Sunspots appear dark because they are what ?

1 answer:

dsp732 years ago

3 0

Sunspots have strong magnetic fields, thus being much cooler than their surroundings. Yet, they are still individually very hot and can reach up to a temp of 3,800 K. But since they are cooler than their surroundings, they appear to be much darker to the visible eye.

Let me know if you need anything further. :)

- Dotz

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What is the molality of a solution containing 10.0 G of NA2 S04 and 1000.0 G of water

galina1969 [7]

Explanation:

1 literThe total of water is equal to 1000.0 g of water

we need to find the molality of a solution containing 10.0 g of dissolved in Na₂S0₄1000.0 g of water

1. For that find the molar mass

Na: 2 x 22.99= 45.98

S: 32.07

O: 4 x 16= 64

The total molar mass is 142.05

We have to find the number of moles, y

To find the number of moles divide 10.0g by 142.05 g/mol.

So the number of moles is 0.0704 moles.

For the molarity, you need the number of moles divided by the volume. So, 0.0704 mol/1 L.

The molarity would end up being 0.0704 M

The molality of a solution containing 10.0 g of Na2SO4 dissolved in 1000.0 g of water is 0.0704 Mliter

7 0

2 years ago

Based on the sign of E cell, classify these reactions as spontaneous or non spontaneous as written.? assume standard conditions.

sammy [17]

A electrochemical reaction is said to be spontaneous, if $E^{0} cell is positive.$

Answer 1:
Consider reaction: Ni^2+ (aq) + S^2- (aq) ----> + Ni (s) + S (s)

The cell representation of above reaction is given by;
 $S^{2-}/S // Ni^{2+}/Ni$

Hence, $E^{0}cell = E^{0} Ni^{2+/Ni} - E^{0} S/S^{2-}$
we know that, ${E^{0} Ni^{2+}/Ni = -0.25 v$
and ${E^{0} S/ S^{2-} = -0.47 v$

Therefore, $E^{0} cell$ = - 0.25 - (-0.47) = 0.22 v

Since, $E^{0} cell$ is positive, hence cell reaction is spontaneous
.....................................................................................................................

Answer 2:
Consider reaction: Pb^2+ (aq) +H2 (g) ----> Pb (s) +2H^+ (aq)

The cell representation of above reaction is given by;
 $H_{2} / H^{+} // Pb^{2+} /Pb$

Hence, $E^{0}cell = E^{0} Pb/Pb^{2+} - E^{0} H_{2}/H^{+}$
we know that, ${E^{0} Pb^{2+}/Pb = -0.126 v$
and ${E^{0} H_{2}/ H^{+} = -0 v$

Therefore, $E^{0} cell$ = - 0.126 - 0 = -0.126 v

Since, $E^{0} cell$ is negative, hence cell reaction is non-spontaneous.

....................................................................................................................

Answer 3:
Consider reaction: 2Ag^+ (aq) + Cr(s) ---> 2 Ag (s) +Cr^2+ (aq)

The cell representation of above reaction is given by;
 $Cr/Cr^{2+} // Ag^{+}/Ag$

Hence, $E^{0}cell = E^{0} Ag^{+}/Ag - E^{0} Cr/Cr^{2+}$
we know that, ${E^{0} Ag^{+}/Ag = -0.22 v$
and ${E^{0} Cr/ Cr^{2+} = -0.913 v$

Therefore, $E^{0} cell$ = - 0.22 - (-0.913) = 0.693 v

Since, $E^{0} cell$ is positive, hence cell reaction is spontaneous

8 0

3 years ago

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A molecule involves two atoms in a chemical bond that do what share?

Viefleur [7K]

B. Share Electrons.
Hope this helps.

4 0

3 years ago

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A 93-L sample of dry air is cooled from 145 oC to -22 oC at a constant pressure of 2.85 atmospheres). What is the final volume?

Aloiza [94]

Answer: 55.84L