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asambeis [7]
3 years ago
11

2.00 g of an unknown volatile liquid was placed in a flask with a total volume of 265.0 mL. The cover of the flask has only a pi

nhole, which allows the internal pressure to equilibrate with the outside pressure. The temperature was raised to 100.00C by placing the flask in a constant temperature water bath. At this temperature, it was found that only 0.581 g of the liquid substance remained in the flask. A barometer in the lab showed the pressure to be 752 mm Hg. What's the molar mass of the unknown liquid?
Chemistry
1 answer:
Zarrin [17]3 years ago
4 0

Answer:

165.52 g/mol

Explanation:

Upon temperature was raised to 100 C part of the initial mass of liquid is gas, exactly: 2.00-0.581 = 1.419 g.  This gas occupy a volume of approximately 265 mL, its pressure of 752 mm Hg and its temperature is 100 C. Assuming that this gas behaves as gas ideal we can estimate the molecular weight M_Wtaking into account tha gas ideal law:

PVM_{W}=RTm  with R= 0.082 atm L/(mol K)

or M_{W}=\frac{RTm}{PV}

Before using of the formula, we need convert volume units to L (1L=1000 mL) pressure to atm (1 atm=760 mmHg) and temperature to K (K=273+C).

265/1000 = 0.265 L

752/760=0.989 atm

273+100=373 K

Finally, replacing in the formula

\frac{0.082*1.419*373}{0.989*0.265}=165.52 g/mol

 

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Grace [21]
The most common reaction that causes spoilage isn't a reaction at all. Molds and Bacteria are attracted to the easily found presence of water in the fruit. They find a natural place to reproduce and what they do causes spoilage.

Very few sources talk about the chemical changes that take place. If you put fruit in a refrigerator it slows the spoiling process down. That means that the chemical reaction has to be endothermic (it requires heat to occur)

The process of spoilage is speeded up by bananas for example, giving up Ethylene gas. You do not want to put a banana with tomatoes, because tomatoes are very sensitive to Ethylene. (It's OK to eat them together. They make a terrific salad. Yum).

I cannot find a definitive source that connects all this together, but the conduct of the fruit in refrigerators confirms what I am saying.

Spoilage is a very complex reaction and interaction with the environment. I have given you a hint of what happens but you should search it out to convince yourself of the outcome.
3 0
3 years ago
How many moles of oxygen are needed to react with 87 grams of aluminum
labwork [276]

Answer:

2.4 moles of oxygen are needed to react with 87 g of aluminium.

Explanation:

Chemical equation:

4Al(s)  + 3O₂(l)   → 2AlO₃(s)

Given data:

Mass of aluminium = 87 g

Moles of oxygen needed = ?

Solution:

Moles of aluminium:

Number of moles of aluminium= Mass/ molar mass

Number of moles of aluminium= 87 g/ 27 g/mol

Number of moles of aluminium= 3.2 mol

Now we will compare the moles of aluminium with oxygen.

                              Al         :         O₂

                               4          :         3

                               3.2       :         3/4×3.2 = 2.4 mol

2.4 moles of oxygen are needed to react with 87 g of aluminium.

5 0
3 years ago
What amount (moles) is represented by each of these samples?
Zinaida [17]
<h3>Answer:</h3>

                  a)  Moles of Caffeine  =  1.0 × 10⁻⁴ mol

                  b) Moles of Ethanol   =  4.5 × 10⁻³ mol

<h3>Solution:</h3>

Data Given:

                  Mass of Caffeine  =  20 mg  =  0.02 g

                  M.Mass of Caffeine  =  194.19 g.mol⁻¹

                  Molecules of Ethanol  =  2.72 × 10²¹

Calculate Moles of Caffeine as,

                               Moles  =  Mass ÷ M.Mass

Putting values,

                               Moles  =  0.02 g ÷ 194.19 g.mol⁻¹

                                Moles  =  1.0 × 10⁻⁴ mol

Calculate Moles of Ethanol as,

                                                         As we know one mole of any substance contains 6.022 × 10²³ particles (atoms, ions, molecules or formula units). This number is also called as Avogadro's Number.

The relation between Moles, Number of Particles and Avogadro's Number is given as,

                          Number of Moles  =  Number of Molecules ÷ 6.022 × 10²³

Putting values,

                          Number of Moles  =  2.72 × 10²¹ Molecules ÷ 6.022 × 10²³

                          Number of Moles  =  4.5 × 10⁻³ Moles

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joja [24]

Answer: The correct answer is a) Acetylcholine.

Explanation:

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Therefore the correct answer is a) Acetylcholine.

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