Chemistry: Brass is a substitutional alloy consisting of a solution of copper and zinc. a particular sample of red brass consisting of 79.0% cu and 21.0% zn by mass has a density of 8740 kg/m3.what is the molality and molarity of zn in the solid solution?

Brass is a substitutional alloy consisting of a

Ответ:

zay179

02.01.2022

The molality and molarity of zinc in the solution is 4.07 m and 28.11 M respectively.

Explanation:

Solute is the substance which is present in smaller proportion in a mixture and solvent is the substance which is present in larger proportion in a mixture.

We are given:

(m/m) % of Cu = 79 %

This means that 79 g of copper is present in 100 grams of alloy.

(m/m) % of Zn = 21 %

This means that 21 g of zinc is present in 100 grams of alloy.

As, zinc is present in smaller proportion. So, it is solute and copper is the solvent.

Calculating molality of zinc:

To calculate molality of the zinc, we use the equation:

$Molality=\frac{m_{solute}\times 1000}{M_{solute}\times W_{solvent}\text{ in grams}}$

where,

$m_{solute}$ = Given mass of solute (Zinc ) = 21 g

$M_{solute}$ = Molar mass of solute (Zinc) = 65.3 g/mol

$W_{solvent}$ = Mass of solvent (copper) = 79 g

Putting values in above equation, we get:

$\text{Molality of Zinc}=\frac{21\times 1000}{65.3\times 79}\\\\\text{Molality of zinc}=4.07m$

Calculating molarity of zinc:

To calculate volume of a substance, we use the equation:

$\text{Density of substance}=\frac{\text{Mass of substance}}{\text{Volume of substance}}$

Density of solution = $8740kg/m^3=\frac{8740kg\frac{1000g}{1kg}}{1m^3\times \frac{10^6cm^3}{1m^3}}=\frac{8740g}{1000cm^3}=8.740g/cm^3$

(Conversion factors used are: 1 kg = 1000 g & 1m^3=10^6cm^3 )

Mass of solution = 100 g

Putting values in above equation, we get:

$8.740g/cm^3=\frac{100.0g}{\text{Volume of zinc}}\\\\\text{Volume of zinc}=11.44cm^3$

To calculate the molarity of solution, we use the equation:

$\text{Molarity of the solution}=\frac{\text{Mass of solute}\times 1000}{\text{Molar mass of solute}\times \text{Volume of solution (in mL)}}$

We are given:

Molar mass of zinc = 65.3 g/mol

Volume of solution = 11.44cm^3=11.44mL (Conversion factor: 1cm^3=1mL )

Mass of zinc = 21.0 g

Putting values in above equation, we get:

$\text{Molarity of zinc}=\frac{21\times 1000}{65.3\times 11.44}=28.11M$

Hence, the molality and molarity of zinc in the solution is 4.07 m and 28.11 M respectively.

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Ответ:

NotYourStudent

18.10.2021

Chemistry

1. Plasma is "the state..." because plasma is rarely natural on earth (only lightning strikes) and has the highest temp

gas is "particles move freely" they do move freely

liquid is "it expands to fill volume" they do not have definite boundaries so they fill up the container

solid is "it retains its shape" yup dis is pretty obvious ig

I agree with your answers.

it wouldnt be hypothesis or theory because they are basically the same thing and they explain facts. fact would be the best answer

conduct experiments would be the most logical here because you can gain new knowledge from conducting experiments instead of the rest.

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Brass is a substitutional alloy consisting of a solution of copper and zinc. a particular sample of red brass consisting of 79.0% cu and 21.0% zn by mass has a density of 8740 kg/m3.what is the molality and molarity of zn in the solid solution?

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