Zn(s) + 2HCl(aq) → H2(g) + ZnCl2(aq) When 25.0 g of Zn reacts, how many L of H2 gas are formed at STP?
2 answers:
Answer : The volume of hydrogen gas formed at STP are, 8.557 liters
Explanation : Given,
Mass of zinc = 25.0 g
Molar mass of zinc = 65.38 g/mole
First we have to calculate the moles of zinc.
Now we have to calculate the moles of hydrogen gas.
The given balanced chemical reaction is,
From the balanced chemical reaction, we conclude that
As, 1 mole of Zn react to give 1 mole of hydrogen gas
So, 0.382 mole of Zn react to give 0.382 mole of hydrogen gas
Now we have to calculate the volume of hydrogen gas.
At STP,
As, 1 mole of hydrogen gas contains 22.4 L volume of hydrogen gas
So, 0.382 mole of hydrogen gas contains volume of hydrogen gas.
Therefore, the volume of hydrogen gas formed at STP are, 8.557 liters
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Answer:
Therefore = -1835 KJ
Explanation:
Enthalpy is denoted by H.
Enthalpy: Total heat change in a chemical reaction is called enthalpy.
The change of entalpy of a reaction is denoted by
Hass's Law:The change in enthalpy of any process can be determined by calculating the sum of change in enthalpy of each of the steps involved in the process.
g= gas
S= solid
P₄(g)+10Cl₂(g)→ 4Cl₅(s) =?
PCl₅(s)→ PCl₃(g)+Cl₂(g) .......(1) = +157KJ
P₄(g)+6Cl₂(g)→ 4PCl₃(g).............(2) = -1207 KJ
If we flip a reaction the value of enthalpy will be change positive to negative or nagative to positive but the numerical value will be remain same.
We need rearrange the equation (1) because in the required equation Cl₂ is on the left side. So we flip the first equation.
PCl₃(g)+Cl₂(g)→PCl₅(s)......(3) = -157KJ
Multiplying 4 with equation (3)
4 PCl₃(g)+4Cl₂(g)→4PCl₅(s)......(4) =4×( -157)KJ= -628 KJ
Adding equation (2) and (4) we get
P₄(g)+6Cl₂(g)+4 PCl₃(g)+4Cl₂(g)→4PCl₃(g)+4PCl₅(s) =( -1207-628)KJ
⇒P₄(g)+10Cl₂(g)→4PCl₃(g)-4PCl₃(g)+4PCl₅(s) = - 1835KJ
⇒P₄(g)+10Cl₂(g)→ 4Cl₅(s) = -1835 KJ
Therefore = -1835 KJ