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SpyIntel [72]
3 years ago
11

How many of the following species are paramagnetic? sc3+ br- mg2+ se?

Chemistry
1 answer:
Aloiza [94]3 years ago
8 0
Answer:
           One: <u>Selenium</u> is Paramagnetic

Explanation:
                   Those compounds which have unpaired electrons are attracted towards magnet. This property is called as paramagnetism. Lets see why remaining are not paramagnetic.

Electronic configuration of Scandium;

Sc  =  21  = 1s², 2s², 2p⁶, 3s², 3p⁶, 4s², 3d¹

Sc³⁺  =  1s², 2s², 2p⁶, 3s², 3p⁶ 

Hence in Sc³⁺ there is no unpaired electron.

Electronic configuration of Bromine;

Br  =  35  = 1s², 2s², 2p⁶, 3s², 3p⁶, 4s², 3d¹⁰, 4p⁵

Br⁻  =  1s², 2s², 2p⁶, 3s², 3p⁶, 4s², 3d¹⁰, 4p⁶

Hence in Br⁻ there is no unpaired electron.

Electronic configuration of Magnesium;

Mg  =  12  = 1s², 2s², 2p⁶, 3s²

Mg²⁺  =  1s², 2s², 2p⁶

Hence in Mg²⁺ there is no unpaired electron.

Electronic configuration of selenium;

Se  =  34  = 1s², 2s², 2p⁶, 3s², 3p⁶, 4s², 3d¹⁰, 4p⁴

Or,

Se  =  34  = 1s², 2s², 2p⁶, 3s², 3p⁶, 4s², 3d¹⁰, 4px², 4py¹, 4pz¹

Hence in Se there are two unpaired electrons hence it is paramagnetic in nature.
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zmey [24]
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n=.22/44=.005 mole of CO2
from the equation we see the relationship between the moles of co2 and O2 and we find that they have the same number of moles
So we need .005mole of O2
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3 years ago
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3 years ago
Question 15 (1 point)
Digiron [165]

Answer:

Atoms are electrically neutral because the number of protons, which carry a 1+ charge, in the nucleus of an atom is equal to the number of electrons, which carry a 1- charge, in the atom. The result is that the total positive charge of the protons cancels out the total negative charge of the electrons so that the net charge of the atom is zero. Most atoms, however, can either gain or lose electrons; when they do so, the number of electrons becomes different from the number of protons in the nucleus. The resulting charged species is called an ion.

Cations and anions

When a neutral atom loses one or more electrons, the total number of electrons decreases while the number of protons in the nucleus remains the same. The result is that the atom becomes a cation—an ion with a net positive charge.

The opposite process can also occur. When a neutral atom gains one or more electrons, the number of electrons increases while the number of protons in the nucleus remains the same. The result is that the atom becomes an anion—an ion with a net negative charge. We can illustrate this by examining some very simple cations and anions, those formed when a single hydrogen atom loses or gains an electron.

Note: Hydrogen is actually somewhat unusual in that it readily forms both cations and anions. Most elements much prefer to form only one or the other. In terms of its electron configuration, can you explain why hydrogen can form both cations and anions? Feel free to post in the comments at the end of the article!

A hydrogen cation, a hydrogen atom, and a hydrogen anion.

A hydrogen cation, a hydrogen atom, and a hydrogen anion.

Classification cation neutral atom anion

No. of protons 111 111 111

No. of electrons 000 111 222

Net charge 111++plus 000 111-−minus

If a neutral hydrogen atom ( \text{H}Hstart text, H, end text, center) loses an electron, it becomes a hydrogen cation ( \text{H}^+H  

+

start text, H, end text, start superscript, plus, end superscript, left). Conversely, if the neutral \text{H}Hstart text, H, end text atom gains an electron, it becomes a hydrogen anion ( \text{H}^-H  

−

start text, H, end text, start superscript, minus, end superscript, right), also known as a hydride ion. Image credit: adapted from Boundless Learning, CC BY-SA 4.0.

In the center column, we have a diagram of a single, neutral hydrogen atom. It contains one proton and one electron; thus, its net charge is zero. If hydrogen loses its electron, it forms the cation \text{H}^+H  

+

start text, H, end text, start superscript, plus, end superscript (left column). The \text{H}^+H  

+

start text, H, end text, start superscript, plus, end superscript cation has a net charge of 1+ from the one proton in the nucleus since there are no electrons to cancel out the positive charge. If neutral hydrogen gains an electron, it forms the anion \text{H}^-H  

−

start text, H, end text, start superscript, minus, end superscript (right column). The \text{H}^-H  

−

start text, H, end text, start superscript, minus, end superscript anion has a net charge of 1- because it has one extra electron compared to the total number of protons.

Explanation: Hopes this gives a better explanation on them!

6 0
3 years ago
The amount ofcalcium present in milk can be determined by adding oxalate to asample and measuring the massof calcium oxalate pre
Sauron [17]

<u>Answer:</u> The mass percent of calcium in milk is 0.107 %

<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 calcium oxalate = 0.429 g

Molar mass of calcium oxalate = 128.1 g/mol

Putting values in equation 1, we get:

\text{Moles of calcium oxalate}=\frac{0.429g}{128.1g/mol}=0.0033mol

The given chemical equation follows:

Na_2C_2O_4(aq.)+Ca^{2+}(aq.)\rightarrow CaC_2O_4(s)+2Na^+(aq.)

Sodium oxalate is present in excess. So, it is considered as an excess reagent. And, calcium ion is a limiting reagent because it limits the formation of product.

By Stoichiometry of the reaction:

1 mole of calcium oxalate is produced from 1 mole of calcium ion

So, 0.0033 moles of calcium oxalate is produced from = \frac{1}{1}\times 0.0033=0.0033mol of calcium ions

  • Now, calculating the mass of calcium ions by using equation 1, we get:

Moles of calcium ions = 0.0033 moles  

Molar mass of calcium ions = 40 g/mol

Putting values in equation 1, we get:

0.0033mol=\frac{\text{Mass of calcium ions}}{40g/mol}\\\\\text{Mass of calcium ions}=(0.0033mol\times 40g/mol)=0.132g

  • To calculate the mass percentage of calcium ions in milk, we use the equation:

\text{Mass percent of calcium ions}=\frac{\text{Mass of calcium ions}}{\text{Mass of milk}}\times 100

Mass of milk = 125 g

Mass of calcium ions = 0.132 g

Putting values in above equation, we get:

\text{Mass percent of calcium ions}=\frac{0.132g}{125g}\times 100=0.107\%

Hence, the mass percent of calcium in milk is 0.107 %

7 0
3 years ago
15. An electrically neutral atom consists of 15 neutrons, 13 electrons, and a number of protons. What is its mass number?​
Korvikt [17]

Answer:

28

Explanation:

it states that the atom is neutral, meaning the number of electrons and protons are the same. so if there are 13 electrons, there are 13 protons. And the mass number is neutrons plus protons. So 13+15 is 28

4 0
3 years ago
Read 2 more answers
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