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4 years ago

Calculate the mass percent of a NaCl solution in which 140g of NaCl is dissolved in 4.50L of water at 25C (density = 0.997g/mL).

1 answer:

6 0

Mass percent is one way of expressing concentration of a solution. It is expressed as the mass of solute per mass of solution. For this case, mass percent is calculated as follows:

% mass = 140 g NaCl / (140 g NaCl + 4500 mL ( 0.997 g/mL)) x 100
% mass = 3.03 %

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jenyasd209 [6]

Answer:

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3 years ago

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1 mole of zinc produces 1 mole of hydrogen gas.

So, 0.0851 moles of zinc will produce = $\frac{1}[1}\times 0.0851=0.0851mol$ of hydrogen gas

To calculate the volume of hydrogen gas, we use ideal gas equation, which is:

PV = nRT

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P = Pressure of hydrogen gas = Total atmospheric pressure - vapor pressure of water = (752 - 18.65) mmHg = 733.35 mmHg

V = Volume of the hydrogen gas

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R = Gas constant = $62.3637\text{ L.mmHg }mol^{-1}K^{-1}$

T = Temperature of hydrogen gas = $21^oC=[21+273]K=294K$

Putting values in above equation, we get:

$733.35mmHg\times V=0.0851mol\times 62.3637\text{ L.mmHg }mol^{-1}K^{-1}\times 294K\\\\V=\frac{0.0851\times 62.3637\times 294}{733.35}=2.13L$

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