Which is the last thing to be seen before a total eclipse?

1 answer:

8 0

When the Moon has nearly blocked out the sun at the last few minutes before the total solar eclipse, you will see some points of light surrounding the edges of the dark Moon. These look like a string of beads wrapped around the edges and are appropriately called Baily's Beads. They are named after the astronomer Francis Baily who first noticed them in the 18th century. These beads only appear for a few brief minutes before the total solar eclipse occurs.

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The enthalpy change for converting 1.00 mol of ice at -50.0 ∘c to water at 60.0∘c is ________ kj. the specific heats of ice, wat

guajiro [1.7K]

First, we have to get:

1- The heat required to increase T of ice from -50 to 0 °C:

according to q formula:

q1 = m*C*ΔT

when m is the mass of ice = mol * molar mass

= 1 mol * 18 mol/g

= 18 g

and C is the specific heat capacity of ice = 2.09 J/g-K

and ΔT change in temperature = 0- (-50) = 50°C

by substitution:

∴q1 = 18 g * 2.09 J/g-K *50°C

= 1881 J = 1.881 KJ

2- the heat required to melt this mass of ice is :

q2 = n*ΔHfus

when n is the number of moles of ice = 1 mol

and ΔHfus = 6.01 KJ/mol

by substitution:

q2 = 1 mol * 6.01 KJ/mol

= 6.01 KJ

3- the heat required to increase the water temperature from 0°C to 60 °C is:

q3 = m*C*ΔT

when m is the mass of water = 18 g

C is the specific heat capacity of water = 4.18 J/g-K

ΔT is the change of Temperature of water = 60°C - 0°C = 60°C

by substitution:

∴q3 = 18 g * 4.18 J/g-K * 60°C

= 4514 J = 4.514 KJ

∴the total change of enthalpy = q1+q2+q3

= 1.881 KJ +6.01 KJ + 4.514 KJ

= 12.405 KJ

5 0

3 years ago

A standard 10.00 g mass is weighed on an analytical balance 100 times. The average and standard deviation obtained gives 10.12 ±

Mekhanik [1.2K]

Answer:

There was an improvement in accuracy. There was no change in precision.

Explanation:

The average mass after recalibration is closer to the mass of the standard, so the recalibration improved the accuracy (the measurement is closer to an accepted 'true' value).

The standard deviation did not change, so the precision (or how disperse the measurements are) was not affected.

5 0

3 years ago

What is the ph of a solution with h+ = 7.0* 10

Mekhanik [1.2K]

Do you mean h=7.0+10? If so your answer is 70.

8 0

3 years ago

Of these non-metals which one is likely to be least reactive

natulia [17]

Answer:

the answer is the swecond option

Explanation:

Its b ur well come

7 0

3 years ago

Name the salt used in plastering the fractured bone

Eddi Din [679]

Answer: Calcium Sulphate Hemihydrate

The compound of calcium which is used for plastering of fractured bones is Plaster of Paris. It is also called as Calcium Sulphate Hemihydrate.

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3 years ago