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Sonja [21]
3 years ago
7

What are the reasons to determine the melting point of a sample in a melting point apparatus? Select one or more:

Chemistry
1 answer:
laila [671]3 years ago
4 0

Solution :

The reasons for the melting point determines  :

  • the assignment of the sample's purity
  • identification of the unknown sample
  • the conversion of solid sample to the liquid completely

In order to prepare the sample in the capillary tube for determining its melting point, we tap the tube gently into the sample with the open end of tube down. We then continue tapping the tube till the sample is couple of millimeters high.

Then the other close end of tube down, we tap the sample down again slowly or then dropping the tube into a longer tube so as to move down the sample faster.

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For a particular reaction, ΔH⁰ = − 46.7 kJ/mol and ΔS⁰ = − 123.8 J / (mol ⋅ K). Assuming these values change very little with te
PilotLPTM [1.2K]

Answer:

T = 377.2 K, Less than

Explanation:

The thermodynamic quantity used in predicting whether a reaction is spontaneous or not is the gibbs free energy.

It's relationship with ΔH⁰ and ΔS⁰ is given as;

ΔG° = ΔH° - TΔS°

Basically, a negative value of ΔG° means the reaction is spontaeneous.

To obtain the calculated vale of T,

ΔS° = ΔH°/T

T = ΔH° / ΔS°

T = 377.2 K

Let's calculate the value of ΔG° at that temperature.

ΔG° = ΔH° - TΔS°

ΔG° =  − 46700 - 377.2(− 123.8)

ΔG°  = 0 (approximately, values are due to the rounding off)

At ΔG°  = 0 the reaction is at equilibrium.

To find if the reaction is spontaneous at lower or hugher temperature than the calculated temperature, we would be substituting the value of T with a smaller (random) value and also a larger (random) value.

Larger T (390K)

ΔG° = ΔH° - TΔS°

ΔG° =  − 46700 - 390(− 123.8)

ΔG°  = - 46700 + 48,282

ΔG° = 1582 J/mol

Smaller T (350K)

ΔG° = ΔH° - TΔS°

ΔG° =  − 46700 - 350(− 123.8)

ΔG°  = - 46700 + 43330

ΔG° = -3370J/mol

This means the temperature would be lesser than the calculated value for it to be spontaneus.

8 0
3 years ago
Does anyone have the answers to the end of semester test B for chemistry on Edmentum?
Amanda [17]
No I do not have the answers
6 0
3 years ago
What best explains the observed trend in atomic radii going down the periodic table
Serggg [28]

going down the the periodic table, the number of shells increases resulting in an obvious increase in the atomic radii of the elements

5 0
3 years ago
Who wants to make some Chemistry????... UwU
Alik [6]

Answer:

what kind of chemistry is it going to be?

8 0
3 years ago
Read 2 more answers
Which statement explains why the noble gases are so unreactive? They have one valence electron. They have eight valence electron
SVETLANKA909090 [29]

Answer:

The answer to your question is: The second option.

Explanation:

Atoms are stable when they gain or lose electrons to have 8 electrons.

They have one valence electron.  Noble gases have 8 electrons, not one, If they would have 1 electron they would be extremely reactive.

They have eight valence electrons. This is the right answer, noble gases have 8 electrons that is why they are unreactive.

They have seven valence electrons.  If noble gases would have 7 electrons, they would be very reactive.

They have two valence electrons. This option is incorrect, elements that have 2 electrons are reactive like Calcium, Magnesium, etc.

5 0
4 years ago
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