Which compound is produced by a neutralization?

How many valence electrons does a helium atom have? what is the formula of the ion formed when potassium achieves noble-gas elec

OlgaM077 [116]

> How many valence electrons does a helium atom have?

The electron configuration of Helium is simply 1s2. We see that its outermost shell is the s shell and it contains 2 electrons, therefore the number of valence electrons is also 2.

> What is the formula of the ion formed when potassium achieves noble-gas electron configuration?

Potassium has a electron configuration of [Ar] 4s1. To have an electron configuration of only [Ar] which is a noble gas, the one electron from 4s1 should be removed, hence:

K+

3 0

3 years ago

A hot-water stream at 70°C enters an adiabatic mixing chamber with a mass flow rate of 3.6 kg/s, where it is mixed with a stream

cupoosta [38]

Answer:

a) 4.58 kg/s

b) 0.105 kW/K

Explanation:

a) For the energy balance

qin = qout

min*cin*Tin = mout*cout*Tout

Where min is the mass flow that is entering the system, cin is the specific heat of the substance that is entering, Tin is the temperature of the substance that is entering, and the out is from the substances that are leaving the system. Because there is only water in the system cin = cout. The energy balance will be then:

mh*Th + mc*Tc = (mh + mc)*Tmix

Where h is from the hot water, c is from the cold water, and mix for the mixture that leaves the chamber. Th = 70ºC + 273 = 343 K, Tc = 20ºC + 273 = 293 K, Tmix = 42ºC + 273 = 315 K

3.6*343 + mc*293 = (3.6 + mc)*315

293mc - 315mc = 3.6*315 - 3.6*343

- mc*(315 - 293) = -3.6*(343 - 315)

mc = 3.6*(343 - 315)/(315 - 293)

mc = 3.6*28/22

mc = 4.58 kg/s

b) The entropy balance is:

Sin + Sout - Sgen = ΔSsystem

Where Sin is the entropy of the entering substances, Sout the entropy that the leaving substances, and Sgen the entropy that is generated in the process.

The entropy variantion for an adiabatic process is 0, so ΔSsystem = 0

Sgen = Sin + Sout

The sum of entropy is:

m*cp*ln(Tfinal/Tinitial), where cp is the specific heat (4.184 kJ/kg.K)

Sgen = mc*cp*ln(Tmix/Tc) + mh*cp*ln(Tmix/th)

Sgen = 4.58*4.184*ln(315/293) + 3.6*4.184*ln(315/343)

Sgen = 1.3874 + (-1.2827)

Sgen = 0.105 kW/K

5 0

2 years ago

What is the mass number of an ion with 107 electrons, 159 neutrons, and a +1 charge? express your answer as an integer?

Darya [45]

The mass number of an ion is calculated by adding the neutrons and electrons together. In this case 159+107=266. However, since this ion has a +1 charge, you must add 1 to the electrons. This would give a total mass of 267.

6 0

2 years ago

1 What characteristic of an element determines how its atoms can bond with other atoms?

Masja [62]

Answer:

Electrons

Explanation:

The electrons of the outermost energy level determine the energetic stability of the atom and its tendency to form chemical bonds with other atoms to form molecules. Under standard conditions, atoms fill the inner shells first, often resulting in a variable number of electrons in the outermost shell.

8 0

3 years ago

If 500.0 mL of 0.10 M Ca2+ is mixed with 500.0 mL of 0.10 M SO42−, what mass of calcium sulfate will precipitate? Ksp for CaSO4

statuscvo [17]

Answer:

The mass of calcium sulfate that will precipitate is 6.14 grams

Explanation:

Step 1: Data given

500.0 mL of 0.10 M Ca^2+ is mixed with 500.0 mL of 0.10 M SO4^2−

Ksp for CaSO4 is 2.40*10^−5

Step 2: Calculate moles of Ca^2+

Moles of Ca^2+ = Molarity Ca^2+ * volume

Moles of Ca^2+ = 0.10 * 0.500 L

Moles Ca^2+ = 0.05 moles

Step 3: Calculate moles of SO4^2-

Moles of SO4^2- = 0.10 * 0.500 L

Moles SO4^2- = 0.05 moles

Step 4: Calculate total volume

500.0 mL + 500.0 mL = 1000 mL = 1L

Step 5: Calculate Q

Q = [Ca2+] [SO42-]

[Ca2+]= 0.050 M [O42-]

Qsp = (0.050)(0.050 )=0.0025 >> Ksp

This means precipitation will occur

Step 6: Calculate molar solubility

Ksp = 2.40 * 10^-5 = [Ca2+][SO42-] =(x)(x)

2.40 * 10^-5 = x²

x = √(2.40 * 10^-5)

x = 0.0049 M = Molar solubility

Step 7: Calculate total CaSO4 dissolved

total CaSO4 dissolved = 0.0049 M * 1 L * 136.14 mol/L = 0.667 g

Step 8: Calculate initial mass of CaSO4

Since initial moles CaSo4 = 0.050

Initial mass of CaSO4 = 0.050 * 136.14 g/mol

Initial mass of CaSO4 = 6.807 grams

Step 9: Calculate mass precipitate

6.807 - 0.667 = 6.14 grams

The mass of calcium sulfate that will precipitate is 6.14 grams

5 0

3 years ago