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3 years ago

How do I identify significant figures in chemistry?

1 answer:

3 0

1) START counting for sig. figs. On the FIRST non-zero digit.

2) STOP counting for sig. figs. On the LAST non-zero digit.

3) Non-zero digits are ALWAYS significant.

4) Zeroes in between two non-zero digits are significant. All other zeroes are insignificant.

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2. Explain Why would it be difficult to find the volume of a rock using<br> a ruler?

dedylja [7]

Answer:

Most of these rocks are not made up of common geometric shapes

Explanation:

Because most rocks are not made up of common geometric shapes, it would be difficult or impossible to find the volume of a rock using a ruler; there would be no easy way to measure the rock's volume using a ruler

Hope this helped!

8 0

3 years ago

Use the provided reduction potentials to calculate ArGº for the following balanced redox reaction: Pb2+(aq) + Cu(s) → Pb(s) + Cu

nydimaria [60]

Answer : The correct option is, +91 kJ/mole

Solution :

The balanced cell reaction will be,

$Cu(s)+Pb^{2+}(aq)\rightarrow Cu^{2+}(aq)+Pb(s)$

Here copper (Cu) undergoes oxidation by loss of electrons, thus act as anode. Lead (Pb) undergoes reduction by gain of electrons and thus act as cathode.

First we have to calculate the standard electrode potential of the cell.

$E^0_{[Pb^{2+}/Pb]}=-0.13V$

$E^0_{[Cu^{2+}/Cu]}=+0.34V$

$E^0_{cell}=E^0_{cathode}-E^0_{anode}$

$E^0_{cell}=E^0_{[Pb^{2+}/Pb]}-E^0_{[Cu^{2+}/Cu]}$

$E^0_{cell}=-0.13V-(0.34V)=-0.47V$

Now we have to calculate the standard Gibbs free energy.

Formula used :

$\Delta G^o=-nFE^o_{cell}$

where,

$\Delta G^o$ = standard Gibbs free energy = ?

n = number of electrons = 2

F = Faraday constant = 96500 C/mole

$E^o$ = standard e.m.f of cell = -0.47 V

Now put all the given values in this formula, we get the Gibbs free energy.

$\Delta G^o=-(2\times 96500\times (-0.47))=+90710J/mole=+90.71kJ/mole\approx +91kJ/mole$

Therefore, the standard Gibbs free energy is +91 kJ/mole

6 0

3 years ago

If eggs are so fragile, how do they actually protect the growing bird?

Step2247 [10]

Although birds' eggs appear to be fragile, they are in fact extremely robust. The oval shape applies the same rules of engineering as an arched bridge; the convex surface can withstand considerable pressure without breaking.

6 0

3 years ago

Why are fibers birefringent

horrorfan [7]

Inevitable manufacturing imperfections in optical fiber leads to birefringence, which is one cause of pulse broadening in fiber-optic communications. Such imperfections can be geometrical (lack of circular symmetry), due to stress applied to the optical fiber and/or due to bending of the fiber.

4 0

3 years ago

Read 2 more answers

We have 1700 Tonnes of Amoniac every day. How many tonnes of 63% Nitrogen soda we can get?

V125BC [204]

There are 3 equations involved in manufacturing Nitric Acid from Ammonia.

First the ammonia is oxidized:
4NH3 + 5O2 = 4NO + 6H2O

Then for the absorption of the nitrogen oxides.
2NO + O2 = N2O4

Lastly, the N2O4 is further oxidized into Nitric acid.
3N2O4 + 2H2O = 4HNO3 + 2NO

Then run stoichiometry through these equations.
The first equation produces roughly 271,722,938 grams of NO
The second equation produces roughly 416,606,944 grams of N2O4
The last equation produces roughly 380,412,294 grams of HNO3 (nitric acid)

Convert the exact number back into tons, and your answer is: 419.332775 tons.

Rounded, I'm going to say that's 419.33 tons.
Hope this helps! :)

Also, it seems that commercially, Nitric Acid is commonly made by bubbling NO2 into water, rather than using ammonia.

3 0

3 years ago