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3 years ago

What is the entropy change for freezing 2.71 g of C2H5OH at 158.7 K? ∆H = −4600 J/mol. Answer in units of J/K.

Chemistry

1 answer:

Ira Lisetskai [31]3 years ago

4 0

Answer:

-1.71 J/K

Explanation:

To solve this problem we use the formula

ΔS = n*ΔH/T

Where n is mol, ΔH is enthalpy and T is temperature.

ΔH and T are already given by the problem, so now we calculate n:

Molar Mass C₂H₅OH = 46 g/mol

2.71 g C₂H₅OH ÷ 46g/mol = 0.0589 mol

Now we calculate ΔS:

ΔS = 0.0589 mol * −4600 J/mol / 158.7 K

ΔS = -1.71 J/K

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Convert from moles to particles 6.02x1023 particles 1 mole Question 2. 2.7 moles of lithium Question 3. 1.8 moles of sodium chlo

spayn [35]

Considering the definition of Avogadro's number:

the number of molecules of lithium is 1.62621×10²⁴ molecules.
the number of molecules of sodium chloride is 1.08414×10²⁴ molecules.

<h3>Definition of Avogadro's number</h3>

Avogadro's Number or Avogadro's Constant is called the number of particles that make up a substance (usually atoms or molecules) and that can be found in the amount of one mole of said substance. Its value is 6.023×10²³ particles per mole. Avogadro's number applies to any substance.

<h3>Amount of molecules in this case</h3>

You can apply the following rule of three, considering the Avogadro's number: If 1 mole of lithium contains 6.023×10²³ molecules, 2.7 moles of lithium contains how many molecules?

amount of molecules of lithium= (6.023×10²³ molecules × 2.7 moles)÷1 mole

<u><em>amount of molecules of lithium=1.62621×10²⁴ molecules</em></u>

Finally, the number of molecules of lithium is 1.62621×10²⁴ molecules.

On the other hand you can apply the following rule of three, considering the Avogadro's number: If 1 mole of sodium chloride contains 6.023×10²³ molecules, 1.8 moles of sodium chloride contains how many molecules?

amount of molecules of sodium chloride= (6.023×10²³ molecules × 1.8 moles)÷1 mole

<u><em>amount of molecules of sodium chloride=1.08414 ×10²⁴ molecules</em></u>

Finally, the number of molecules of sodium chloride is 1.08414×10²⁴ molecules.

Learn more about Avogadro's Number:

brainly.com/question/11907018

brainly.com/question/1445383

brainly.com/question/1528951

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4 0

2 years ago

What is the molarity of a solution that is composed of 10 grams of Sodium Chloride ( NaCl) dissolved in 3.50 L of water

Gennadij [26K]

<u>Answer:</u> The molarity of solution will be 0.049 M

<u>Explanation:</u>

Molarity is defined as the amount of solute expressed in the number of moles present per liter of solution. The units of molarity are mol/L. The formula used to calculate molarity:

$\text{Molarity of solution}=\frac{\text{Given mass of solute}}{\text{Molar mass of solute}\times \text{Volume of solution (L)}}$

We are given:

Given mass of sodium chloride = 10 g

Molar mass of sodium chloride = 58.44 g/mol

Volume of solution = 3.50 L

Putting values in above equation:

$\text{Molarity of NaCl}=\frac{10 g}{58.44g/mol\times 3.50}\\\\\text{Molarity of NaCl}=0.049M$

Hence, the molarity of solution will be 0.049 M

6 0

3 years ago

1. For one atom of lithium -6 I will need_____ atom of lithium -7 for an average atomic mass of 6.944? 2. For one atom of lithiu

Hoochie [10]

Answer:

For one atom of lithium -6 I will need_16.85____ atom of lithium -7 for an average atomic mass of 6.944 .

Explanation:

1 ) Let required atom be m .

$\frac{6\times 1 + 7\times m}{1 + m} = 6.944$

6 + 7m = 6.944 + 6.944m

7 m - 6.944 m = .944

.056 m = .944

m = 16.85

6 0

4 years ago

Some signs of chemical change include

choli [55]

Answer:

I think it would be A honestly...

5 0

3 years ago

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What carries the useful energy of a lamp to its surroundings?

serious [3.7K]

A. The potential energy from the batteries in the torch is transferred to the filament of the bulb. The energy is transferred to the surroundings as thermal energy and light. Most of the energy is transferred as thermal energy which is not useful and only some of the energy is transferred as light

6 0

3 years ago