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timurjin [86]
3 years ago
8

The enthalpy of fusion of solid n-butane is 4.66 kJ/mol. Calculate the energy required to melt 58.3 g of solid n-butane.

Chemistry
1 answer:
adelina 88 [10]3 years ago
7 0

Answer : The energy required to melt 58.3 g of solid n-butane is, 4.66 kJ

Explanation :

First we have to calculate the moles of n-butane.

\text{Moles of n-butane}=\frac{\text{Mass of n-butane}}{\text{Molar mass of n-butane}}

Given:

Molar mass of n-butane = 58.12 g/mole

Mass of n-butane = 58.3 g

Now put all the given values in the above expression, we get:

\text{Moles of n-butane}=\frac{58.3g}{58.12g/mol}=1.00mol

Now we have to calculate the energy required.

Q=\frac{\Delta H}{n}

where,

Q = energy required

\Delta H = enthalpy of fusion of solid n-butane = 4.66 kJ/mol

n = moles = 1.00 mol

Now put all the given values in the above expression, we get:

Q=\frac{4.66kJ/mol}{1.00mol}=4.66kJ

Thus, the energy required to melt 58.3 g of solid n-butane is, 4.66 kJ

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Answer:

1. 6.005 g

2. 22.9 mL

3. Until the mixtures becomes homogeneous.

Explanation:

A buffer is a solution where a weak acid is in equilibrium with its conjugate base (its anion) or a weak base is in equilibrium with its conjugate base (its cation). The buffer remains the pH almost unaltered because it shifts the equilibrium if an acid or base is added.

1. The pH of a buffer can be calculated by the Henderson-Hasselbalch equation:

pH = pKa + log[A⁻]/[HA]

Where [A⁻] is the concentration of the conjugate base (the anion) of the acid, and HA is the acid concentration.

5.10 = 4.76 + log[A⁻]/[HA]

log[A⁻]/[HA] = 5.10 - 4.76

log[A⁻]/[HA] = 0.34

[A⁻]/[HA] = 10^{0.34}

[A⁻]/[HA] = 2.1878

Because the volume is the same, we can replace the concentration by the number of moles (n):

nA⁻/nHA = 2.1878

nA⁻ = 2.1878*nHA

The total number of moles of the substances in the buffer is: 0.200 mol/L * 0.5 L = 0.1 mol

nA⁻ + nHA = 0.1

2.1878*nHA + n HA = 0.1

3.1878nHA = 0.1

nHA = 0.0314 mol

nA⁻ = 0.0686 mol

The total number of moles of acetic acid needed is 0.1 mol (both substances may be from it):

m = MW*mol

m = 60.05*0.1 = 6.005 g

2. NaOH must react with acetic acid to form the anion, so for a 1:1 reaction, it will be needed 0.0686 mol of NaOH:

V = mol/concentration

V = 0.0686/3

V = 0.0229 L = 22.9 mL

3. The buffer must be a homogeneous solution, it means that it can't be noticed phases in the buffer, so the flask must be inverted until all the buffer is diluted in water, and it will be noticed when the solution becomes homogenous.

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Answer:

37.5 g NaCl

Explanation:

Step 1: Given data

  • Concentration of NaCl: 15.0% m/m
  • Mass of the solution: 250.0 g

Step 2: Calculate how many grams of NaCl are in 250.0 g of solution

The concentration of NaCl is 15.0% by mass, that is, there are 15.0 g of NaCl every 100 g of solution.

250.0 g Solution × 15.0 g NaCl/100 g Solution = 37.5 g NaCl

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Answer:

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Explanation:

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2 HCl + Ba(OH)₂ ⇒ BaCl₂ + 2 H₂O

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                            3(46) kg--------------   2(63) kg  

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Answer:

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