Answer:
3.066g
Explanation:
Step 1:
The balanced equation for the reaction. This is given below:
2Li + H2S —> Li2S + H2
Step 2:
Data obtained from the question.
Volume (V) of H2 = 4.5L
Temperature (T) = 315K
Pressure (P) = 1.258 atm
Note:
Gas constant (R) = 0.0821atm.L/Kmol
Number of mole (n) of H2 =..?
Step 3:
Determination of the number of mole of H2 produced.
This can be obtained by using the ideal gas equation as follow
PV = nRT
Divide both side by RT
n = PV /RT
n = 1.258 x 4.5 / 0.0821 x 315
n = 0.219 mole
Therefore, 0.219 mole of H2 is produced.
Step 4:
Determination of the number of mole of Li that will produce 0.219 mole of H2.
This is shown below:
2Li + H2S —> Li2S + H2
From the balanced equation above,
2 moles of Li reacted to produce 1 mole of H2.
Therefore, Xmol of Li will react to produce 0.219 mole of H2 i.e
Xmol of Li = 2 x 0.219
Xmol of Li = 0.438 mole
Step 5:
Conversion of 0.438 mole of Li to grams.
Number of mole of Li = 0.438 mole
Molar Mass of Li = 7g/mol
Mass = number of mole x molar Mass
Mass of Li = 0.438 x 7
Mass of Li = 3.066g
Therefore, 3.066g if Li is needed for the reaction.
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