Answer:
a. 0.0413 moles Zn
b. 0.0500 moles HCl
c. HCl is the limiting reactant
d. 0.0250 moles H₂
e. V = 0.56L
Explanation:
The reaction of Zn(s) with HCl is:
Zn(s) + 2HCl (aq) → ZnCl₂ (aq) + H₂(g)
<em>Where 1 mole of Zn reacts with 2 moles of HCl.</em>
a) To convert mass in grams to moles of a substance you need to use molar mass (Molar mass Zn: 65.38g/mol), thus:
2.70g Zn × (1mol / 65.38g) = <em>0.0413moles of Zn</em>
b. Now, when you have a solution in molarity (Moles / L), you can know the moles of a volume of solution, thus:
Moles HCl:
50.0mL = 0.0500L × (1.00mol / L) = <em>0.0500 moles HCl</em>
c. The limiting reactant is founded by using the chemical reaction as follows:
For a complete reaction of 0.0500 moles HCl you need:
0.0500 moles HCl × (1 mole Zn / 2 moles HCl) = 0.0250 moles Zn
<em>As you have 0.0413 moles of Zn, and you need just 0.0250 moles for the complete reaction, Zn is the exces reactant and </em><em>HCl is the limiting reactant</em>
<em />
d.As HCl is limiting reactant and 2 moles of HCl react with 1 mole of H₂, moles of hydrogen formed are:
0.0500 moles HCl × (1 mole H₂ / 2 moles HCl) = 0.0250 moles H₂
e. Using PV = nRT, you can find volume of gas, thus:
PV = nRT
V = nRT / P
<em>Where P is pressure 1atm at STP, n are moles, R is gas consant 0.08206Latm/molK and T is absolute temperature 273.15K at STP.</em>
V = 0.0250molesₓ0.082atmL/molKₓ273.15K / 1atm
V = 0.56L
of Iron.
of dihydrogen.
of Iron, hence we'll need 
of Fe2O3.