Excess HCl (aq) was added to a 0.500g sample of magnesium metal and sodium chlor

Question

Excess HCl (aq) was added to a 0.500g sample of magnesium metal and sodium chloride. The hydrogen from the reaction with magnesium was collected. From the following information, determine the% of magnesium in the sample. v(H2)=0.129 L T=22. Celsius P atm=755 torr P (H20)=19.8 mm hg Excess HCl (aq) was added to a 0.500g sample of magnesium metal and sodium chloride. The hydrogen from the reaction with magnesium was collected. From the following information, determine the% of magnesium in the sample. v(H2)=0.129 L T=22. Celsius P atm=755 torr P (H20)=19.8 mm hg T=22. Celsius P atm=755 torr P (H20)=19.8 mm hg

Explanation / Answer

                           Mg(s) + 2HCl(aq) ---> MgCl2(aq) + H2(g)

According to reaction 1mole Mg relesed to 1 mole of H2 gas , so we have to calculate how many moles H2 gas released during the reaction

PV= nRT

Here ,P= 755 torr =0.99343 atm, T= 295K, and V=0.129L n= moles of H2 released.

Therefore n = PV/RT= (0.99343 atm *0.129L )/ (0.0821L atm K-1 mole-1*295K)= 5.2912*10^-3 moles

So number of moles of Mg present in the solution= 5.2912*10^-3 moles

Therefore weight of Mg = 5.2912*10^-3 * 24.305 =0.1286 gms

% of Magnesium weight =( 0.1286/0.5) *100= 25.72%

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