Zinc reacts with aqueous sulfuric acid to form hydrogen gas: Zn(s) + H2SO4(aq) → ZnSO4(aq) + H2(g) In an experiment, 201 mL of wet H2 is collected over water at 27 °C and a barometric pressure of 732torr. How many grams of Zn have been consumed? The vapor pressure of water at 27 °C is 26.74 torr.

Respuesta :

Answer:

0.4951 grams of Zn have been consumed.

Explanation:

Pressure at which gas is collected over water = p = 732 Torr

Vapor pressure of the water = p' = 26.74 Torr

Pressure of hydrogen gas = P

p = P + p'

P = p - p' = 732 Torr - 26.74 Torr = 705.26Torr

P = [tex]\frac{705.26}{760} atm=0.928 atm[/tex]

1 atm = 760 Torr

Volume of the hydrogen gas = V = 201 mL = 0.201 L

1 mL= 0.001 L

Moles of hydrogen gas = n

Temperature at which hydrogen gas collected = T = 27°C = 27+273 K = 300 K

Using an ideal gas equation:

[tex]PV=nRT[/tex]

[tex]n=\frac{PV}{RT}[/tex]

[tex]=\frac{0.928 atm\times 0.201 mL}{0.0821 atm L/ mol K\times 300 K}[/tex]

n = 0.007573 mol

[tex]Zn(s) + H_2SO_4(aq)\rightarrow ZnSO_4(aq) + H_2(g)[/tex]

According to recation , 1 mole of hydrgen gas was obtained from 1 mole of zinc,then 0.007573 moles of hydrgen gas will be obtained from;

[tex]\frac{1}{1}\times 0.007573 mol=0.007573 mol[/tex] of zinc

Mass of 0.007573 moles of zinc:

0.007573 mol × 65.38 g/mol = 0.4951 g

0.4951 grams of Zn have been consumed.

The mass of Zinc that has been consumed is 0.49 g

We'll begin by calculating the number of mole of H₂.

Volume (V) = 201 mL = 201 / 1000 = 0.201 L

Temperature (T) = 27 °C = 27 + 273 = 300 K

Pressure (P) = 732 – 26.74 = 705.26 torr = 705.26 / 760 = 0.928 atm

Gas constant (R) = 0.0821 atm.L/Kmol

Number of mole (n) =?

PV = nRT

Divide both side by RT

n = PV / RT

n = (0.928 × 0.201) / (0.0821 × 300)

n = 0.00757 mole

  • Next, we shall determine the mole of Zn needed to produce 0.00757 mole of H₂

Zn + H₂SO₄ —>ZnSO₄ + H₂

From the balanced equation above,

1 mole of Zn reacted to produce 1 mole of H₂.

Therefore,

0.00757 mole of Zn will also react to produce 0.00757 mole of H₂

  • Finally, we shall determine the mass of Zn that has been consumed.

Mole of Zn = 0.00757 mole

Molar mass of Zn = 65 g/mol

Mass of Zn =?

Mass = mole × molar mass

Mass of Zn = 0.00757 × 65

Mass of Zn = 0.49 g

Thus, 0.49 g of Zn has been consumed

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