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3 years ago

In which of the following is the number of electrons the ion contains given correctly?

Chemistry

2 answers:

Agata [3.3K]3 years ago

7 0

B. Cl- has 17 electrons.

katrin2010 [14]3 years ago

3 0

Answer: A) $K^+$ has 18 electrons.

Explanation: Number of electrons in an atom equals to its atomic number. A cation is formed when electrons are lost from an atom and the anion is formed when electrons are gained by an atom.

Atomic number of K(potassium) is 19. $K^+$ is formed when one electron is lost from K.

$K\rightarrow K^++1e^-$

As one electron is lost from K to form $K^+$ , the number of electrons will be 18.

The atomic number of Cl(chlorine) is 17. In choice B, we have chlorine ion, $Cl^-$ . Since it has -1 charge, the number of electrons for this ion will be 18 and not 17.

$Cl+1e^-\rightarrow Cl^-$

Atomic number of B(boron) is 5 means it has 5 electrons. In choice C, we have $B^3^+$ which is formed when 3 electrons are lost from B.

$B\rightarrow B^3^++3e^-$

As 3 electrons are lost, there will only 2 electrons remaining.

Atomic number of Ra(Radium) is 88 means it has 88 electrons. $Ra^2^+$ is formed when 2 electrons are lost from Ra.

$Ra\rightarrow Ra^2^++2e^-$

As two electrons are lost, there will be 86 electrons remaining.

So, the only correct choice is A. $K^+$ has 18 electrons.

You might be interested in

13. How many moles of sodium hydroxide are needed to neutralize 50grams of sulfuric acid?

Phoenix [80]

Answer:

1.02mole

Explanation:

The reaction equation is given as:

2NaOH + H₂SO₄ → Na₂SO₄ + 2H₂O

Given:

Mass of H₂SO₄ = 50g

Unknown:

Number of moles of NaOH = ?

Solution:

To solve this problem, we first find the number of moles of the acid given;

Number of moles = $\frac{mass}{molar mass}$

Molar mass of H₂SO₄ = 2(1) + 32 + 4(16) = 98g/mol

Now;

Number of moles = $\frac{50}{98}$ = 0.51mole

From the balanced reaction equation:

1 mole of H₂SO₄ will be neutralized by 2 mole of NaOH

0.51 mole of H₂SO₄ will be neutralized by 2 x 0.51 = 1.02mole of NaOH

6 0

3 years ago

A 3.00-kg block of copper at 23.0°C is dropped into a large vessel of liquid nitrogen at 77.3 K. How many kilograms of nitrogen

hammer [34]

Answer:

1.2584kg of nitrogen boils.

Explanation:

Consider the energy balance for the overall process. There are not heat or work fluxes to the system, so the total energy keeps the same.

For the explanation, the 1 and 2 subscripts will mean initial and final state, and C and N2 superscripts will mean copper and nitrogen respectively; also, liq and vap will mean liquid and vapor phase respectively.

The overall energy balance for the whole system is:

$U_1=U_2$

The state 1 is just composed by two phases, the solid copper and the liquid nitrogen, so: $U_1=U_1^C+U_1^{N_2}$

The state 2 is, by the other hand, composed by three phases, solid copper, liquid nitrogen and vapor nitrogen, so:

$U_2=U_2^C+U_{2,liq}^{N_2}+U_{2,vap}^{N_2}$

So, the overall energy balance is:

$U_1^C+U_1^{N_2}=U_2^C+U_{2,liq}^{N_2}+U_{2,vap}^{N_2}$

Reorganizing,

$U_1^C-U_2^C=U_{2,liq}^{N_2}+U_{2,vap}^{N_2}-U_1^{N_2}$

The left part of the equation can be written in terms of the copper Cp because for solids and liquids Cp≅Cv. The right part of the equation is written in terms of masses and specific internal energy:

$m_C*Cp*(T_1^C-T_2^C)=m_{2,liq}^{N_2}u_{2,liq}^{N_2}+m_{2,vap}^{N_2}u_{2,vap}^{N_2}-m_1^{N_2}u_1^{N_2}$

Take in mind that, for the mass balance for nitrogen, $m_1^{N_2}=m_{2,liq}^{N_2}+m_{2,vap}^{N_2}$ ,

So, let's replace $m_1^{N_2}$ in the energy balance:

$m_C*Cp*(T_1^C-T_2^C)=m_{2,liq}^{N_2}u_{2,liq}^{N_2}+m_{2,vap}^{N_2}u_{2,vap}^{N_2}-m_{2,liq}^{N_2}u_1^{N_2}-m_{2,vap}^{N_2}u_1^{N_2}$

So, as you can see, the term $m_{2,liq}^{N_2}u_{2,liq}^{N_2}$ disappear because $u_{2,liq}^{N_2}=u_{1,liq}^{N_2}$ (The specific energy in the liquid is the same because the temperature does not change).

$m_C*Cp*(T_1^C-T_2^C)=m_{2,vap}^{N_2}u_{2,vap}^{N_2}-m_{2,vap}^{N_2}u_1^{N_2}$

$m_C*Cp*(T_1^C-T_2^C)=m_{2,vap}^{N_2}(u_{2,vap}^{N_2}-u_1^{N_2})$

The difference $(u_{2,vap}^{N_2}-u_1^{N_2})$ is the latent heat of vaporization because is the specific energy difference between the vapor and the liquid phases, so:

$m_{2,vap}^{N_2}=\frac{m_C*Cp*(T_1^C-T_2^C)}{(u_{2,vap}^{N_2}-u_1^{N_2})}$

$m_{2,vap}^{N_2}=\frac{3kg*0.092\frac{cal}{gC} *(296.15K-77.3K)}{48.0\frac{cal}{g}}\\m_{2,vap}^{N_2}=1.2584kg$

3 0

4 years ago

AL2(SO4)2.XH2O has 8.1% aluminium by mass.The value of X ?

In-s [12.5K]

Answer:

jgutxutututrxxtdr

Explanation:

cjycitxutxtucj

5 0

2 years ago

Consider the following gas samples: 10. g of hydrogen gas, 10. g of helium gas, 2.5 moles of nitrogen gas, 110. g of carbon diox

Pepsi [2]

Explanation:

As we know ,

One mole of a gas contains 6.023 * 10 ²³ number of atoms .

Moles is denoted by given mass divided by the molecular mass ,

Hence ,

n = w / m

n = moles ,

w = given mass ,

m = molecular mass .

( a ) From the question ,

w = 10 g ,

As we know molecular mass of Hydrogen = 2 g/mol

Using the above formula , and putting the respective values ,

Moles = n ,

n = w / m = 10 / 2 = 5 mol

The number of atoms in one molecule of Hydrogen = 2

Hence ,

The number of atoms = 5 * 2 * 6.023 * 10 ²³ = 60.23 * 10 ²³ atoms .

( b ) From the question ,

w = 10 g

As we know molecular mass of helium gas = 4 g/mol

Using the above formula , and putting the respective values ,

Moles = n ,

n = w / m = 10 /4 = 2.5 mol

The number of atoms in one molecule of Helium = 1

Hence ,

The number of atoms = 5 * 1 * 6.023 * 10 ²³ = 30.115 * 10 ²³ atoms .

( c ) From the question ,

moles of nitrogen gas = 2.5 mol

The number of atoms in one molecule of nitrogen gas = 2

Hence ,

The number of atoms = 2.5 * 2 * 6.023 * 10 ²³ = 30.115 * 10 ²³ atoms .

( d ) From the question ,

w = 110 g

As we know molecular mass of carbon dioxide gas = 44 g/mol

Using the above formula , and putting the respective values ,

Moles = n ,

n = w / m = 110 / 44 = 2.5 mol

The number of atoms in one molecule of carbon dioxide = 3

Hence ,

The number of atoms = 2.5 * 3 * 6.023 * 10 ²³ = 45.17 * 10 ²³ atoms .

( e )

From the question ,

w = 365 g

As we know molecular mass of sulfur hexafluoride gas = 146 g/mol

Using the above formula , and putting the respective values ,

Moles = n ,

n = w / m = 365 / 146 = 2.5 mol .

The number of atoms in one molecule of sulfur hexafluoride gas = 7

Hence ,

The number of atoms = 2.5 * 7 * 6.023 * 10 ²³ = 105.40 * 10 ²³ atoms .

Hence ,

The order is -

sulfur hexafluoride > Hydrogen > carbon dioxide > nitrogen gas = helium gas

4 0

3 years ago

The distance and direction between the final position and the starting position is the?

Zielflug [23.3K]

It is the displacement.Displacement is also the most direct straight route between the starting point and the final position

4 0

3 years ago