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kiruha [24]
3 years ago
15

Why is the spot of drink placed above the water line at the start of the process

Chemistry
2 answers:
Elena L [17]3 years ago
4 0
This is the answer. Hope this helps!

Klio2033 [76]3 years ago
3 0

Answer: The solvent gives extra energy to pull up the sample and the sample will also dissolve in the solvent. That's why as precautionary measure start line should stay above the solvent in chromatography.The baseline must be above the solvent level in the TLC chamber, so the solvent does not dilute to samples so much that they dissolve.

Explanation:

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Which conclusion is supported by the information in the graph?
Molodets [167]

Answer:

A. The cost of producing a kilowatt of power with fuel cell will be less than $30 in 2015

4 0
2 years ago
A small piece of hot metal is placed in cooler water. The metal is left in the water
scoundrel [369]

Answer: The amount of energy lost by the metal is equal to the amount of energy gained by the water

Explanation:

5 0
2 years ago
The ideal gas heat capacity of nitrogen varies with temperature. It is given by:
hammer [34]

Answer:

A)  1059 J/mol

B)  17,920 J/mol

Explanation:

Given that:

Cp = 29.42 - (2.170*10^-3 ) T + (0.0582*10^-5 ) T2 + (1.305*10^-8 ) T3 – (0.823*10^-11) T4

R (constant) = 8.314

We know that:

C_p=C_v+R

We can determine C_v from above if we make C_v the subject of the formula as:

C_v=C_p-R

C_V = 29.42-(2.7*10^{-3})T+(5.82*10^{-7})T2-(1.305*10^{-8})T3-(8.23*10^{-12})T4-8.314

C_V = 21.106-(2.7*10^{-3})T+(5.82*10^{-7})T2-(1.305*10^{-8})T3-(8.23*10^{-12})T4

A).

The formula for calculating change in internal energy is given as:

dU=C_vdT

If we integrate above data into the equation; it implies that:

U2-U1=\int\limits^{500}_{450}(21.106-(2.7*10^{-3})T+(5.82*10^{-7})T2-(1.305*10^{-8})T3-(8.23*10^{-12})T4\,) du

U2-U1=\int\limits^{500}_{450}(21.106-(2.7*10^{-3})T/1+(5.82*10^{-7})T2/2-(1.305*10^{-8})T3/3-(8.23*10^{-12})T4/4\,)

U2-U1= 1059J/mol

Hence, the internal energy that must be added to nitrogen in order to increase its temperature from 450 to 500 K = 1059 J/mol.

B).

If we repeat part A for an initial temperature of 273 K and final temperature of 1073 K.

then T = 273 K & T2 = 1073 K

∴

U2-U1=\int\limits^{500}_{450}(21.106-(2.7*10^{-3})T/1+(5.82*10^{-7})T2/2-(1.305*10^{-8})T3/3-(8.23*10^{-12})T4/4\,)

U2-U1=\int\limits^{500}_{450}(21.106-(2.7*10^{-3})273/1+(5.82*10^{-7})1073/2-(1.305*10^{-8})T3/3-(8.23*10^{-12})T4/4\,)

U2-U1= 17,920 J/mol

3 0
4 years ago
Root nodules are associations between bacteria and plant roots responsible for
max2010maxim [7]

Answer: Root nodules are associations between bacteria and plant roots responsible for nitrogen fixation.

Explanation:

  • As nitrogen present in atmosphere cannot be used by plants directly.
  • Nitrogen present in atmosphere is converted into nitrogen compounds by bacteria which is present in root nodules of a plant.
  • These compounds of nitrogen are then used by plants for various functions.
8 0
3 years ago
A sample of helium gas inside a closed but flexible container occupies a volume of 355mL at 23°C. If the pressure is held consta
guapka [62]

Answer:

978.19° C

Explanation:

P1V1/T1 =P2V2/T2     Since the pressure is constant, this can be written as

V1/T1 = V2/T2      RE-ARRANGE TO

V2 *  T1/V1   = T2       Note:  T must be in Kelvin!!

1.5 L  *  (273.15 + 23)  / (.355 L ) = T2 = 1251.338 K  =978.19 C

6 0
2 years ago
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