Question

9->moles Data Table - Mg with HCI nga2 + H₂ Ptoral - Plzo =PHz Trial 1 Trial 2 Mass of magnesium Atmospheric pressure 0319 767.4 mmHg 17.5mm Hg -0429 767.4 mmHg 17.5mmites Partial pressure of water (Table 11.1) Pressure of dry hydrogen gas Volume of hydrogen gas 30-70 mL 201°C 43.05ml 20.1°C Temperature of hydrogen gas Calculate the number of moles of dry hydrogen gas for each trial from mass of Mg metal Calculate the gas constant, R, for each trial L'am Lam mol mol Basic Chemistry Laboratory Manual

Answer 1

Pressue and Temperature are same for both traails

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Mg + 2HCl + H2(g) + MgCl

1 mole of Mg liberates 1 mole of Hydrogen gas.

24 g of Mg liberates 2 g of hydrogen gas in mass terms.

0.031 g of Mg liberates how much hydrogen gas= ?

Mass of hydrogen released in Trail 1 = ( 0.031 g * 2 g ) / 24 g

= 0.00258 g

Moles of Hydrogen gas = 0.00258 g/ 2 g/mol

= 0.00129 mol of Hydrogen

value of Gas constant, R is derived by Ideal gas equation -----

pV = nRT

R = pV/nT

T = 293.25 K ( 20.1 ^oC +273.15)

pressure of dry hydrogen gas , P = 767.4 mm- 17.5 mm

= 749.9 mm

=( 749.9/760 ) atm

= 0.987atm

volume of gas = 30.70 ml

= 0.0307 L

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R = pV/nT

= 0.987 atm * 0.0307 L ) / 0.00129 mol * 293.25 K

= 0.080 Lit.atm/K.mol --------------------------------------------------------------------trail 1

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1 mole of Mg liberates 1 mole of Hydrogen gas.

24 g of Mg liberates 2 g of hydrogen gas in mass terms.

0.042 g of Mg liberates how much hydrogen gas= ?

Mass of hydrogen released in Trail 2 = ( 0.042 g * 2 g ) / 24 g

= 0.0035 g

Moles of Hydrogen gas = 0.0035 g/ 2 g/mol

= 0.00175 mol of Hydrogen

value of Gas constant, R is derived by Ideal gas equation -----

pV = nRT

R = pV/nT

T = 293.25 K ( 20.1 ^oC +273.15)

pressure of dry hydrogen gas , P = 767.4 mm- 17.5 mm

= 749.9 mm

=( 749.9/760 ) atm

= 0.987atm

volume of gas = 43.05 ml ml

= 0.04305 L

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R = pV/nT

= 0.987 atm * 0.04305 L ) / 0.00175 mol * 293.25 K

= 0.0828 Lit.atm/K.mol -------------------------------------------------------------------------trail 2