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Vika [28.1K]
3 years ago
7

What are the signs that you are getting nervous 18 POINTS )

Chemistry
1 answer:
AlexFokin [52]3 years ago
8 0
- hands start getting sweaty
- nail biting or perhaps shaking legs
- the feeling of being overwhelmed
- (for some people) the stomach starts to hurt
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How do you find the atomic weight of an atom?
wariber [46]

Answer: The atomic weight of any atom can be found by multiplying the abundance of an isotope of an element by the atomic mass of the element and then adding the results together. This equation can be used with elements with two or more isotopes: Carbon-12: 0.9889 x 12.0000 = 11.8668. Carbon-13: 0.0111 x 13.0034 = 0.1443.

Explanation:

6 0
3 years ago
A runner wants to run 13.1 km . She knows that her running pace is 6.2 mi/h .How many minutes must she run? Hint: Use 6.2 mi/h a
frutty [35]

Answer:

  • <u>79 minutes</u>

Explanation:

1)<u> Convert the distance, 13.1 km to miles</u>

  • Conversion factor:

        1 = 1 mi / 1.61 km

  • 13.1 km [ 1 mi /  1.61 km ] = 8.1336 mi

2)<u> Use 6.2 mi/h as a converstion factor between distance and time</u>

  • 8.1366 mi × 1 / [6.2 mi/h] = 1.3124 h

3) <u>Convert 1.3124 h to minutes</u>

  • 1.3124 h × [ 60 min/h] = 78.7 min

Rounding to the nearest minutes (two significant figures):

  • 79 min ← answer
4 0
3 years ago
Be sure to answer all parts. Styrene is produced by catalytic dehydrogenation of ethylbenzene at high temperature in the presenc
svlad2 [7]

Answer:

a) ΔHºrxn = 116.3 kJ, ΔGºrxn = 82.8 kJ,  ΔSºrxn =  0.113 kJ/K

b) At 753.55 ºC or higher

c )ΔG =  1.8 x 10⁴ J

    K = 8.2 x 10⁻²

Explanation:

a)                                 C6H5−CH2CH3  ⇒  C6H5−CH=CH2  + H₂

ΔHf kJ/mol                    -12.5                           103.8                      0

ΔGºf kJ/K                        119.7                         202.5                      0

Sº J/mol                          255                          238                      130.6*

Note: This value was not given in our question, but is necessary and can be found in standard handbooks.

Using Hess law to calculate  ΔHºrxn we have

ΔHºrxn  = ΔHfº C6H5−CH=CH2 +  ΔHfº H₂ - ΔHºfC6H5−CH2CH3

ΔHºrxn =     103.8 kJ + 0 kJ  - (-12.5 kJ)

ΔHºrxn = 116.3 kJ

Similarly,

ΔGrxn = ΔGºf C6H5−CH=CH2 +  ΔGºfH₂ - ΔGºfC6H5CH2CH3

ΔGºrxn=   202.5 kJ + 0 kJ - 119.7 kJ  = 82.8 kJ

ΔSºrxn = 238 J/mol + 130.6 J/mol -255 J/K = 113.6 J/K = 0.113 kJ/K

b) The temperature at which the reaction is spontaneous or feasible occurs when ΔG becomes negative and using

ΔGrxn =  ΔHrxn -TΔS

we see that will happen when the term  TΔS  becomes greater than ΔHrxn since ΔS  is positive  , and so to sollve for T we will make ΔGrxn equal to zero and solve for T. Notice here we will make the assumption that  ΔºHrxn and ΔSºrxn remain constant at the higher temperature  and will equal the values previously calculated for them. Although this assumption is not entirely correct, it can be used.

0 = 116 kJ -T (0.113 kJ/K)

T = 1026.5 K  =  (1026.55 - 273 ) ºC = 753.55 ºC

c) Again we will use

                       ΔGrxn =  ΔHrxn -TΔS

to calculate ΔGrxn   with the assumption that ΔHº and ΔSºremain constant.

ΔG =  116.3 kJ - (600+273 K) x 0.113 kJ/K =  116.3 kJ - 873 K x 0.113 kJ/K

ΔG =  116.3 kJ - 98.6 kJ =  17.65 kJ = 1.8 x 10⁴ J ( Note the kJ are converted to J to necessary for the next part of the problem )

Now for solving for K, the equation to use is

ΔG = -RTlnK and solve for K

- ΔG / RT = lnK  ∴ K = exp (- ΔG / RT)

K = exp ( - 1.8 x 10⁴ J /( 8.314 J/K  x 873 K)) = 8.2 x 10⁻²

8 0
3 years ago
All molecular motion stops at 0 on this scale
Oxana [17]
Kelvin Hope this helps
4 0
3 years ago
Read 2 more answers
PLEASE PLEASE HELP ME
Norma-Jean [14]

The high surface tension helps the paper clip - with much higher density - float on the water. The property of the surface of a liquid that allows it to resist an external force, due to the cohesive nature of its molecules.

Basically it means that there is a sort of skin on the surface of water where the water molecules hold on tight together. If the conditions are right, they can hold tight enough to support your paper clip. The paperclip is not truly floating, it is being held up by the surface tension.

5 0
3 years ago
Read 2 more answers
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