O2(g) – 20:0(3)mol​

How many moles of CaO will be produced from 23.9 g of Ca?2Ca(s) + O2(g) – 20:0(3)mol