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Alex Ar [27]
3 years ago
7

Please Help

Chemistry
1 answer:
Yuri [45]3 years ago
5 0
I believe it is A because a physical change is something that can be changed back to where a chemical change can not be such as burning something.
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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
Where are chemicals found in the home?
vodomira [7]

Answer:

c

Explanation:

chemicals can be found in every part of our lives

6 0
3 years ago
Read 2 more answers
Anybody can help? <br> - 20 points
strojnjashka [21]

Answer:

I think its carbon because of all the chemicals being used in that air.

7 0
3 years ago
Archeologists can determine the age of artifacts made of wood or bone by measuring the amount of the radioactive isotope 14C pre
Ahat [919]

Answer: The age of the tool is 15539 years

Explanation:

Expression for rate law for first order kinetics is given by:

t=\frac{2.303}{k}\log\frac{a}{a-x}

where,

k = rate constant  

t = age of sample

a = let initial amount of the reactant = 100

a - x = amount left after decay process = \frac{15.5}{100}\times 100=15.5  

a) for completion of half life:

Half life is the amount of time taken by a radioactive material to decay to half of its original value.  

t_{\frac{1}{2}}=\frac{0.693}{k}

k=\frac{0.693}{5730yr}=0.00012yr^{-1}

b) for 15.5 % of original amount

t=\frac{2.303}{0.00012}\log\frac{100}{15.5}

t=15539years

Thus age of the tool is 15539 years

8 0
3 years ago
Calculate the vapor pressure at 35ºC of a solution made by dissolving 20.2 g of sucrose (C12H22O11)in 60.5 g of water. The vapor
sukhopar [10]

Answer:

P' = 41.4 mmHg → Vapor pressure of solution

Explanation:

ΔP = P° . Xm

ΔP = Vapor pressure of pure solvent (P°) - Vapor pressure of solution (P')

Xm = Mole fraction for solute (Moles of solvent /Total moles)

Firstly we determine the mole fraction of solute.

Moles of solute → Mass . 1 mol / molar mass

20.2 g . 1 mol / 342 g = 0.0590 mol

Moles of solvent → Mass . 1mol / molar mass

60.5 g . 1 mol/ 18 g = 3.36 mol

Total moles = 3.36 mol + 0.0590 mol = 3.419 moles

Xm = 0.0590 mol / 3.419 moles → 0.0172

Let's replace the data in the formula

42.2 mmHg - P' = 42.2 mmHg . 0.0172

P' = - (42.2 mmHg . 0.0172 - 42.2 mmHg)

P' = 41.4 mmHg

5 0
3 years ago
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