Two methanol-water mixtures are contained in separate flasks. The first mixture is 40.0 wt % methanol, and the second is 70.0 wt % methanol. If 200 g of the first mixture is combined with 150 g of the second, what will be the mass and composition of the resulting mixture?

Respuesta :

Answer: The mass of the final mixture is 350 grams and composition of methanol in the final mixture is 52.9 %

Explanation:

In first mixture:

Mass of first mixture taken, [tex]M_1[/tex] = 200 g

Percentage of methanol, [tex]\chi_m(1)[/tex] = 40 % = 0.4

Percentage of water, [tex]\chi_w(1)[/tex] = (100 - 40)% = 60% = 0.6

In second mixture:

Mass of second mixture, [tex]M_2[/tex] = 150 g

Percentage of methanol, [tex]\chi_m(2)[/tex] = 70 % = 0.7

Percentage of water, [tex]\chi_w(2)[/tex] = (100 - 70)% = 30% = 0.3

Let us consider that no chemical reaction is taking place while mixing the solutions.

Calculating the mass of methanol and water in the final mixture:

  • Mass of methanol:

[tex]m_f=[M_1\chi_m(1)+M_2\chi_m(2)][/tex]

Putting values in above equation, we get:

[tex]m_f=[(200\times 0.4)+(150\times 0.7)]=185g[/tex]

  • Mass of water:

[tex]w_f=[M_1\chi_w(1)+M_2\chi_w(2)][/tex]

Putting values in above equation, we get:

[tex]w_f=[(200\times 0.6)+(150\times 0.3)]=165g[/tex]

Total mass of the final mixture = [tex]m_f+w_f=185+165=350g[/tex]

To calculate the percentage composition of methanol in final mixture, we use the equation:

[tex]\%\text{ composition of methanol}=\frac{\text{Mass of methanol}}{\text{Mass of final mixture}}\times 100[/tex]

Mass of final mixture = 350 g

Mass of methanol = 185 g

Putting values in above equation, we get:

[tex]\%\text{ composition of methanol in final mixture}=\frac{185g}{350g}\times 100=52.9\%[/tex]

Hence, the mass of the final mixture is 350 grams and composition of methanol in the final mixture is 52.9 %

Each of the methanol–water mixture contribute the amount by weight of

methanol given in their composition.

  • The mass and composition of the resulting mixture is 350 g, and approximately 52.9 wt% methanol.

Reasons:

The given parameters are;

Number of methanol–water mixtures = 2

Weight percentage of methanol in the first mixture = 40.0 wt %

Weight percentage in the second mixture = 70.0 wt %

Mass of the first mixture in the resulting mixture = 200 g

Mass of the second mixture in the resulting mixture = 150 g

Therefore;

  • Mass of the resulting mixture = 200 g + 150 g = 350 g

[tex]\displaystyle Methanol \ contribution \ from \ the \ first \ mixture = \frac{40}{100} \times 200 \, g= \mathbf{80 \, g}[/tex]

[tex]\displaystyle Methanol \ contribution \ from \ the \ second \ mixture = \frac{70}{100} \times 150\, g= \mathbf{105 \, g}[/tex]

Mass of methanol in the resulting mixture, M = 80 g + 105 g = 185 g

[tex]\displaystyle Percentage \ by \ weight \ of \ methanol \ in \ resulting \ mixture = \frac{185}{350} \times 100 \approx 52.9 \%[/tex]

  • The composition of the resulting mixture is approximately 52.9 wt % methanol

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