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2 years ago

How much heat is required to heat 9.61g of ethanol (CH3CH2OH) from 24.10C to 67.30C?

Chemistry

1 answer:

Licemer1 [7]2 years ago

8 0

Answer:

a.)

To warm the liquid from 35°C to 78°C:

(2.3 J/g-K) x (42.0 g) x (78 - 35) = 4154 J

To vaporize the liquid at 78°C:

(38.56 kJ/mol) x (42.0 g C2H5OH / 46.06867 g C2H5OH/mol) = 35.154 kJ

Total:

4.154 kJ + 35.154 kJ = 39.3 kJ

b.)

To warm the solid from -155°C to -114°C:

(0.97 J/g-K) x (42.0 g) x (-114°C - (-155°C)) = 1670 J

To melt the solid at -114°C:

(5.02 kJ/mol) x (42.0 g C2H5OH / 46.06867 g C2H5OH/mol) = 4.5766 kJ

To warm the liquid from -114°C to 78°C:

(2.3 J/g-K) x (42.0 g) x (78 - (-114)) = 18547 J

To vaporize the liquid at 78°C:

35.154 kJ (as in part a.)

Total:

1.670 kJ + 4.5766 kJ + 18.547 kJ + 35.154 kJ = 59.9 kJ

Explanation:

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When diluting the pickle juice food sample for titration, is it important to know the final volume exactly? Why or why not?

maks197457 [2]

Explanation:

When diluting a fruit juice, it is important to know the final volume so as not to over dilute the solution.

The fruit juice can become too diluted if we don't know the final volume .
Concentration refers to the amount of solute dissolved in a solvent.
To achieve a desired amount of concentration during dilution, the volume of the target must be known.
This will serve as a guide of the amount of solvent to add in order to take the solution to the desired volume.

Learn more:

Dilution brainly.com/question/11493179

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1 year ago

If 0.640 g of beautiful blue crystals of azulene is dissolve in 99 g of benzen, the resulting solutions boils at 80.23 degrees c

devlian [24]

This problem handles boiling-point elevation, which means we will use the formula:

ΔT = Kb * m

Where ΔT is the difference of Temperature between boiling points of the solution and the pure solvent (Tsolution - Tsolvent). Kb is the ebullioscopic constant of the solvent (2.64 for benzene), and m is the molality of the solution.

Knowing that benzene's boiling point is 80.1°C, we solve for m:

Tsolution - Tsolvent = Kb * m

80.23 - 80.1 = 2.64 * m

m = 0.049 m

We use the definition of molality to calculate the moles of azulene:

0.049 m = Xmoles azulene / 0.099 kgBenzene

Xmoles azulene = 4.87 x10⁻³ moles azulene

We use the mass and the moles of azulene to calculate its molecular weight:

0.640 g / 4.875 x10⁻³ mol = 130.28 g/mol

A molecular formula that would fulfill that molecular weight is C₁₀H₁₀. So that's the result of solving this problem.

The actual molecular formula of azulene is C₁₀H₈.

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2 years ago

In the Acid-Base Chemistry Experiment the measurement of pH will be used to explore acid-base concepts, analyze an unknown, and

aleksley [76]

Answer

a) A solution with a hydronium molarity of 0.00045 is acidic. True

Doing the calculus of pH

$pH= -Log [H^{+}] = -Log (0.00045)$

b) pH is a way to express the hydronium concentration over a wide range. True

pH means –Log[H+] and this value is used to express a wide range of hydronium concentration sometimes obtaining pH minor than zero.

c) Percent K and Fe are determined by doing ion exchange then a pH titration. False

Usually, Fe is determined by redox titration with potassium permanganate due to it’s more accurate. On the other hand, K is determined usually by volumetric process which includes precipitation like potassium picrate precipitate

d) About 0.2M HCl is the reagent used for the pH titrations. False.

In order to do pH titration, it is possible to use a wide range of HCl concentrations and other acids as reagent if the analyte is a basic compound. Otherwise, if the analyte is an acid compound you should use a basic compound as reagent.

e) A Lewis base is specie that can donate a proton to an acid. False

A Lewis base is an electron pair donor.

5 0

2 years ago

The pKs of succinic acid are 4.21 and 5.64. How many grams of monosodium succinate (FW = 140 g/mol) and disodium succinate (FW =

Varvara68 [4.7K]

Answer:

9.744g of monosodium succinate.

4.925g of disodium succinate.

Explanation:

To find pH of the buffer produced by the mixture of monosodium succinate-Disodium succinate is obtained from H-H equation:

pH = pKa + log ([Na₂Suc] / [NaHSuc])

As you want a pH of 5.28 and pKa is 5.64:

5.28 = 5.64 + log ([Na₂Suc] / [NaHSuc])

-0.36 = log ([Na₂Suc] / [NaHSuc])

0.4365 = ([Na₂Suc] / [NaHSuc]) (1)

As total concentration of the buffer is 100mM = 0.100M:

0.100M = [Na₂Suc] + [NaHSuc] (2)

Replacing (2) in (1):

0.4365 = (0.100M - [NaHSuc] / [NaHSuc])

0.4365 [NaHSuc] = 0.100M - [NaHSuc]

1.4365 [NaHSuc] = 0.100M

[NaHSuc] = 0.0696M

And:

[Na₂Suc] = 0.0304M

As volume of the buffer is 1L:

[NaHSuc] = 0.0696 moles

[Na₂Suc] = 0.0304 moles

Using molar mass of both substances:

Mass of monosodium succinate:

0.0696moles * (140g / 1mol) = 9.744g of monosodium succinate.

Mass of disodium succinate:

0.0304moles * (162g / 1mol) = 4.925g of disodium succinate.

5 0

2 years ago

Which atomic model states that it is impossible to know the exact location of electrons around the nucleus?

dedylja [7]

Answer:

the Bohr model, an electron's position is known precisely because it orbits the nucleus in a fixed path. In the electron cloud model, the electron's position cannot be known precisely. Only its probable location can be known.

8 0

1 year ago

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