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3 years ago

Using the words cohesive and adhesive, explain why water forms a meniscus?

1 answer:

3 0

Adhesion is responsible for a meniscus and this has to do in part with water's fairly high surface tension. Water molecules are attracted to the molecules in the wall of the glass beaker. And since water molecules like to stick together, when the molecules touching the glass cling to it, other water molecules cling to the molecules touching the glass, forming the meniscus. They'll travel up the glass as far as water's cohesive forces will allow them, until gravity prevents them from going further. Cohesion is an intermolecular attraction between like molecules (other water molecules in this case).

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15 POINTS!!!! Please answer 1-8

Effectus [21]

1. combustion
2. succession
3. condensation
4. precipitation
5. pioneer species
6. decomposition
7. evaporation
8. nitrogen fixation

4 0

3 years ago

If aluminum is diffused into a thick slice of silicon with no previous aluminum in it at a temperature of 1100˚C for 8 hours, wh

RideAnS [48]

Answer:

8.354 nanometers

Explanation:

To treat a diffusive process in function of time and distance we need to solve 2nd Ficks Law. This a partial differential equation, with certain condition the solution looks like this:

$\frac{C_{s}-C{x}}{C_{s}-C_{o}}=erf(x/2\sqrt{D*t})$

Where Cs is the concentration in the surface of the solid

Cx is the concentration at certain deep X

Co is the initial concentration of solute in the solid

and erf is the error function

Then we solve right side,

$\frac{C_{s}-C{x}}{C_{s}-C_{o}}=\frac{1018atoms/cm3-1016atoms/cm3}{1018atoms/cm3}=0.001964$

And we need to look up the inverse error function of 0.001964 resulting in: 0.00174055

Then we solve for x:

$x=0.00174055*2*\sqrt{D*t} =0.00174055*2*\sqrt{2*10^{-12}cm^{2}/s*8h*3600s/h}=8.35464*10^{-7}cm$

6 0

3 years ago

In acidic solution, the sulfate ion can be used to react with a number of metal ions. One such reaction is SO42−(aq)+Sn2+(aq)→H2

allsm [11]

Answer:

The final balanced equation is :

$SO_4^{2-}(aq)+4H^+(aq)+Sn^{2+}(aq)\rightarrow H_2SO_3(aq)+H_2O(l)+Sn^{4+}(aq)$

Explanation:

$SO_4^{2-}(aq)+Sn^{2+}(aq)\rightarrow H_2SO_3(aq)+Sn^{4+}(aq)$

Balancing in acidic medium:

First we will determine the oxidation and reduction reaction from the givne reaction :

Oxidation:

$Sn^{2+}(aq)\rightarrow Sn^{4+}(aq)$

Balance the charge by adding 2 electrons on product side:

$Sn^{2+}(aq)\rightarrow Sn^{4+}(aq)+2e^-$ ....[1]

Reduction :

$SO_4^{2-}(aq)\rightarrow H_2SO_3(aq)$

Balance O by adding water on required side:

$SO_4^{2-}(aq)\rightarrow H_2SO_3(aq)+H_2O(l)$

Now, balance H by adding $H^+$ on the required side:

$SO_4^{2-}(aq)+4H^+(aq)\rightarrow H_2SO_3(aq)+H_2O(l)$

At last balance the charge by adding electrons on the side where positive charge is more:

$SO_4^{2-}(aq)+4H^+(aq)+2e^-\rightarrow H_2SO_3(aq)+H_2O(l)$ ..[2]

Adding [1] and [2]:

$SO_4^{2-}(aq)+4H^+(aq)+Sn^{2+}(aq)\rightarrow H_2SO_3(aq)+H_2O(l)+Sn^{4+}(aq)$

The final balanced equation is :

$SO_4^{2-}(aq)+4H^+(aq)+Sn^{2+}(aq)\rightarrow H_2SO_3(aq)+H_2O(l)+Sn^{4+}(aq)$

4 0

3 years ago

When an atom is in the ground state what must happen for the atom to be in an excited state? what must happen for this atom to r

scoray [572]

Hi there

In order for an electron to jump into a higher energy state, it must first absorb energy (heat, light, etc).

When an electron goes back down to the ground state from the excited state, it emits energy usually in the form of a photon.

i hope this helps

4 0

3 years ago

Why are halogens reactive?

erica [24]

<u>Halogens are reactive because:</u>

They have high electronegativity and also high nuclear charge. So, they are reactive and also gain an electron when they react with other elements.

Since they are very reactive, halogens are very harmful to living organisms. Some of the halogens are fluorine, chlorine, bromine, iodine, astatine. These are mostly non metals. Fluorine is one of the most reactive gas and also very toxic gas. When Fluorine reacts with glass along with small amounts of water, it forms silicon tetra fluoride (SiF4). Hence fluorine should be handled with substances like the inert organofluorine compound Teflon.

8 0

3 years ago

Using the words cohesive and adhesive, explain why water forms a meniscus?​

Using the words cohesive and adhesive, explain why water forms a meniscus?