Most atoms are stable when they have _____ electrons in their outer shell

When a substance undergoes a chemical change, the product exhibits different physical properties than the starting material. Des

elena55 [62]

Answer:

I) Change in solubility

II) Change in boiling point

III) Change in colour

Explanation:

A chemical change involves formation of new products and is not reversible.

So, once two liquid solutions are mixed and a chemical change takes place, the new product will have the following:

- a new solubility rate, i.e it will dissolve at a rate different from the two liquid solution

- a new boiling point i.e it takes a new point at which its molecules liberate to yield vapour

- a new colour might be detected, as the individual solution each has its own colour

6 0

3 years ago

The following reaction plays a key role in the destruction of ozone In the atmosphere:

lys-0071 [83]

Answer:

19.91 J/K

Explanation:

The entropy is a measure of the randomness of the system, and it intends to increase in nature, thus for a spontaneous reaction ΔS > 0.

The entropy variation can be found by:

ΔS = ∑n*S° products - ∑n*S° reactants

Where n is the coefficient of the substance. The value of S° (standard molar entropy) can be found at a thermodynamic table.

S°, Cl(g) = 165.20 J/mol.K

S°, O3(g) = 238.93 J/mol.K

S°, O2(g) = 205.138 J/mol.K

So:

ΔS = (1*205.138 + 1*218.9) - (1*165.20 + 1*238.93)

ΔS = 19.91 J/K

6 0

3 years ago

An atorn has 9 electrons and 9 protons at the start. If it loses 2 electrons, the net charge on the atom will be. If the atom in

LUCKY_DIMON [66]

Answer:

If it loses 2 electrons, the net charge on the atom will be 2+

If the atom instead gains 4 electrons, the net charge will be 4-

Explanation:

It is based on adding and subtracting charges. Protons are +1 and electrons are -1

If the atom has 9 protons and 9 electrons, the net charge is +9 + (-9) = 0. The +9 is the 9 protons and the -9 is from the 9 electrons.

If two electrons are taken away, there would be 9-2 or 7 electrons with 9 protons. The net charge would then be +9 + (-7) = +2. +9 comes from the 9 electrons and -7 is from the 7 electrons.

So, if two electrons are taken away, the net charge is +2.

Similarly, if the atom gains 4 electrons, there will be 9+4 or 12 electrons and 9 protons. The net charge would then be +9 + (-12) = -4. +9 comes from the 9 protons and -12 comes from the 12 electrons.

So, if 4 electrons are added, the net charge is -4.

3 0

3 years ago

Osmosis is the process responsible for carrying nutrients and water from groundwater supplies to the upper parts of trees. The o

liberstina [14]

Answer: Molar concentration of the tree sap have to be 0.783 M

Explanation:

To calculate the concentration of solute, we use the equation for osmotic pressure, which is:

$\pi=iCRT$

where,

$\pi$ = osmotic pressure of the solution = 19.6 atm

i = Van't hoff factor = 1 (for non-electrolytes)

R = Gas constant = $0.0821\text{ L.atm }mol^{-1}K^{-1}$

T = temperature of the solution = $32^oC=[273+32]=305K$

Putting values in above equation, we get:

$19.6atm=1\times C\times 0.0821\text{ L.atm }mol^{-1}K^{-1}\times 305K$

$C=0.783M$

Thus the molar concentration of the tree sap have to be 0.783 M to achieve this pressure on a day when the temperature is 32°C

4 0

3 years ago

Contrast the silica content of magma in quiet and explosive eruptions

klemol [59]

Magma in quiet eruptions has a low content in silica , while in explosive eruptions, it has a high Content in silica. A volcano that erupts quietly has magma that is low in silica. Low-silica magma has low viscosity and flows easily. A volcano that erupts explosively has magma that is high in silica. High-silica magma has high viscosity, making it thick and sticky, thus it flows slowly.

3 0

3 years ago