Answer:
a) 2.94 g of zinc
b) volume of gas = 0.379 L
Step-by-step explanation:
Part 1:
Data Given:
volume of gas (H₂) = 1 L
mass of Zn = ?
Reaction Given:
Zn+2HCI -------> ZnCI₂ + H₂
Solution:
To find mass of zinc first find number of mole of 1 L gas (H₂)
formula used
no. of mole = volume of gas/ molar volume at STP
As we Know
molar volume at STP = 22.414 mol/L
Put value in above formula
no. of mole = 1 L / 22.414 (mol/L)
no. of mole = 0.045 mol
So
1 L of gas (H₂) = 0.045 mol
Now Look at the reaction
Zn + 2 HCI -------> ZnCI₂ + H₂
1 mol 1 mol
As 1 mole of zinc form 1 mole of H₂ then how many moles will require to form 0.045 mole of gas (H₂).
Apply unity formula
1 mole of zinc ≅ 1 mole of H₂
X moles of zinc ≅ 0.045 mole of H₂
Do cross multiplication
moles of zinc = 1 mole x 0.045 mole / 1 mole
moles of zinc = 0.045 mole
To find mass of Zinc, convert no moles to mass
Formula Used
mass in grams = no. of moles x molar mass . . . . . . . .(1)
molar mass of zinc = 65.4 g/mol
Put values in equation 1
mass in grams = 0.045 mole x 65.4 g/mol
mass in grams = 2.94 g
So,
2.94 g of zinc is required to form 1 L of the gas at STP
____________
Part 2.
Data given:
Temperature (T) = 22 °C
Pressure (P) = 0.976 atm
convert °C to kelvin
T = °C + 273
T = 22 °C + 273
T = 295 K
volume of gas = ?
Mass of zinc = 1 g
Solution:
To find volume formula used
PV= nRT
Rearrange the equation for Volume
V = nRT / P . . . . . . . . . (1)
where
P = pressure
V = Volume
T= Temperature
n = Number of moles
R = ideal gas constant = 0.08206 L.atm / mol. K
For this we have to know the mole of the znic
The formula will be used
no. of moles = mass in grams / molar mass . . . . . . (2)
Molar mass of Zn = 65.4 g/mol
Put values in equation 2
no. of moles = 1 g / 65.4 g/mol
no. of moles = 0.0153 mol
Now put the value in formula (2) to calculate volume of gas
V = 0.0153 mol x 295 K x 0.08206 (L.atm/mol. K) / 0.976 atm
V = 0.3699 (L.atm) /0.976 atm
V = 0.379 L
So,
The volume of gas will be 0.379 L