Aluminum reacts with excess hydrochloric acid to form aqueous aluminum chloride and 190.6 ml of hydrogen gas (collected over water at 26°C and 0.89 atm). (Vapor pressure of water at 26ºC = 25.2 mmHg.) How many grams of aluminum reacted? Enter to 4 decimal places.

Respuesta :

Answer:0.119g

Explanation:equation of rxn is

2Al+6HCl=2AlCl3+3H2

From ideal gas eqn

PV=nRT

n=PV/RT

P here is the partial pressure of H2 from the qtn.According to Dalton law of partial pressure, PT=PH2+PH20

PT=0.89atm given

PH20=25.2mmhg given=25.2/760atm,=0.033atm

PH2=PT-PH20

PH2=0.89-0.033=0.857atm

T=26+273=299K

R=0.082atmdm^-3mol^-1K^-1

V=190.6ml=190.6cm3=190.6/1000=0.1906dm3

n=PV/RT

n=0.857*0.1906/0.082*299

=0.00667moles of H2.

From the eqn of reaction,

2moles of Al reacts to gv 3moles of H2

xmoles of Al will give 0.00667moles of H2

xmoles=0.00667*2/3 (cross multiplying)=0.00444moles of Al

From the relationship, n=mass/MW

mass=MW*n

MW of Al=27g/mol

mass=0.0044moles*27g/moles

mass=0.119grams of Al.

The mass of aluminum that has reacted is 0.119 g.  The mass of the reactant can be calculated by finding its moles.

How to calculate the mass of the reactant?

the mass of the reactant can be calculated by finding its moles in the reaction and putting the value in the mole formula.

The given reaction is:

[tex]\bold {2Al+6HCl\rightarrow 2AlCl_3+3H_2}[/tex]

First, calculate the moles of the Hydrogen from the ideal gas equation,

[tex]n=\dfrac {0.857\times 0.1906}{0.082\times 299}\\\\ n = \rm 0.00667 \ moles \ of \ H2.[/tex]

The molar ratio between Al and [tex]\bold {H_2 }[/tex] is 3:2.

Thus, moles of Aluminium is:

[tex]\text{Moles of Al} = 0.00667\times \dfrac 23 \\\\\text{Moles of Al} = 0.00444 \rm \ moles[/tex]

Thus the mass of Aluminium,

[tex]m ={\rm 0.0044 \ moles\times 27 \ g/moles}\\\\m = 0.119\rm \ g[/tex]

Therefore, the mass of aluminum that has reacted is 0.119 g.

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